updater: refactoring and set DNS server correctly

- Fix CLI operation not setting DNS server
- Fix periodic operation not setting DNS server
- Set DNS address for resolution once at start for both CLI and periodic operation
- Inject resolver to each provider instead of creating it within
- Use resolver settings on every call to `.Resolve` method, instead of passing it to constructor
- Move out minServers check from resolver

cmd/gluetun/main.go

@@ -39,6 +39,7 @@ import (
 	"github.com/qdm12/gluetun/internal/storage"
 	"github.com/qdm12/gluetun/internal/tun"
 	updater "github.com/qdm12/gluetun/internal/updater/loop"
+	"github.com/qdm12/gluetun/internal/updater/resolver"
 	"github.com/qdm12/gluetun/internal/updater/unzip"
 	"github.com/qdm12/gluetun/internal/vpn"
 	"github.com/qdm12/golibs/command"
@@ -379,7 +380,9 @@ func _main(ctx context.Context, buildInfo models.BuildInformation,
 	updaterLogger := logger.New(log.SetComponent("updater"))
 
 	unzipper := unzip.New(httpClient)
-	providers := provider.NewProviders(storage, time.Now, updaterLogger, httpClient, unzipper)
+	parallelResolver := resolver.NewParallelResolver(allSettings.Updater.DNSAddress.String())
+	providers := provider.NewProviders(storage, time.Now,
+		updaterLogger, httpClient, unzipper, parallelResolver)
 
 	vpnLogger := logger.New(log.SetComponent("vpn"))
 	vpnLooper := vpn.NewLoop(allSettings.VPN, allSettings.Firewall.VPNInputPorts,

internal/cli/openvpnconfig.go

@@ -3,6 +3,7 @@ package cli
 import (
 	"context"
 	"fmt"
+	"net"
 	"net/http"
 	"strings"
 	"time"
@@ -11,6 +12,7 @@ import (
 	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/provider"
 	"github.com/qdm12/gluetun/internal/storage"
+	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
 type OpenvpnConfigLogger interface {
@@ -23,6 +25,11 @@ type Unzipper interface {
 		contents map[string][]byte, err error)
 }
 
+type ParallelResolver interface {
+	Resolve(ctx context.Context, settings resolver.ParallelSettings) (
+		hostToIPs map[string][]net.IP, warnings []string, err error)
+}
+
 func (c *CLI) OpenvpnConfig(logger OpenvpnConfigLogger, source sources.Source) error {
 	storage, err := storage.New(logger, constants.ServersData)
 	if err != nil {
@@ -42,8 +49,9 @@ func (c *CLI) OpenvpnConfig(logger OpenvpnConfigLogger, source sources.Source) e
 	unzipper := (Unzipper)(nil)
 	client := (*http.Client)(nil)
 	warner := (Warner)(nil)
+	parallelResolver := (ParallelResolver)(nil)
 
-	providers := provider.NewProviders(storage, time.Now, warner, client, unzipper)
+	providers := provider.NewProviders(storage, time.Now, warner, client, unzipper, parallelResolver)
 	providerConf := providers.Get(*allSettings.VPN.Provider.Name)
 	connection, err := providerConf.GetConnection(allSettings.VPN.Provider.ServerSelection)
 	if err != nil {

internal/cli/update.go

@@ -16,6 +16,7 @@ import (
 	"github.com/qdm12/gluetun/internal/provider"
 	"github.com/qdm12/gluetun/internal/storage"
 	"github.com/qdm12/gluetun/internal/updater"
+	"github.com/qdm12/gluetun/internal/updater/resolver"
 	"github.com/qdm12/gluetun/internal/updater/unzip"
 )
 
@@ -71,17 +72,17 @@ func (c *CLI) Update(ctx context.Context, args []string, logger UpdaterLogger) e
 		return fmt.Errorf("options validation failed: %w", err)
 	}
 
-	const clientTimeout = 10 * time.Second
-	httpClient := &http.Client{Timeout: clientTimeout}
-
 	storage, err := storage.New(logger, constants.ServersData)
 	if err != nil {
 		return fmt.Errorf("cannot create servers storage: %w", err)
 	}
 
+	const clientTimeout = 10 * time.Second
+	httpClient := &http.Client{Timeout: clientTimeout}
 	unzipper := unzip.New(httpClient)
+	parallelResolver := resolver.NewParallelResolver(options.DNSAddress.String())
 
-	providers := provider.NewProviders(storage, time.Now, logger, httpClient, unzipper)
+	providers := provider.NewProviders(storage, time.Now, logger, httpClient, unzipper, parallelResolver)
 
 	updater := updater.New(httpClient, storage, providers, logger)
 	err = updater.UpdateServers(ctx, options.Providers)

internal/provider/common/mocks.go

@@ -12,6 +12,7 @@ import (
 	gomock "github.com/golang/mock/gomock"
 	settings "github.com/qdm12/gluetun/internal/configuration/settings"
 	models "github.com/qdm12/gluetun/internal/models"
+	resolver "github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
 // MockParallelResolver is a mock of ParallelResolver interface.
@@ -38,9 +39,9 @@ func (m *MockParallelResolver) EXPECT() *MockParallelResolverMockRecorder {
 }
 
 // Resolve mocks base method.
-func (m *MockParallelResolver) Resolve(arg0 context.Context, arg1 []string, arg2 int) (map[string][]net.IP, []string, error) {
+func (m *MockParallelResolver) Resolve(arg0 context.Context, arg1 resolver.ParallelSettings) (map[string][]net.IP, []string, error) {
 	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "Resolve", arg0, arg1, arg2)
+	ret := m.ctrl.Call(m, "Resolve", arg0, arg1)
 	ret0, _ := ret[0].(map[string][]net.IP)
 	ret1, _ := ret[1].([]string)
 	ret2, _ := ret[2].(error)
@@ -48,9 +49,9 @@ func (m *MockParallelResolver) Resolve(arg0 context.Context, arg1 []string, arg2
 }
 
 // Resolve indicates an expected call of Resolve.
-func (mr *MockParallelResolverMockRecorder) Resolve(arg0, arg1, arg2 interface{}) *gomock.Call {
+func (mr *MockParallelResolverMockRecorder) Resolve(arg0, arg1 interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Resolve", reflect.TypeOf((*MockParallelResolver)(nil).Resolve), arg0, arg1, arg2)
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Resolve", reflect.TypeOf((*MockParallelResolver)(nil).Resolve), arg0, arg1)
 }
 
 // MockStorage is a mock of Storage interface.

internal/provider/common/updater.go

@@ -6,6 +6,7 @@ import (
 	"net"
 
 	"github.com/qdm12/gluetun/internal/models"
+	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
 var ErrNotEnoughServers = errors.New("not enough servers found")
@@ -15,7 +16,7 @@ type Fetcher interface {
 }
 
 type ParallelResolver interface {
-	Resolve(ctx context.Context, hosts []string, minToFind int) (
+	Resolve(ctx context.Context, settings resolver.ParallelSettings) (
 		hostToIPs map[string][]net.IP, warnings []string, err error)
 }
 

internal/provider/cyberghost/provider.go

@@ -16,12 +16,13 @@ type Provider struct {
 	common.Fetcher
 }
 
-func New(storage common.Storage, randSource rand.Source) *Provider {
+func New(storage common.Storage, randSource rand.Source,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Cyberghost),
-		Fetcher:         updater.New(),
+		Fetcher:         updater.New(parallelResolver),
 	}
 }
 

internal/provider/cyberghost/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 1
 		maxDuration     = 20 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 4
 		maxFails        = 10
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/cyberghost/updater/servers.go

@@ -4,9 +4,11 @@ package updater
 
 import (
 	"context"
+	"fmt"
 	"sort"
 
 	"github.com/qdm12/gluetun/internal/models"
+	"github.com/qdm12/gluetun/internal/provider/common"
 )
 
 func (u *Updater) FetchServers(ctx context.Context, minServers int) (
@@ -14,11 +16,17 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	possibleServers := getPossibleServers()
 
 	possibleHosts := possibleServers.hostsSlice()
-	hostToIPs, _, err := u.presolver.Resolve(ctx, possibleHosts, minServers)
+	resolveSettings := parallelResolverSettings(possibleHosts)
+	hostToIPs, _, err := u.presolver.Resolve(ctx, resolveSettings)
 	if err != nil {
 		return nil, err
 	}
 
+	if len(hostToIPs) < minServers {
+		return nil, fmt.Errorf("%w: %d and expected at least %d",
+			common.ErrNotEnoughServers, len(servers), minServers)
+	}
+
 	possibleServers.adaptWithIPs(hostToIPs)
 
 	servers = possibleServers.toSlice()

internal/provider/cyberghost/updater/updater.go

@@ -8,8 +8,8 @@ type Updater struct {
 	presolver common.ParallelResolver
 }
 
-func New() *Updater {
+func New(parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 	}
 }

internal/provider/expressvpn/connection_test.go

@@ -89,7 +89,8 @@ func Test_Provider_GetConnection(t *testing.T) {
 
 			unzipper := (common.Unzipper)(nil)
 			warner := (common.Warner)(nil)
-			provider := New(storage, randSource, unzipper, warner)
+			parallelResolver := (common.ParallelResolver)(nil)
+			provider := New(storage, randSource, unzipper, warner, parallelResolver)
 
 			if testCase.panicMessage != "" {
 				assert.PanicsWithValue(t, testCase.panicMessage, func() {

internal/provider/expressvpn/provider.go

@@ -17,12 +17,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	unzipper common.Unzipper, updaterWarner common.Warner) *Provider {
+	unzipper common.Unzipper, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Expressvpn),
-		Fetcher:         updater.New(unzipper, updaterWarner),
+		Fetcher:         updater.New(unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/expressvpn/updater/resolve.go

@@ -6,13 +6,14 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() *resolver.Parallel {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio = 0.1
 		maxNoNew     = 1
 		maxFails     = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration: time.Second,
@@ -21,5 +22,4 @@ func newParallelResolver() *resolver.Parallel {
 			SortIPs:     true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/expressvpn/updater/servers.go

@@ -21,7 +21,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		hosts[i] = servers[i].Hostname
 	}
 
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}

internal/provider/expressvpn/updater/updater.go

@@ -10,10 +10,11 @@ type Updater struct {
 	warner    common.Warner
 }
 
-func New(unzipper common.Unzipper, warner common.Warner) *Updater {
+func New(unzipper common.Unzipper, warner common.Warner,
+	parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		unzipper:  unzipper,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/fastestvpn/provider.go

@@ -17,12 +17,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	unzipper common.Unzipper, updaterWarner common.Warner) *Provider {
+	unzipper common.Unzipper, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Fastestvpn),
-		Fetcher:         updater.New(unzipper, updaterWarner),
+		Fetcher:         updater.New(unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/fastestvpn/updater/resolve.go

@@ -6,13 +6,14 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() *resolver.Parallel {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio = 0.1
 		maxNoNew     = 1
 		maxFails     = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration: time.Second,
@@ -21,5 +22,4 @@ func newParallelResolver() *resolver.Parallel {
 			SortIPs:     true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/fastestvpn/updater/servers.go

@@ -56,7 +56,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	}
 
 	hosts := hts.toHostsSlice()
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -64,15 +65,15 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
-	hts.adaptWithIPs(hostToIPs)
-
-	servers = hts.toServersSlice()
-
-	if len(servers) < minServers {
+	if len(hostToIPs) < minServers {
 		return nil, fmt.Errorf("%w: %d and expected at least %d",
 			common.ErrNotEnoughServers, len(servers), minServers)
 	}
 
+	hts.adaptWithIPs(hostToIPs)
+
+	servers = hts.toServersSlice()
+
 	sort.Sort(models.SortableServers(servers))
 
 	return servers, nil

internal/provider/fastestvpn/updater/updater.go

@@ -10,10 +10,11 @@ type Updater struct {
 	warner    common.Warner
 }
 
-func New(unzipper common.Unzipper, warner common.Warner) *Updater {
+func New(unzipper common.Unzipper, warner common.Warner,
+	parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		unzipper:  unzipper,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/hidemyass/provider.go

@@ -18,12 +18,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	client *http.Client, updaterWarner common.Warner) *Provider {
+	client *http.Client, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.HideMyAss),
-		Fetcher:         updater.New(client, updaterWarner),
+		Fetcher:         updater.New(client, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/hidemyass/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() *resolver.Parallel {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 15 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() *resolver.Parallel {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() *resolver.Parallel {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/hidemyass/updater/servers.go

@@ -26,7 +26,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 			common.ErrNotEnoughServers, len(hosts), minServers)
 	}
 
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -34,6 +35,11 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
+	if len(hostToIPs) < minServers {
+		return nil, fmt.Errorf("%w: %d and expected at least %d",
+			common.ErrNotEnoughServers, len(servers), minServers)
+	}
+
 	servers = make([]models.Server, 0, len(hostToIPs))
 	for host, IPs := range hostToIPs {
 		tcpURL, tcp := tcpHostToURL[host]

internal/provider/hidemyass/updater/updater.go

@@ -12,10 +12,11 @@ type Updater struct {
 	warner    common.Warner
 }
 
-func New(client *http.Client, warner common.Warner) *Updater {
+func New(client *http.Client, warner common.Warner,
+	parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		client:    client,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/ipvanish/provider.go

@@ -17,12 +17,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	unzipper common.Unzipper, updaterWarner common.Warner) *Provider {
+	unzipper common.Unzipper, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Ipvanish),
-		Fetcher:         updater.New(unzipper, updaterWarner),
+		Fetcher:         updater.New(unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/ipvanish/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 20 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/ipvanish/updater/servers.go

@@ -67,7 +67,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	}
 
 	hosts := hts.toHostsSlice()
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -75,15 +76,15 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
-	hts.adaptWithIPs(hostToIPs)
-
-	servers = hts.toServersSlice()
-
-	if len(servers) < minServers {
+	if len(hostToIPs) < minServers {
 		return nil, fmt.Errorf("%w: %d and expected at least %d",
 			common.ErrNotEnoughServers, len(servers), minServers)
 	}
 
+	hts.adaptWithIPs(hostToIPs)
+
+	servers = hts.toServersSlice()
+
 	sort.Sort(models.SortableServers(servers))
 
 	return servers, nil

internal/provider/ipvanish/updater/servers_test.go

@@ -5,11 +5,13 @@ import (
 	"errors"
 	"net"
 	"testing"
+	"time"
 
 	"github.com/golang/mock/gomock"
 	"github.com/qdm12/gluetun/internal/constants/vpn"
 	"github.com/qdm12/gluetun/internal/models"
 	"github.com/qdm12/gluetun/internal/provider/common"
+	"github.com/qdm12/gluetun/internal/updater/resolver"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -28,11 +30,11 @@ func Test_Updater_GetServers(t *testing.T) {
 		unzipErr      error
 
 		// Resolution
-		expectResolve   bool
-		hostsToResolve  []string
-		hostToIPs       map[string][]net.IP
-		resolveWarnings []string
-		resolveErr      error
+		expectResolve    bool
+		resolverSettings resolver.ParallelSettings
+		hostToIPs        map[string][]net.IP
+		resolveWarnings  []string
+		resolveErr       error
 
 		// Output
 		servers []models.Server
@@ -85,9 +87,19 @@ func Test_Updater_GetServers(t *testing.T) {
 			unzipContents: map[string][]byte{
 				"ipvanish-CA-City-A-hosta.ovpn": []byte("remote hosta\nremote hostb"),
 			},
-			expectResolve:  true,
-			hostsToResolve: []string{"hosta"},
-			err:            errors.New("not enough servers found: 0 and expected at least 1"),
+			expectResolve: true,
+			resolverSettings: resolver.ParallelSettings{
+				Hosts:        []string{"hosta"},
+				MaxFailRatio: 0.1,
+				Repeat: resolver.RepeatSettings{
+					MaxDuration:     20 * time.Second,
+					BetweenDuration: time.Second,
+					MaxNoNew:        2,
+					MaxFails:        2,
+					SortIPs:         true,
+				},
+			},
+			err: errors.New("not enough servers found: 0 and expected at least 1"),
 		},
 		"resolve error": {
 			warnerBuilder: func(ctrl *gomock.Controller) common.Warner {
@@ -98,8 +110,18 @@ func Test_Updater_GetServers(t *testing.T) {
 			unzipContents: map[string][]byte{
 				"ipvanish-CA-City-A-hosta.ovpn": []byte("remote hosta"),
 			},
-			expectResolve:   true,
-			hostsToResolve:  []string{"hosta"},
+			expectResolve: true,
+			resolverSettings: resolver.ParallelSettings{
+				Hosts:        []string{"hosta"},
+				MaxFailRatio: 0.1,
+				Repeat: resolver.RepeatSettings{
+					MaxDuration:     20 * time.Second,
+					BetweenDuration: time.Second,
+					MaxNoNew:        2,
+					MaxFails:        2,
+					SortIPs:         true,
+				},
+			},
 			resolveWarnings: []string{"resolve warning"},
 			resolveErr:      errors.New("dummy"),
 			err:             errors.New("dummy"),
@@ -127,8 +149,18 @@ func Test_Updater_GetServers(t *testing.T) {
 				"ipvanish-CA-City-A-hosta.ovpn": []byte("remote hosta"),
 				"ipvanish-LU-City-B-hostb.ovpn": []byte("remote hostb"),
 			},
-			expectResolve:  true,
-			hostsToResolve: []string{"hosta", "hostb"},
+			expectResolve: true,
+			resolverSettings: resolver.ParallelSettings{
+				Hosts:        []string{"hosta", "hostb"},
+				MaxFailRatio: 0.1,
+				Repeat: resolver.RepeatSettings{
+					MaxDuration:     20 * time.Second,
+					BetweenDuration: time.Second,
+					MaxNoNew:        2,
+					MaxFails:        2,
+					SortIPs:         true,
+				},
+			},
 			hostToIPs: map[string][]net.IP{
 				"hosta": {{1, 1, 1, 1}, {2, 2, 2, 2}},
 				"hostb": {{3, 3, 3, 3}, {4, 4, 4, 4}},
@@ -169,7 +201,7 @@ func Test_Updater_GetServers(t *testing.T) {
 
 			presolver := common.NewMockParallelResolver(ctrl)
 			if testCase.expectResolve {
-				presolver.EXPECT().Resolve(ctx, testCase.hostsToResolve, testCase.minServers).
+				presolver.EXPECT().Resolve(ctx, testCase.resolverSettings).
 					Return(testCase.hostToIPs, testCase.resolveWarnings, testCase.resolveErr)
 			}
 

internal/provider/ipvanish/updater/updater.go

@@ -10,10 +10,11 @@ type Updater struct {
 	presolver common.ParallelResolver
 }
 
-func New(unzipper common.Unzipper, warner common.Warner) *Updater {
+func New(unzipper common.Unzipper, warner common.Warner,
+	parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		unzipper:  unzipper,
 		warner:    warner,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 	}
 }

internal/provider/ivpn/connection_test.go

@@ -99,7 +99,8 @@ func Test_Provider_GetConnection(t *testing.T) {
 
 			client := (*http.Client)(nil)
 			warner := (common.Warner)(nil)
-			provider := New(storage, randSource, client, warner)
+			parallelResolver := (common.ParallelResolver)(nil)
+			provider := New(storage, randSource, client, warner, parallelResolver)
 
 			connection, err := provider.GetConnection(testCase.selection)
 

internal/provider/ivpn/provider.go

@@ -18,12 +18,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	client *http.Client, updaterWarner common.Warner) *Provider {
+	client *http.Client, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Ivpn),
-		Fetcher:         updater.New(client, updaterWarner),
+		Fetcher:         updater.New(client, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/ivpn/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 20 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/ivpn/updater/servers.go

@@ -38,7 +38,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 			common.ErrNotEnoughServers, len(hosts), minServers)
 	}
 
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -46,6 +47,11 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
+	if len(hostToIPs) < minServers {
+		return nil, fmt.Errorf("%w: %d and expected at least %d",
+			common.ErrNotEnoughServers, len(servers), minServers)
+	}
+
 	servers = make([]models.Server, 0, len(hosts))
 	for _, serverData := range data.Servers {
 		vpnType := vpn.OpenVPN

internal/provider/ivpn/updater/servers_test.go

@@ -8,11 +8,13 @@ import (
 	"net/http"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/golang/mock/gomock"
 	"github.com/qdm12/gluetun/internal/constants/vpn"
 	"github.com/qdm12/gluetun/internal/models"
 	"github.com/qdm12/gluetun/internal/provider/common"
+	"github.com/qdm12/gluetun/internal/updater/resolver"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -33,7 +35,7 @@ func Test_Updater_GetServers(t *testing.T) {
 
 		// Resolution
 		expectResolve   bool
-		hostsToResolve  []string
+		resolveSettings resolver.ParallelSettings
 		hostToIPs       map[string][]net.IP
 		resolveWarnings []string
 		resolveErr      error
@@ -56,9 +58,19 @@ func Test_Updater_GetServers(t *testing.T) {
 			responseBody: `{"servers":[
 				{"hostnames":{"openvpn":"hosta"}}
 			]}`,
-			responseStatus:  http.StatusOK,
-			expectResolve:   true,
-			hostsToResolve:  []string{"hosta"},
+			responseStatus: http.StatusOK,
+			expectResolve:  true,
+			resolveSettings: resolver.ParallelSettings{
+				Hosts:        []string{"hosta"},
+				MaxFailRatio: 0.1,
+				Repeat: resolver.RepeatSettings{
+					MaxDuration:     20 * time.Second,
+					BetweenDuration: time.Second,
+					MaxNoNew:        2,
+					MaxFails:        2,
+					SortIPs:         true,
+				},
+			},
 			resolveWarnings: []string{"resolve warning"},
 			resolveErr:      errors.New("dummy"),
 			err:             errors.New("dummy"),
@@ -86,7 +98,17 @@ func Test_Updater_GetServers(t *testing.T) {
 			]}`,
 			responseStatus: http.StatusOK,
 			expectResolve:  true,
-			hostsToResolve: []string{"hosta", "hostb", "hostc"},
+			resolveSettings: resolver.ParallelSettings{
+				Hosts:        []string{"hosta", "hostb", "hostc"},
+				MaxFailRatio: 0.1,
+				Repeat: resolver.RepeatSettings{
+					MaxDuration:     20 * time.Second,
+					BetweenDuration: time.Second,
+					MaxNoNew:        2,
+					MaxFails:        2,
+					SortIPs:         true,
+				},
+			},
 			hostToIPs: map[string][]net.IP{
 				"hosta": {{1, 1, 1, 1}, {2, 2, 2, 2}},
 				"hostb": {{3, 3, 3, 3}, {4, 4, 4, 4}},
@@ -130,7 +152,7 @@ func Test_Updater_GetServers(t *testing.T) {
 
 			presolver := common.NewMockParallelResolver(ctrl)
 			if testCase.expectResolve {
-				presolver.EXPECT().Resolve(ctx, testCase.hostsToResolve, testCase.minServers).
+				presolver.EXPECT().Resolve(ctx, testCase.resolveSettings).
 					Return(testCase.hostToIPs, testCase.resolveWarnings, testCase.resolveErr)
 			}
 

internal/provider/ivpn/updater/updater.go

@@ -12,10 +12,11 @@ type Updater struct {
 	warner    common.Warner
 }
 
-func New(client *http.Client, warner common.Warner) *Updater {
+func New(client *http.Client, warner common.Warner,
+	parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		client:    client,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/privado/provider.go

@@ -19,12 +19,13 @@ type Provider struct {
 
 func New(storage common.Storage, randSource rand.Source,
 	client *http.Client, unzipper common.Unzipper,
-	updaterWarner common.Warner) *Provider {
+	updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Privado),
-		Fetcher:         updater.New(client, unzipper, updaterWarner),
+		Fetcher:         updater.New(client, unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/privado/updater/resolve.go

@@ -6,14 +6,15 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio = 0.1
 		maxDuration  = 30 * time.Second
 		maxNoNew     = 2
 		maxFails     = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration: maxDuration,
@@ -22,5 +23,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:     true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/privado/updater/servers.go

@@ -50,7 +50,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	}
 
 	hosts := hts.toHostsSlice()
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -58,6 +59,11 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
+	if len(hostToIPs) < minServers {
+		return nil, fmt.Errorf("%w: %d and expected at least %d",
+			common.ErrNotEnoughServers, len(servers), minServers)
+	}
+
 	hts.adaptWithIPs(hostToIPs)
 
 	servers = hts.toServersSlice()

internal/provider/privado/updater/updater.go

@@ -14,11 +14,11 @@ type Updater struct {
 }
 
 func New(client *http.Client, unzipper common.Unzipper,
-	warner common.Warner) *Updater {
+	warner common.Warner, parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		client:    client,
 		unzipper:  unzipper,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/privatevpn/provider.go

@@ -17,12 +17,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	unzipper common.Unzipper, updaterWarner common.Warner) *Provider {
+	unzipper common.Unzipper, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Privatevpn),
-		Fetcher:         updater.New(unzipper, updaterWarner),
+		Fetcher:         updater.New(unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/privatevpn/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 6 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/privatevpn/updater/servers.go

@@ -82,7 +82,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 
 	hosts := hts.toHostsSlice()
 
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -90,6 +91,11 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
+	if len(noHostnameServers)+len(hostToIPs) < minServers {
+		return nil, fmt.Errorf("%w: %d and expected at least %d",
+			common.ErrNotEnoughServers, len(servers), minServers)
+	}
+
 	hts.adaptWithIPs(hostToIPs)
 
 	servers = hts.toServersSlice()

internal/provider/privatevpn/updater/updater.go

@@ -10,10 +10,11 @@ type Updater struct {
 	warner    common.Warner
 }
 
-func New(unzipper common.Unzipper, warner common.Warner) *Updater {
+func New(unzipper common.Unzipper, warner common.Warner,
+	parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		unzipper:  unzipper,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/protonvpn/provider.go

@@ -18,7 +18,8 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	client *http.Client, updaterWarner common.Warner) *Provider {
+	client *http.Client, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,

internal/provider/providers.go

@@ -44,33 +44,36 @@ type Storage interface {
 }
 
 func NewProviders(storage Storage, timeNow func() time.Time,
-	updaterWarner common.Warner, client *http.Client, unzipper common.Unzipper) *Providers {
+	updaterWarner common.Warner, client *http.Client, unzipper common.Unzipper,
+	parallelResolver common.ParallelResolver) *Providers {
 	randSource := rand.NewSource(timeNow().UnixNano())
 
-	targetLength := len(providers.AllWithCustom())
-	providerNameToProvider := make(map[string]Provider, targetLength)
-	providerNameToProvider[providers.Custom] = custom.New()
-	providerNameToProvider[providers.Cyberghost] = cyberghost.New(storage, randSource)
-	providerNameToProvider[providers.Expressvpn] = expressvpn.New(storage, randSource, unzipper, updaterWarner)
-	providerNameToProvider[providers.Fastestvpn] = fastestvpn.New(storage, randSource, unzipper, updaterWarner)
-	providerNameToProvider[providers.HideMyAss] = hidemyass.New(storage, randSource, client, updaterWarner)
-	providerNameToProvider[providers.Ipvanish] = ipvanish.New(storage, randSource, unzipper, updaterWarner)
-	providerNameToProvider[providers.Ivpn] = ivpn.New(storage, randSource, client, updaterWarner)
-	providerNameToProvider[providers.Mullvad] = mullvad.New(storage, randSource, client)
-	providerNameToProvider[providers.Nordvpn] = nordvpn.New(storage, randSource, client, updaterWarner)
-	providerNameToProvider[providers.Perfectprivacy] = perfectprivacy.New(storage, randSource, unzipper, updaterWarner)
-	providerNameToProvider[providers.Privado] = privado.New(storage, randSource, client, unzipper, updaterWarner)
-	providerNameToProvider[providers.PrivateInternetAccess] = privateinternetaccess.New(storage, randSource, timeNow, client) //nolint:lll
-	providerNameToProvider[providers.Privatevpn] = privatevpn.New(storage, randSource, unzipper, updaterWarner)
-	providerNameToProvider[providers.Protonvpn] = protonvpn.New(storage, randSource, client, updaterWarner)
-	providerNameToProvider[providers.Purevpn] = purevpn.New(storage, randSource, client, unzipper, updaterWarner)
-	providerNameToProvider[providers.Surfshark] = surfshark.New(storage, randSource, client, unzipper, updaterWarner)
-	providerNameToProvider[providers.Torguard] = torguard.New(storage, randSource, unzipper, updaterWarner)
-	providerNameToProvider[providers.VPNUnlimited] = vpnunlimited.New(storage, randSource, unzipper, updaterWarner)
-	providerNameToProvider[providers.Vyprvpn] = vyprvpn.New(storage, randSource, unzipper, updaterWarner)
-	providerNameToProvider[providers.Wevpn] = wevpn.New(storage, randSource, updaterWarner)
-	providerNameToProvider[providers.Windscribe] = windscribe.New(storage, randSource, client, updaterWarner)
+	//nolint:lll
+	providerNameToProvider := map[string]Provider{
+		providers.Custom:                custom.New(),
+		providers.Cyberghost:            cyberghost.New(storage, randSource, parallelResolver),
+		providers.Expressvpn:            expressvpn.New(storage, randSource, unzipper, updaterWarner, parallelResolver),
+		providers.Fastestvpn:            fastestvpn.New(storage, randSource, unzipper, updaterWarner, parallelResolver),
+		providers.HideMyAss:             hidemyass.New(storage, randSource, client, updaterWarner, parallelResolver),
+		providers.Ipvanish:              ipvanish.New(storage, randSource, unzipper, updaterWarner, parallelResolver),
+		providers.Ivpn:                  ivpn.New(storage, randSource, client, updaterWarner, parallelResolver),
+		providers.Mullvad:               mullvad.New(storage, randSource, client),
+		providers.Nordvpn:               nordvpn.New(storage, randSource, client, updaterWarner),
+		providers.Perfectprivacy:        perfectprivacy.New(storage, randSource, unzipper, updaterWarner),
+		providers.Privado:               privado.New(storage, randSource, client, unzipper, updaterWarner, parallelResolver),
+		providers.PrivateInternetAccess: privateinternetaccess.New(storage, randSource, timeNow, client),
+		providers.Privatevpn:            privatevpn.New(storage, randSource, unzipper, updaterWarner, parallelResolver),
+		providers.Protonvpn:             protonvpn.New(storage, randSource, client, updaterWarner, parallelResolver),
+		providers.Purevpn:               purevpn.New(storage, randSource, client, unzipper, updaterWarner, parallelResolver),
+		providers.Surfshark:             surfshark.New(storage, randSource, client, unzipper, updaterWarner, parallelResolver),
+		providers.Torguard:              torguard.New(storage, randSource, unzipper, updaterWarner, parallelResolver),
+		providers.VPNUnlimited:          vpnunlimited.New(storage, randSource, unzipper, updaterWarner, parallelResolver),
+		providers.Vyprvpn:               vyprvpn.New(storage, randSource, unzipper, updaterWarner, parallelResolver),
+		providers.Wevpn:                 wevpn.New(storage, randSource, updaterWarner, parallelResolver),
+		providers.Windscribe:            windscribe.New(storage, randSource, client, updaterWarner),
+	}
 
+	targetLength := len(providers.AllWithCustom())
 	if len(providerNameToProvider) != targetLength {
 		// Programming sanity check
 		panic(fmt.Sprintf("invalid number of providers, expected %d but got %d",

internal/provider/purevpn/provider.go

@@ -18,12 +18,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	client *http.Client, unzipper common.Unzipper, updaterWarner common.Warner) *Provider {
+	client *http.Client, unzipper common.Unzipper, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Purevpn),
-		Fetcher:         updater.New(client, unzipper, updaterWarner),
+		Fetcher:         updater.New(client, unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/purevpn/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 20 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/purevpn/updater/servers.go

@@ -60,7 +60,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	}
 
 	hosts := hts.toHostsSlice()
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -68,15 +69,15 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
-	hts.adaptWithIPs(hostToIPs)
-
-	servers = hts.toServersSlice()
-
-	if len(servers) < minServers {
+	if len(hostToIPs) < minServers {
 		return nil, fmt.Errorf("%w: %d and expected at least %d",
 			common.ErrNotEnoughServers, len(servers), minServers)
 	}
 
+	hts.adaptWithIPs(hostToIPs)
+
+	servers = hts.toServersSlice()
+
 	// Get public IP address information
 	ipsToGetInfo := make([]net.IP, len(servers))
 	for i := range servers {

internal/provider/purevpn/updater/updater.go

@@ -14,11 +14,11 @@ type Updater struct {
 }
 
 func New(client *http.Client, unzipper common.Unzipper,
-	warner common.Warner) *Updater {
+	warner common.Warner, parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		client:    client,
 		unzipper:  unzipper,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/surfshark/provider.go

@@ -18,12 +18,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	client *http.Client, unzipper common.Unzipper, updaterWarner common.Warner) *Provider {
+	client *http.Client, unzipper common.Unzipper, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Surfshark),
-		Fetcher:         updater.New(client, unzipper, updaterWarner),
+		Fetcher:         updater.New(client, unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/surfshark/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 20 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/surfshark/updater/servers.go

@@ -31,7 +31,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	getRemainingServers(hts)
 
 	hosts := hts.toHostsSlice()
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -39,15 +40,15 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
-	hts.adaptWithIPs(hostToIPs)
-
-	servers = hts.toServersSlice()
-
-	if len(servers) < minServers {
+	if len(hostToIPs) < minServers {
 		return nil, fmt.Errorf("%w: %d and expected at least %d",
 			common.ErrNotEnoughServers, len(servers), minServers)
 	}
 
+	hts.adaptWithIPs(hostToIPs)
+
+	servers = hts.toServersSlice()
+
 	sort.Sort(models.SortableServers(servers))
 
 	return servers, nil

internal/provider/surfshark/updater/updater.go

@@ -14,11 +14,11 @@ type Updater struct {
 }
 
 func New(client *http.Client, unzipper common.Unzipper,
-	warner common.Warner) *Updater {
+	warner common.Warner, parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		client:    client,
 		unzipper:  unzipper,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/torguard/provider.go

@@ -17,12 +17,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	unzipper common.Unzipper, updaterWarner common.Warner) *Provider {
+	unzipper common.Unzipper, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Torguard),
-		Fetcher:         updater.New(unzipper, updaterWarner),
+		Fetcher:         updater.New(unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/torguard/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 20 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/torguard/updater/servers.go

@@ -50,12 +50,18 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	}
 
 	hosts := hts.toHostsSlice()
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	u.warnWarnings(warnings)
 	if err != nil {
 		return nil, err
 	}
 
+	if len(hostToIPs) < minServers {
+		return nil, fmt.Errorf("%w: %d and expected at least %d",
+			common.ErrNotEnoughServers, len(servers), minServers)
+	}
+
 	hts.adaptWithIPs(hostToIPs)
 
 	servers = hts.toServersSlice()

internal/provider/torguard/updater/updater.go

@@ -10,10 +10,11 @@ type Updater struct {
 	warner    common.Warner
 }
 
-func New(unzipper common.Unzipper, warner common.Warner) *Updater {
+func New(unzipper common.Unzipper, warner common.Warner,
+	parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		unzipper:  unzipper,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/vpnunlimited/provider.go

@@ -17,12 +17,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	unzipper common.Unzipper, updaterWarner common.Warner) *Provider {
+	unzipper common.Unzipper, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.VPNUnlimited),
-		Fetcher:         updater.New(unzipper, updaterWarner),
+		Fetcher:         updater.New(unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/vpnunlimited/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 20 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/vpnunlimited/updater/servers.go

@@ -20,7 +20,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	}
 
 	hosts := hts.toHostsSlice()
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -28,15 +29,15 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
-	hts.adaptWithIPs(hostToIPs)
-
-	servers = hts.toServersSlice()
-
-	if len(servers) < minServers {
+	if len(hostToIPs) < minServers {
 		return nil, fmt.Errorf("%w: %d and expected at least %d",
 			common.ErrNotEnoughServers, len(servers), minServers)
 	}
 
+	hts.adaptWithIPs(hostToIPs)
+
+	servers = hts.toServersSlice()
+
 	sort.Sort(models.SortableServers(servers))
 
 	return servers, nil

internal/provider/vpnunlimited/updater/updater.go

@@ -10,10 +10,11 @@ type Updater struct {
 	warner    common.Warner
 }
 
-func New(unzipper common.Unzipper, warner common.Warner) *Updater {
+func New(unzipper common.Unzipper, warner common.Warner,
+	parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		unzipper:  unzipper,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/vyprvpn/provider.go

@@ -17,12 +17,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	unzipper common.Unzipper, updaterWarner common.Warner) *Provider {
+	unzipper common.Unzipper, updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Vyprvpn),
-		Fetcher:         updater.New(unzipper, updaterWarner),
+		Fetcher:         updater.New(unzipper, updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/vyprvpn/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 5 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/vyprvpn/updater/servers.go

@@ -64,7 +64,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	}
 
 	hosts := hts.toHostsSlice()
-	hostToIPs, warnings, err := u.presolver.Resolve(ctx, hosts, minServers)
+	resolveSettings := parallelResolverSettings(hosts)
+	hostToIPs, warnings, err := u.presolver.Resolve(ctx, resolveSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}
@@ -72,15 +73,15 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		return nil, err
 	}
 
-	hts.adaptWithIPs(hostToIPs)
-
-	servers = hts.toServersSlice()
-
-	if len(servers) < minServers {
+	if len(hostToIPs) < minServers {
 		return nil, fmt.Errorf("%w: %d and expected at least %d",
 			common.ErrNotEnoughServers, len(servers), minServers)
 	}
 
+	hts.adaptWithIPs(hostToIPs)
+
+	servers = hts.toServersSlice()
+
 	sort.Sort(models.SortableServers(servers))
 
 	return servers, nil

internal/provider/vyprvpn/updater/updater.go

@@ -10,10 +10,11 @@ type Updater struct {
 	warner    common.Warner
 }
 
-func New(unzipper common.Unzipper, warner common.Warner) *Updater {
+func New(unzipper common.Unzipper, warner common.Warner,
+	parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
 		unzipper:  unzipper,
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/provider/wevpn/connection_test.go

@@ -93,7 +93,8 @@ func Test_Provider_GetConnection(t *testing.T) {
 			randSource := rand.NewSource(0)
 
 			warner := (common.Warner)(nil)
-			provider := New(storage, randSource, warner)
+			parallelResolver := (common.ParallelResolver)(nil)
+			provider := New(storage, randSource, warner, parallelResolver)
 
 			if testCase.panicMessage != "" {
 				assert.PanicsWithValue(t, testCase.panicMessage, func() {

internal/provider/wevpn/provider.go

@@ -17,12 +17,13 @@ type Provider struct {
 }
 
 func New(storage common.Storage, randSource rand.Source,
-	updaterWarner common.Warner) *Provider {
+	updaterWarner common.Warner,
+	parallelResolver common.ParallelResolver) *Provider {
 	return &Provider{
 		storage:         storage,
 		randSource:      randSource,
 		NoPortForwarder: utils.NewNoPortForwarding(providers.Wevpn),
-		Fetcher:         updater.New(updaterWarner),
+		Fetcher:         updater.New(updaterWarner, parallelResolver),
 	}
 }
 

internal/provider/wevpn/updater/resolve.go

@@ -6,7 +6,7 @@ import (
 	"github.com/qdm12/gluetun/internal/updater/resolver"
 )
 
-func newParallelResolver() (parallelResolver *resolver.Parallel) {
+func parallelResolverSettings(hosts []string) (settings resolver.ParallelSettings) {
 	const (
 		maxFailRatio    = 0.1
 		maxDuration     = 20 * time.Second
@@ -14,7 +14,8 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 		maxNoNew        = 2
 		maxFails        = 2
 	)
-	settings := resolver.ParallelSettings{
+	return resolver.ParallelSettings{
+		Hosts:        hosts,
 		MaxFailRatio: maxFailRatio,
 		Repeat: resolver.RepeatSettings{
 			MaxDuration:     maxDuration,
@@ -24,5 +25,4 @@ func newParallelResolver() (parallelResolver *resolver.Parallel) {
 			SortIPs:         true,
 		},
 	}
-	return resolver.NewParallelResolver(settings)
 }

internal/provider/wevpn/updater/servers.go

@@ -31,7 +31,8 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 		hostnameToCity[hostname] = city
 	}
 
-	hostnameToIPs, warnings, err := u.presolver.Resolve(ctx, hostnames, minServers)
+	resolverSettings := parallelResolverSettings(hostnames)
+	hostnameToIPs, warnings, err := u.presolver.Resolve(ctx, resolverSettings)
 	for _, warning := range warnings {
 		u.warner.Warn(warning)
 	}

internal/provider/wevpn/updater/updater.go

@@ -7,9 +7,9 @@ type Updater struct {
 	warner    common.Warner
 }
 
-func New(warner common.Warner) *Updater {
+func New(warner common.Warner, parallelResolver common.ParallelResolver) *Updater {
 	return &Updater{
-		presolver: newParallelResolver(),
+		presolver: parallelResolver,
 		warner:    warner,
 	}
 }

internal/updater/resolver/parallel.go

@@ -9,17 +9,17 @@ import (
 
 type Parallel struct {
 	repeatResolver *Repeat
-	settings       ParallelSettings
 }
 
-func NewParallelResolver(settings ParallelSettings) *Parallel {
+func NewParallelResolver(resolverAddress string) *Parallel {
 	return &Parallel{
-		repeatResolver: NewRepeat(settings.Repeat),
-		settings:       settings,
+		repeatResolver: NewRepeat(resolverAddress),
 	}
 }
 
 type ParallelSettings struct {
+	// Hosts to resolve in parallel.
+	Hosts     []string
 	Repeat    RepeatSettings
 	FailEarly bool
 	// Maximum ratio of the hosts failing DNS resolution
@@ -39,7 +39,7 @@ var (
 	ErrMaxFailRatio = errors.New("maximum failure ratio reached")
 )
 
-func (pr *Parallel) Resolve(ctx context.Context, hosts []string, minToFind int) (
+func (pr *Parallel) Resolve(ctx context.Context, settings ParallelSettings) (
 	hostToIPs map[string][]net.IP, warnings []string, err error) {
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
@@ -49,17 +49,17 @@ func (pr *Parallel) Resolve(ctx context.Context, hosts []string, minToFind int)
 	errors := make(chan error)
 	defer close(errors)
 
-	for _, host := range hosts {
-		go pr.resolveAsync(ctx, host, results, errors)
+	for _, host := range settings.Hosts {
+		go pr.resolveAsync(ctx, host, settings.Repeat, results, errors)
 	}
 
-	hostToIPs = make(map[string][]net.IP, len(hosts))
-	maxFails := int(pr.settings.MaxFailRatio * float64(len(hosts)))
+	hostToIPs = make(map[string][]net.IP, len(settings.Hosts))
+	maxFails := int(settings.MaxFailRatio * float64(len(settings.Hosts)))
 
-	for range hosts {
+	for range settings.Hosts {
 		select {
 		case newErr := <-errors:
-			if pr.settings.FailEarly {
+			if settings.FailEarly {
 				if err == nil {
 					// only set the error to the first error encountered
 					// and not the context canceled errors coming after.
@@ -86,14 +86,8 @@ func (pr *Parallel) Resolve(ctx context.Context, hosts []string, minToFind int)
 		return nil, warnings, err
 	}
 
-	if len(hostToIPs) < minToFind {
-		return nil, warnings,
-			fmt.Errorf("%w: found %d hosts but expected at least %d",
-				ErrMinFound, len(hostToIPs), minToFind)
-	}
-
-	failureRatio := float64(len(warnings)) / float64(len(hosts))
-	if failureRatio > pr.settings.MaxFailRatio {
+	failureRatio := float64(len(warnings)) / float64(len(settings.Hosts))
+	if failureRatio > settings.MaxFailRatio {
 		return hostToIPs, warnings,
 			fmt.Errorf("%w: %.2f failure ratio reached", ErrMaxFailRatio, failureRatio)
 	}
@@ -102,8 +96,8 @@ func (pr *Parallel) Resolve(ctx context.Context, hosts []string, minToFind int)
 }
 
 func (pr *Parallel) resolveAsync(ctx context.Context, host string,
-	results chan<- parallelResult, errors chan<- error) {
-	IPs, err := pr.repeatResolver.Resolve(ctx, host)
+	settings RepeatSettings, results chan<- parallelResult, errors chan<- error) {
+	IPs, err := pr.repeatResolver.Resolve(ctx, host, settings)
 	if err != nil {
 		errors <- err
 		return

internal/updater/resolver/repeat.go

@@ -12,13 +12,11 @@ import (
 
 type Repeat struct {
 	resolver *net.Resolver
-	settings RepeatSettings
 }
 
-func NewRepeat(settings RepeatSettings) *Repeat {
+func NewRepeat(resolverAddress string) *Repeat {
 	return &Repeat{
-		resolver: newResolver(settings.Address),
-		settings: settings,
+		resolver: newResolver(resolverAddress),
 	}
 }
 
@@ -32,8 +30,9 @@ type RepeatSettings struct {
 	SortIPs  bool
 }
 
-func (r *Repeat) Resolve(ctx context.Context, host string) (ips []net.IP, err error) {
-	timedCtx, cancel := context.WithTimeout(ctx, r.settings.MaxDuration)
+func (r *Repeat) Resolve(ctx context.Context, host string, settings RepeatSettings) (
+	ips []net.IP, err error) {
+	timedCtx, cancel := context.WithTimeout(ctx, settings.MaxDuration)
 	defer cancel()
 
 	noNewCounter := 0
@@ -44,7 +43,7 @@ func (r *Repeat) Resolve(ctx context.Context, host string) (ips []net.IP, err er
 		// TODO
 		// - one resolving every 100ms for round robin DNS responses
 		// - one every second for time based DNS cycling responses
-		noNewCounter, failCounter, err = r.resolveOnce(ctx, timedCtx, host, r.settings, uniqueIPs, noNewCounter, failCounter)
+		noNewCounter, failCounter, err = r.resolveOnce(ctx, timedCtx, host, settings, uniqueIPs, noNewCounter, failCounter)
 	}
 
 	if len(uniqueIPs) == 0 {
@@ -53,7 +52,7 @@ func (r *Repeat) Resolve(ctx context.Context, host string) (ips []net.IP, err er
 
 	ips = uniqueIPsToSlice(uniqueIPs)
 
-	if r.settings.SortIPs {
+	if settings.SortIPs {
 		sort.Slice(ips, func(i, j int) bool {
 			return bytes.Compare(ips[i], ips[j]) < 1
 		})