Adds a simple healthcheck every 2s (#1814)

* Adds a simple healthcheck every 5s

* Fixes bugs for healthcheck

Dockerfile

@@ -34,6 +34,7 @@ COPY --from=node /build/dist ./dist
 
 # Copy all other files
 COPY analytics ./analytics
+COPY healthcheck ./healthcheck
 COPY docker ./docker
 COPY web ./web
 COPY main.go ./
@@ -56,6 +57,8 @@ ENV PATH /bin
 COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
 COPY --from=upx /dozzle /dozzle
 
+HEALTHCHECK --start-period=4s --interval=2s CMD [ "/dozzle", "healthcheck" ]
+
 EXPOSE 8080
 
 ENTRYPOINT ["/dozzle"]

docker/client.go

@@ -28,6 +28,7 @@ type dockerProxy interface {
 	Events(context.Context, types.EventsOptions) (<-chan events.Message, <-chan error)
 	ContainerInspect(ctx context.Context, containerID string) (types.ContainerJSON, error)
 	ContainerStats(ctx context.Context, containerID string, stream bool) (types.ContainerStats, error)
+	Ping(ctx context.Context) (types.Ping, error)
 }
 
 // Client is a proxy around the docker client
@@ -38,6 +39,7 @@ type Client interface {
 	Events(context.Context) (<-chan ContainerEvent, <-chan error)
 	ContainerLogsBetweenDates(context.Context, string, time.Time, time.Time) (io.ReadCloser, error)
 	ContainerStats(context.Context, string, chan<- ContainerStat) error
+	Ping(context.Context) (types.Ping, error)
 }
 
 // NewClientWithFilters creates a new instance of Client with docker filters
@@ -241,3 +243,7 @@ func (d *dockerClient) ContainerLogsBetweenDates(ctx context.Context, id string,
 
 	return newLogReader(reader, containerJSON.Config.Tty), nil
 }
+
+func (d *dockerClient) Ping(ctx context.Context) (types.Ping, error) {
+	return d.cli.Ping(ctx)
+}

healthcheck/http.go

@@ -0,0 +1,32 @@
+package healthcheck
+
+import (
+	"fmt"
+	log "github.com/sirupsen/logrus"
+	"net/http"
+	"os"
+	"strings"
+)
+
+func HttpRequest(addr string, base string) error {
+	if strings.HasPrefix(addr, ":") {
+		addr = "localhost" + addr
+	}
+
+	url := fmt.Sprintf("http://%s%s/healthcheck", addr, base)
+	log.Info("Checking health of " + url)
+	resp, err := http.Get(url)
+
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == 200 {
+		os.Exit(0)
+	}
+
+	os.Exit(1)
+
+	return nil
+}

main.go

@@ -15,6 +15,7 @@ import (
 	"github.com/alexflint/go-arg"
 	"github.com/amir20/dozzle/analytics"
 	"github.com/amir20/dozzle/docker"
+	"github.com/amir20/dozzle/healthcheck"
 	"github.com/amir20/dozzle/web"
 
 	log "github.com/sirupsen/logrus"
@@ -35,6 +36,10 @@ type args struct {
 	WaitForDockerSeconds int                 `arg:"--wait-for-docker-seconds,env:DOZZLE_WAIT_FOR_DOCKER_SECONDS" help:"wait for docker to be available for at most this many seconds before starting the server."`
 	FilterStrings        []string            `arg:"env:DOZZLE_FILTER,--filter,separate" help:"filters docker containers using Docker syntax."`
 	Filter               map[string][]string `arg:"-"`
+	Healthcheck          *HealthcheckCmd     `arg:"subcommand:healthcheck" help:"checks if the server is running."`
+}
+
+type HealthcheckCmd struct {
 }
 
 func (args) Version() string {
@@ -68,6 +73,12 @@ func main() {
 		DisableLevelTruncation: true,
 	})
 
+	if args.Healthcheck != nil {
+		if err := healthcheck.HttpRequest(args.Addr, args.Base); err != nil {
+			log.Fatal(err)
+		}
+	}
+
 	log.Infof("Dozzle version %s", version)
 	dockerClient := docker.NewClientWithFilters(args.Filter)
 	for i := 1; ; i++ {

web/routes.go

@@ -61,6 +61,7 @@ func createRouter(h *handler) *mux.Router {
 	s.HandleFunc("/api/validateCredentials", h.validateCredentials)
 	s.Handle("/logout", authorizationRequired(h.clearSession))
 	s.Handle("/version", authorizationRequired(h.version))
+	s.HandleFunc("/healthcheck", h.healthcheck)
 
 	if log.IsLevelEnabled(log.DebugLevel) {
 		s.PathPrefix("/debug/pprof/").Handler(http.DefaultServeMux)
@@ -131,3 +132,14 @@ func (h *handler) version(w http.ResponseWriter, r *http.Request) {
 	w.Header().Add("Content-Type", "text/html")
 	fmt.Fprintf(w, "<pre>%v</pre>", h.config.Version)
 }
+
+func (h *handler) healthcheck(w http.ResponseWriter, r *http.Request) {
+	log.Trace("Executing healthcheck request")
+
+	if ping, err := h.client.Ping(r.Context()); err != nil {
+		log.Error(err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+	} else {
+		fmt.Fprintf(w, "OK API Version %v", ping.APIVersion)
+	}
+}