Add more extensive healthcheck support

- Add new cli argument: -healthcheck
- Add HEALTHCHECK instruction to Dockerfile
- Update Docker Compose examples

cli/cli.go

@@ -28,6 +28,7 @@ const (
 	flagDebugModeHelp       = "Show debug logs"
 	flagConfigFileHelp      = "Load configuration file"
 	flagConfigDumpHelp      = "Print parsed configuration values"
+	flagHealthCheckHelp     = `Perform a health check on the given endpoint (the value "auto" try to guess the health check endpoint).`
 )
 
 // Parse parses command line arguments.
@@ -44,6 +45,7 @@ func Parse() {
 		flagDebugMode       bool
 		flagConfigFile      string
 		flagConfigDump      bool
+		flagHealthCheck     string
 	)
 
 	flag.BoolVar(&flagInfo, "info", false, flagInfoHelp)
@@ -59,6 +61,7 @@ func Parse() {
 	flag.StringVar(&flagConfigFile, "config-file", "", flagConfigFileHelp)
 	flag.StringVar(&flagConfigFile, "c", "", flagConfigFileHelp)
 	flag.BoolVar(&flagConfigDump, "config-dump", false, flagConfigDumpHelp)
+	flag.StringVar(&flagHealthCheck, "healthcheck", "", flagHealthCheckHelp)
 	flag.Parse()
 
 	cfg := config.NewParser()
@@ -88,6 +91,11 @@ func Parse() {
 		logger.EnableDebug()
 	}
 
+	if flagHealthCheck != "" {
+		doHealthCheck(flagHealthCheck)
+		return
+	}
+
 	if flagInfo {
 		info()
 		return

cli/health_check.go

@@ -0,0 +1,34 @@
+// Copyright 2021 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package cli // import "miniflux.app/cli"
+
+import (
+	"net/http"
+	"time"
+
+	"miniflux.app/config"
+	"miniflux.app/logger"
+)
+
+func doHealthCheck(healthCheckEndpoint string) {
+	if healthCheckEndpoint == "auto" {
+		healthCheckEndpoint = "http://" + config.Opts.ListenAddr() + config.Opts.BasePath() + "/healthcheck"
+	}
+
+	logger.Debug(`Executing health check on %s`, healthCheckEndpoint)
+
+	client := &http.Client{Timeout: 3 * time.Second}
+	resp, err := client.Get(healthCheckEndpoint)
+	if err != nil {
+		logger.Fatal(`Health check failure: %v`, err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		logger.Fatal(`Health check failed with status code %d`, resp.StatusCode)
+	}
+
+	logger.Debug(`Health check is OK`)
+}