feat(health): HEALTH_RESTART_VPN option

- You should really leave it to `on` ⚠️
- Turn it to `off` if you have trust issues with the healthcheck. Don't then report issues if the connection is dead though.

Dockerfile

@@ -165,6 +165,7 @@ ENV VPN_SERVICE_PROVIDER=pia \
     HEALTH_SERVER_ADDRESS=127.0.0.1:9999 \
     HEALTH_TARGET_ADDRESS=cloudflare.com:443 \
     HEALTH_ICMP_TARGET_IP=0.0.0.0 \
+    HEALTH_RESTART_VPN=on \
     # DNS over TLS
     DOT=on \
     DOT_PROVIDERS=cloudflare \

internal/configuration/settings/health.go

@@ -32,6 +32,9 @@ type Health struct {
 	// in the health checker. It can be set to an unspecified address
 	// such that the VPN server IP is used, which is also the default behavior.
 	ICMPTargetIP netip.Addr
+	// RestartVPN indicates whether to restart the VPN connection
+	// when the healthcheck fails.
+	RestartVPN *bool
 }
 
 func (h Health) Validate() (err error) {
@@ -50,6 +53,7 @@ func (h *Health) copy() (copied Health) {
 		ReadTimeout:       h.ReadTimeout,
 		TargetAddress:     h.TargetAddress,
 		ICMPTargetIP:      h.ICMPTargetIP,
+		RestartVPN:        gosettings.CopyPointer(h.RestartVPN),
 	}
 }
 
@@ -62,6 +66,7 @@ func (h *Health) OverrideWith(other Health) {
 	h.ReadTimeout = gosettings.OverrideWithComparable(h.ReadTimeout, other.ReadTimeout)
 	h.TargetAddress = gosettings.OverrideWithComparable(h.TargetAddress, other.TargetAddress)
 	h.ICMPTargetIP = gosettings.OverrideWithComparable(h.ICMPTargetIP, other.ICMPTargetIP)
+	h.RestartVPN = gosettings.OverrideWithPointer(h.RestartVPN, other.RestartVPN)
 }
 
 func (h *Health) SetDefaults() {
@@ -72,6 +77,7 @@ func (h *Health) SetDefaults() {
 	h.ReadTimeout = gosettings.DefaultComparable(h.ReadTimeout, defaultReadTimeout)
 	h.TargetAddress = gosettings.DefaultComparable(h.TargetAddress, "cloudflare.com:443")
 	h.ICMPTargetIP = gosettings.DefaultComparable(h.ICMPTargetIP, netip.IPv4Unspecified()) // use the VPN server IP
+	h.RestartVPN = gosettings.DefaultPointer(h.RestartVPN, true)
 }
 
 func (h Health) String() string {
@@ -87,6 +93,7 @@ func (h Health) toLinesNode() (node *gotree.Node) {
 		icmpTarget = h.ICMPTargetIP.String()
 	}
 	node.Appendf("ICMP target IP: %s", icmpTarget)
+	node.Appendf("Restart VPN on healthcheck failure: %s", gosettings.BoolToYesNo(h.RestartVPN))
 	return node
 }
 
@@ -98,5 +105,9 @@ func (h *Health) Read(r *reader.Reader) (err error) {
 	if err != nil {
 		return err
 	}
+	h.RestartVPN, err = r.BoolPtr("HEALTH_RESTART_VPN")
+	if err != nil {
+		return err
+	}
 	return nil
 }

internal/configuration/settings/settings_test.go

@@ -58,7 +58,8 @@ func Test_Settings_String(t *testing.T) {
 ├── Health settings:
 |   ├── Server listening address: 127.0.0.1:9999
 |   ├── Target address: cloudflare.com:443
-|   └── ICMP target IP: VPN server IP
+|   ├── ICMP target IP: VPN server IP
+|   └── Restart VPN on healthcheck failure: yes
 ├── Shadowsocks server settings:
 |   └── Enabled: no
 ├── HTTP proxy settings:

internal/healthcheck/checker.go

@@ -59,8 +59,9 @@ func (c *Checker) SetConfig(tlsDialAddr string, icmpTarget netip.Addr) {
 // and, on success, starts the periodic checks in a separate goroutine:
 // - a "small" ICMP echo check every 15 seconds
 // - a "full" TCP+TLS check every 5 minutes
-// It returns a channel `runError` that receives an error if one of the periodic checks fail.
+// It returns a channel `runError` that receives an error (nil or not) when a periodic check is performed.
 // It returns an error if the initial TCP+TLS check fails.
+// The Checker has to be ultimately stopped by calling [Checker.Stop].
 func (c *Checker) Start(ctx context.Context) (runError <-chan error, err error) {
 	if c.tlsDialAddr == "" || c.icmpTarget.IsUnspecified() {
 		panic("call Checker.SetConfig with non empty values before Checker.Start")
@@ -101,16 +102,16 @@ func (c *Checker) Start(ctx context.Context) (runError <-chan error, err error)
 			case <-smallCheckTimer.C:
 				err := c.smallPeriodicCheck(ctx)
 				if err != nil {
-					runErrorCh <- fmt.Errorf("periodic small check: %w", err)
-					return
+					err = fmt.Errorf("small periodic check: %w", err)
 				}
+				runErrorCh <- err
 				smallCheckTimer.Reset(smallCheckPeriod)
 			case <-fullCheckTimer.C:
 				err := c.fullPeriodicCheck(ctx)
 				if err != nil {
-					runErrorCh <- fmt.Errorf("periodic full check: %w", err)
-					return
+					err = fmt.Errorf("full periodic check: %w", err)
 				}
+				runErrorCh <- err
 				fullCheckTimer.Reset(fullCheckPeriod)
 			}
 		}

internal/vpn/tunnelup.go

@@ -45,9 +45,6 @@ func (l *Loop) onTunnelUp(ctx, loopCtx context.Context, data tunnelUpData) {
 		l.restartVPN(loopCtx, err)
 		return
 	}
-	defer func() {
-		_ = l.healthChecker.Stop()
-	}()
 
 	if *l.dnsLooper.GetSettings().DoT.Enabled {
 		_, _ = l.dnsLooper.ApplyStatus(ctx, constants.Running)
@@ -78,13 +75,25 @@ func (l *Loop) onTunnelUp(ctx, loopCtx context.Context, data tunnelUpData) {
 		l.logger.Error(err.Error())
 	}
 
-	select {
-	case <-ctx.Done():
-	case healthErr := <-healthErrCh:
-		l.healthServer.SetError(healthErr)
-		// Note this restart call must be done in a separate goroutine
-		// from the VPN loop goroutine.
-		l.restartVPN(loopCtx, healthErr)
+	for {
+		select {
+		case <-ctx.Done():
+			_ = l.healthChecker.Stop()
+			return
+		case healthErr := <-healthErrCh:
+			l.healthServer.SetError(healthErr)
+			if healthErr != nil {
+				if *l.healthSettings.RestartVPN {
+					// Note this restart call must be done in a separate goroutine
+					// from the VPN loop goroutine.
+					_ = l.healthChecker.Stop()
+					l.restartVPN(loopCtx, healthErr)
+					return
+				}
+				l.logger.Warnf("healthcheck failed: %s", healthErr)
+				l.logger.Info("👉 See https://github.com/qdm12/gluetun-wiki/blob/main/faq/healthcheck.md")
+			}
+		}
 	}
 }