[Gateway] Simple healthcheck endpoint (#10786)

core/services/gateway/network/httpserver.go

@@ -54,6 +54,11 @@ type httpServer struct {
 	lggr              logger.Logger
 }
 
+const (
+	HealthCheckPath     = "/health"
+	HealthCheckResponse = "OK"
+)
+
 func NewHttpServer(config *HTTPServerConfig, lggr logger.Logger) HttpServer {
 	baseCtx, cancelBaseCtx := context.WithCancel(context.Background())
 	server := &httpServer{
@@ -64,6 +69,7 @@ func NewHttpServer(config *HTTPServerConfig, lggr logger.Logger) HttpServer {
 	}
 	mux := http.NewServeMux()
 	mux.Handle(config.Path, http.HandlerFunc(server.handleRequest))
+	mux.Handle(HealthCheckPath, http.HandlerFunc(server.handleHealthCheck))
 	server.server = &http.Server{
 		Addr:              fmt.Sprintf("%s:%d", config.Host, config.Port),
 		Handler:           mux,
@@ -75,6 +81,14 @@ func NewHttpServer(config *HTTPServerConfig, lggr logger.Logger) HttpServer {
 	return server
 }
 
+func (s *httpServer) handleHealthCheck(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	_, err := w.Write([]byte(HealthCheckResponse))
+	if err != nil {
+		s.lggr.Debug("error when writing response for healthcheck", err)
+	}
+}
+
 func (s *httpServer) handleRequest(w http.ResponseWriter, r *http.Request) {
 	source := http.MaxBytesReader(nil, r.Body, s.config.MaxRequestBytes)
 	rawMessage, err := io.ReadAll(source)

core/services/gateway/network/httpserver_test.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/mock"
@@ -74,3 +75,15 @@ func TestHTTPServer_HandleRequest_RequestBodyTooBig(t *testing.T) {
 	resp := sendRequest(t, url, []byte("0123456789"))
 	require.Equal(t, http.StatusBadRequest, resp.StatusCode)
 }
+
+func TestHTTPServer_HandleHealthCheck(t *testing.T) {
+	server, _, url := startNewServer(t, 100_000, 100_000)
+	defer server.Close()
+
+	url = strings.Replace(url, HTTPTestPath, network.HealthCheckPath, 1)
+	resp := sendRequest(t, url, []byte{})
+	respBytes, err := io.ReadAll(resp.Body)
+	require.NoError(t, err)
+	require.Equal(t, http.StatusOK, resp.StatusCode)
+	require.Equal(t, []byte(network.HealthCheckResponse), respBytes)
+}