feat(pprof): add pprof HTTP server (#807)

- `PPROF_ENABLED=no`
- `PPROF_BLOCK_PROFILE_RATE=0`
- `PPROF_MUTEX_PROFILE_RATE=0`
- `PPROF_HTTP_SERVER_ADDRESS=":6060"`

internal/pprof/settings.go

@@ -0,0 +1,96 @@
+package pprof
+
+import (
+	"errors"
+
+	"github.com/qdm12/gluetun/internal/configuration/settings/helpers"
+	"github.com/qdm12/gluetun/internal/httpserver"
+	"github.com/qdm12/gotree"
+)
+
+// Settings are the settings for the Pprof service.
+type Settings struct {
+	// Enabled can be false or true.
+	// It defaults to false.
+	Enabled *bool
+	// See runtime.SetBlockProfileRate
+	// Set to 0 to disable profiling.
+	BlockProfileRate int
+	// See runtime.SetMutexProfileFraction
+	// Set to 0 to disable profiling.
+	MutexProfileRate int
+	// HTTPServer contains settings to configure
+	// the HTTP server serving pprof data.
+	HTTPServer httpserver.Settings
+}
+
+func (s *Settings) SetDefaults() {
+	s.Enabled = helpers.DefaultBool(s.Enabled, false)
+	s.HTTPServer.Name = helpers.DefaultStringPtr(s.HTTPServer.Name, "pprof")
+	s.HTTPServer.Address = helpers.DefaultString(s.HTTPServer.Address, "localhost:6060")
+	s.HTTPServer.SetDefaults()
+}
+
+func (s Settings) Copy() (copied Settings) {
+	return Settings{
+		Enabled:          helpers.CopyBoolPtr(s.Enabled),
+		BlockProfileRate: s.BlockProfileRate,
+		MutexProfileRate: s.MutexProfileRate,
+		HTTPServer:       s.HTTPServer.Copy(),
+	}
+}
+
+func (s *Settings) MergeWith(other Settings) {
+	s.Enabled = helpers.MergeWithBool(s.Enabled, other.Enabled)
+	s.BlockProfileRate = helpers.MergeWithInt(s.BlockProfileRate, other.BlockProfileRate)
+	s.MutexProfileRate = helpers.MergeWithInt(s.MutexProfileRate, other.MutexProfileRate)
+	s.HTTPServer.MergeWith(other.HTTPServer)
+}
+
+func (s *Settings) OverrideWith(other Settings) {
+	s.Enabled = helpers.OverrideWithBool(s.Enabled, other.Enabled)
+	s.BlockProfileRate = helpers.OverrideWithInt(s.BlockProfileRate, other.BlockProfileRate)
+	s.MutexProfileRate = helpers.OverrideWithInt(s.MutexProfileRate, other.MutexProfileRate)
+	s.HTTPServer.OverrideWith(other.HTTPServer)
+}
+
+var (
+	ErrBlockProfileRateNegative = errors.New("block profile rate cannot be negative")
+	ErrMutexProfileRateNegative = errors.New("mutex profile rate cannot be negative")
+)
+
+func (s Settings) Validate() (err error) {
+	if s.BlockProfileRate < 0 {
+		return ErrBlockProfileRateNegative
+	}
+
+	if s.MutexProfileRate < 0 {
+		return ErrMutexProfileRateNegative
+	}
+
+	return s.HTTPServer.Validate()
+}
+
+func (s Settings) ToLinesNode() (node *gotree.Node) {
+	if !*s.Enabled {
+		return nil
+	}
+
+	node = gotree.New("Pprof settings:")
+
+	if s.BlockProfileRate > 0 {
+		node.Appendf("Block profile rate: %d", s.BlockProfileRate)
+	}
+
+	if s.MutexProfileRate > 0 {
+		node.Appendf("Mutex profile rate: %d", s.MutexProfileRate)
+	}
+
+	node.AppendNode(s.HTTPServer.ToLinesNode())
+
+	return node
+}
+
+func (s Settings) String() string {
+	return s.ToLinesNode().String()
+}