Configurable and very basic health check endpoint

README.md

@@ -176,6 +176,10 @@ After start-up you can connect to the server and explore the published tables an
 
 To disable the web interface, supply the run time flag `--no-preview`
 
+## Health Check Endpoint
+
+In order to run the server in an orchestrated environment, like Docker, it can be useful to have a health check endpoint. This is `/health` by default, and returns a `200 OK` if the server is responding to requests. To use a custom URL for the health check endpoint, supply the run time flag `-e` and your path. This setting will respect the base path setting, so if you choose a base path of `/example` and a health check endpoint of `/foo`, your health check URL becomes `/example/foo`.
+
 ## Layers List
 
 A list of layers is available in JSON at:

main.go

@@ -100,6 +100,8 @@ func init() {
 	viper.SetDefault("CoordinateSystem.Ymin", -20037508.3427892)
 	viper.SetDefault("CoordinateSystem.Xmax", 20037508.3427892)
 	viper.SetDefault("CoordinateSystem.Ymax", 20037508.3427892)
+
+	viper.SetDefault("HealthEndpoint", "/health")
 }
 
 func main() {
@@ -110,6 +112,7 @@ func main() {
 	flagHelpOn := getopt.BoolLong("help", 'h', "display help output")
 	flagVersionOn := getopt.BoolLong("version", 'v', "display version number")
 	flagHidePreview := getopt.BoolLong("no-preview", 'n', "hide web interface")
+	flagHealthEndpoint := getopt.StringLong("health", 'e', "", "desired path to health endpoint, e.g. \"/health\"")
 	getopt.Parse()
 
 	if *flagHelpOn {
@@ -145,6 +148,10 @@ func main() {
 		viper.Set("ShowPreview", false)
 	}
 
+	if *flagHealthEndpoint != "" {
+		viper.Set("HealthEndpoint", *flagHealthEndpoint)
+	}
+
 	// Report our status
 	log.Infof("%s %s", programName, programVersion)
 	log.Info("Run with --help parameter for commandline options")
@@ -391,6 +398,13 @@ func requestTiles(w http.ResponseWriter, r *http.Request) error {
 	return nil
 }
 
+// A simple health check endpoint
+func healthCheck(w http.ResponseWriter, r *http.Request) error {
+	w.WriteHeader(http.StatusOK)
+	w.Write([]byte("200 OK"))
+	return nil
+}
+
 /******************************************************************************/
 
 // tileAppError is an optional error structure functions can return
@@ -488,6 +502,8 @@ func tileRouter() *mux.Router {
 	if viper.GetBool("EnableMetrics") {
 		r.Handle("/metrics", promhttp.Handler())
 	}
+
+	r.Handle(viper.GetString("HealthEndpoint"), tileAppHandler(healthCheck)).Methods(http.MethodGet)
 	return r
 }
 

main_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -27,6 +28,7 @@ func TestMain(m *testing.M) {
 	sql := "CREATE EXTENSION IF NOT EXISTS postgis"
 	_, err = db.Exec(context.Background(), sql)
 	if err != nil {
+		fmt.Printf("Error creating extension: %s", err)
 		os.Exit(1)
 	}
 
@@ -67,6 +69,98 @@ func TestBasePath(t *testing.T) {
 		response := httptest.NewRecorder()
 		r.ServeHTTP(response, request)
 		assert.Equal(t, 200, response.Code, "OK response is expected")
+
+		request, _ = http.NewRequest("GET", "/test/health", nil)
+		response = httptest.NewRecorder()
+		r.ServeHTTP(response, request)
+		assert.Equal(t, 200, response.Code, "OK response is expected")
 	}
 
+	// cleanup
+	viper.Set("BasePath", "/")
+}
+
+// Test that the preview endpoints are hidden or shown according to the config
+func TestShowPreview(t *testing.T) {
+	viper.Set("ShowPreview", true)
+	r := tileRouter()
+	request, _ := http.NewRequest("GET", "/index.json", nil)
+	response := httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 200, response.Code, "OK response is expected")
+	request, _ = http.NewRequest("GET", "/index.html", nil)
+	response = httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 200, response.Code, "OK response is expected")
+}
+
+// the current default behavior is to show the preview
+func TestShowPreviewDefault(t *testing.T) {
+	r := tileRouter()
+	request, _ := http.NewRequest("GET", "/index.json", nil)
+	response := httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 200, response.Code, "OK response is expected")
+	request, _ = http.NewRequest("GET", "/index.html", nil)
+	response = httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 200, response.Code, "OK response is expected")
+}
+
+func TestHidePreview(t *testing.T) {
+	viper.Set("ShowPreview", false)
+	r := tileRouter()
+	request, _ := http.NewRequest("GET", "/index.json", nil)
+	response := httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 404, response.Code, "Not Found response is expected")
+	request, _ = http.NewRequest("GET", "/index.html", nil)
+	response = httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 404, response.Code, "Not Found response is expected")
+
+	// cleanup
+	viper.Set("ShowPreview", true)
+}
+
+// Test that the health endpoint gives a 200 if the server is running
+func TestHealth(t *testing.T) {
+	r := tileRouter()
+	request, _ := http.NewRequest("GET", "/health", nil)
+	response := httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 200, response.Code, "OK response is expected")
+	assert.Equal(t, "200 OK", string(response.Result().Status), "Response status should say ok")
+}
+
+func TestHealthCustomUrl(t *testing.T) {
+	viper.Set("HealthEndpoint", "/testHealthABC")
+	r := tileRouter()
+	request, _ := http.NewRequest("GET", "/health", nil)
+	response := httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 404, response.Code, "Not Found response is expected")
+	request, _ = http.NewRequest("GET", "/testHealthABC", nil)
+	response = httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 200, response.Code, "OK response is expected")
+	assert.Equal(t, "200 OK", string(response.Result().Status), "Response status should say ok")
+
+	// cleanup
+	viper.Set("HealthEndpoint", "/health")
+}
+
+func TestHealthCustomUrlWithBasePath(t *testing.T) {
+	viper.Set("BasePath", "/foo")
+	viper.Set("HealthEndpoint", "/bar")
+	r := tileRouter()
+	request, _ := http.NewRequest("GET", "/foo/bar", nil)
+	response := httptest.NewRecorder()
+	r.ServeHTTP(response, request)
+	assert.Equal(t, 200, response.Code, "OK response is expected")
+	assert.Equal(t, "200 OK", string(response.Result().Status), "Response status should say ok")
+
+	// cleanup
+	viper.Set("HealthEndpoint", "/health")
+	viper.Set("BasePath", "/")
 }

util_test.go

@@ -48,7 +48,7 @@ func TestMetrics(t *testing.T) {
 	viper.Set("EnableMetrics", true)
 
 	r := tileRouter()
-	request, _ := http.NewRequest("GET", "/test/metrics", nil)
+	request, _ := http.NewRequest("GET", "/metrics", nil)
 	response := httptest.NewRecorder()
 	r.ServeHTTP(response, request)
 	assert.Equal(t, 200, response.Code, "OK response is expected")