feat(health): add check endpoint and loop control

Dockerfile

@@ -161,6 +161,7 @@ ENV VPN_SERVICE_PROVIDER=pia \
     LOG_LEVEL=info \
     # Health
     HEALTH_SERVER_ADDRESS=127.0.0.1:9999 \
+    HEALTH_SERVER_DISABLE_LOOP=off \
     HEALTH_TARGET_ADDRESS=cloudflare.com:443 \
     HEALTH_SUCCESS_WAIT_DURATION=5s \
     HEALTH_VPN_DURATION_INITIAL=6s \

internal/configuration/settings/health.go

@@ -34,6 +34,8 @@ type Health struct {
 	SuccessWait time.Duration
 	// VPN has health settings specific to the VPN loop.
 	VPN HealthyWait
+	// Disable the healthcheck server loop. Useful for environments like Kubernetes which have their own healthcheck loops.
+	DisableLoop *bool
 }
 
 func (h Health) Validate() (err error) {
@@ -58,6 +60,7 @@ func (h *Health) copy() (copied Health) {
 		TargetAddress:     h.TargetAddress,
 		SuccessWait:       h.SuccessWait,
 		VPN:               h.VPN.copy(),
+		DisableLoop:       gosettings.CopyPointer(h.DisableLoop),
 	}
 }
 
@@ -71,6 +74,7 @@ func (h *Health) OverrideWith(other Health) {
 	h.TargetAddress = gosettings.OverrideWithComparable(h.TargetAddress, other.TargetAddress)
 	h.SuccessWait = gosettings.OverrideWithComparable(h.SuccessWait, other.SuccessWait)
 	h.VPN.overrideWith(other.VPN)
+	h.DisableLoop = gosettings.OverrideWithPointer(h.DisableLoop, other.DisableLoop)
 }
 
 func (h *Health) SetDefaults() {
@@ -83,6 +87,7 @@ func (h *Health) SetDefaults() {
 	const defaultSuccessWait = 5 * time.Second
 	h.SuccessWait = gosettings.DefaultComparable(h.SuccessWait, defaultSuccessWait)
 	h.VPN.setDefaults()
+	h.DisableLoop = gosettings.DefaultPointer(h.DisableLoop, false)
 }
 
 func (h Health) String() string {
@@ -97,23 +102,25 @@ func (h Health) toLinesNode() (node *gotree.Node) {
 	node.Appendf("Read header timeout: %s", h.ReadHeaderTimeout)
 	node.Appendf("Read timeout: %s", h.ReadTimeout)
 	node.AppendNode(h.VPN.toLinesNode("VPN"))
+	node.Appendf("Disable loop: %s", gosettings.BoolToYesNo(h.DisableLoop))
 	return node
 }
 
 func (h *Health) Read(r *reader.Reader) (err error) {
 	h.ServerAddress = r.String("HEALTH_SERVER_ADDRESS")
 	h.TargetAddress = r.String("HEALTH_TARGET_ADDRESS",
 		reader.RetroKeys("HEALTH_ADDRESS_TO_PING"))
-
 	h.SuccessWait, err = r.Duration("HEALTH_SUCCESS_WAIT_DURATION")
 	if err != nil {
 		return err
 	}
-
 	err = h.VPN.read(r)
 	if err != nil {
 		return fmt.Errorf("VPN health settings: %w", err)
 	}
-
+	h.DisableLoop, err = r.BoolPtr("HEALTH_SERVER_DISABLE_LOOP")
+	if err != nil {
+		return err
+	}
 	return nil
 }

internal/healthcheck/run.go

@@ -11,11 +11,15 @@ func (s *Server) Run(ctx context.Context, done chan<- struct{}) {
 	defer close(done)
 
 	loopDone := make(chan struct{})
-	go s.runHealthcheckLoop(ctx, loopDone)
+	if !*s.config.DisableLoop {
+		go s.runHealthcheckLoop(ctx, loopDone)
+	} else {
+		close(done)
+	}
 
 	server := http.Server{
 		Addr:              s.config.ServerAddress,
-		Handler:           s.handler,
+		Handler:           s.mux,
 		ReadHeaderTimeout: s.config.ReadHeaderTimeout,
 		ReadTimeout:       s.config.ReadTimeout,
 	}

internal/healthcheck/server.go

@@ -3,6 +3,7 @@ package healthcheck
 import (
 	"context"
 	"net"
+	"net/http"
 
 	"github.com/qdm12/gluetun/internal/configuration/settings"
 	"github.com/qdm12/gluetun/internal/models"
@@ -14,12 +15,13 @@ type Server struct {
 	dialer  *net.Dialer
 	config  settings.Health
 	vpn     vpnHealth
+	mux     *http.ServeMux
 }
 
 func NewServer(config settings.Health,
 	logger Logger, vpnLoop StatusApplier,
 ) *Server {
-	return &Server{
+	s := &Server{
 		logger:  logger,
 		handler: newHandler(),
 		dialer: &net.Dialer{
@@ -32,7 +34,18 @@ func NewServer(config settings.Health,
 			loop:        vpnLoop,
 			healthyWait: *config.VPN.Initial,
 		},
+		mux: http.NewServeMux(),
 	}
+	s.mux.Handle("/", s.handler)
+	s.mux.HandleFunc("/check/", func(w http.ResponseWriter, r *http.Request) {
+		err := s.healthCheck(r.Context())
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+	})
+	return s
 }
 
 type StatusApplier interface {