test: Add coverage for healthcheck server (#37)

cmd/launcher/main.go

@@ -40,19 +40,18 @@ func main() {
 	errorreporting.Init(cfg.Sentry)
 	defer errorreporting.Close()
 
-	srv := http.NewHealthCheckServer()
+	srv := http.NewHealthCheckServer(cfg.HealthCheckServerPort)
 	go func() {
-		logs.Infof("Starting health check server at port %d", http.GetPort())
-
 		if err := srv.ListenAndServe(); err != nil {
 			errMsg := "Health check server failed to start"
 			if opErr, ok := err.(*net.OpError); ok && opErr.Op == "listen" {
-				errMsg = fmt.Sprintf("%s: Port %d is already in use", errMsg, http.GetPort())
+				errMsg = fmt.Sprintf("%s: Port %s is already in use", errMsg, srv.Addr)
 			} else {
 				errMsg = fmt.Sprintf("%s: %s", errMsg, err)
 			}
 			logs.Error(errMsg)
 		}
+		logs.Infof("Started launcher's health check server at port %d", srv.Addr)
 	}()
 
 	cmd := &commands.LaunchCommand{}

internal/config/config.go

@@ -17,6 +17,11 @@ var configPath = "/etc/n8n-task-runners.json"
 
 var cfg Config
 
+const (
+	// EnvVarHealthCheckPort is the env var for the port for the launcher's health check server.
+	EnvVarHealthCheckPort = "N8N_LAUNCHER_HEALTCHECK_PORT"
+)
+
 // Config holds the full configuration for the launcher.
 type Config struct {
 	// LogLevel is the log level for the launcher. Default: `info`.
@@ -33,6 +38,9 @@ type Config struct {
 	// TaskBrokerURI is the URI of the task broker server.
 	TaskBrokerURI string `env:"N8N_TASK_BROKER_URI, default=http://127.0.0.1:5679"`
 
+	// HealthCheckServerPort is the port for the launcher's health check server.
+	HealthCheckServerPort string `env:"N8N_LAUNCHER_HEALTCHECK_PORT, default=5680"`
+
 	// Runner is the runner config for the task runner, obtained from:
 	// `/etc/n8n-task-runners.json`.
 	Runner *RunnerConfig
@@ -92,6 +100,10 @@ func LoadConfig(runnerType string, lookuper envconfig.Lookuper) (*Config, error)
 		cfgErrs = append(cfgErrs, errs.ErrNegativeAutoShutdownTimeout)
 	}
 
+	if port, err := strconv.Atoi(cfg.HealthCheckServerPort); err != nil || port <= 0 || port >= 65536 {
+		cfgErrs = append(cfgErrs, fmt.Errorf("%s must be a valid port number", EnvVarHealthCheckPort))
+	}
+
 	// runner
 
 	runnerCfg, err := readFileConfig(runnerType)

internal/http/healthcheck_server.go

@@ -4,26 +4,22 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
-	"os"
-	"strconv"
 	"task-runner-launcher/internal/logs"
 	"time"
 )
 
 const (
-	defaultPort     = 5680
-	portEnvVar      = "N8N_LAUNCHER_HEALTCHECK_PORT"
 	healthCheckPath = "/healthz"
 	readTimeout     = 1 * time.Second
 	writeTimeout    = 1 * time.Second
 )
 
-func NewHealthCheckServer() *http.Server {
+func NewHealthCheckServer(port string) *http.Server {
 	mux := http.NewServeMux()
 	mux.HandleFunc(healthCheckPath, handleHealthCheck)
 
 	return &http.Server{
-		Addr:         fmt.Sprintf(":%d", GetPort()),
+		Addr:         fmt.Sprintf(":%s", port),
 		Handler:      mux,
 		ReadTimeout:  readTimeout,
 		WriteTimeout: writeTimeout,
@@ -48,14 +44,3 @@ func handleHealthCheck(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 }
-
-func GetPort() int {
-	if customPortStr := os.Getenv(portEnvVar); customPortStr != "" {
-		if customPort, err := strconv.Atoi(customPortStr); err == nil && customPort > 0 && customPort < 65536 {
-			return customPort
-		}
-		logs.Warnf("%s sets an invalid port, falling back to default port %d", portEnvVar, defaultPort)
-	}
-
-	return defaultPort
-}

internal/http/healthcheck_server_test.go

@@ -0,0 +1,114 @@
+package http
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestHealthCheckHandler(t *testing.T) {
+	tests := []struct {
+		name           string
+		method         string
+		expectedStatus int
+		wantBody       bool
+	}{
+		{
+			name:           "GET request returns 200 and status ok",
+			method:         http.MethodGet,
+			expectedStatus: http.StatusOK,
+			wantBody:       true,
+		},
+		{
+			name:           "POST request returns 405 and status not allowed",
+			method:         http.MethodPost,
+			expectedStatus: http.StatusMethodNotAllowed,
+			wantBody:       false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := httptest.NewRequest(tt.method, "/healthz", nil)
+			w := httptest.NewRecorder()
+
+			handleHealthCheck(w, req)
+
+			if got := w.Code; got != tt.expectedStatus {
+				t.Errorf("handleHealthCheck() status = %v, want %v", got, tt.expectedStatus)
+			}
+
+			if tt.wantBody {
+				var response struct {
+					Status string `json:"status"`
+				}
+
+				if err := json.NewDecoder(w.Body).Decode(&response); err != nil {
+					t.Errorf("failed to decode response body: %v", err)
+				}
+
+				if response.Status != "ok" {
+					t.Errorf("handleHealthCheck() status = %v, want %v", response.Status, "ok")
+				}
+
+				if contentType := w.Header().Get("Content-Type"); contentType != "application/json" {
+					t.Errorf("handleHealthCheck() Content-Type = %v, want %v", contentType, "application/json")
+				}
+			}
+		})
+	}
+}
+
+func TestHealthCheckHandlerEncodingError(t *testing.T) {
+	req := httptest.NewRequest(http.MethodGet, "/healthz", nil)
+
+	failingWriter := &failingWriter{
+		headers: http.Header{},
+	}
+	handleHealthCheck(failingWriter, req)
+
+	if failingWriter.statusCode != http.StatusInternalServerError {
+		t.Errorf("handleHealthCheck() with encoding error, status = %v, want %v",
+			failingWriter.statusCode, http.StatusInternalServerError)
+	}
+}
+
+type failingWriter struct {
+	statusCode int
+	headers    http.Header
+}
+
+func (w *failingWriter) Header() http.Header {
+	return w.headers
+}
+
+func (w *failingWriter) Write([]byte) (int, error) {
+	return 0, fmt.Errorf("encoding error")
+}
+
+func (w *failingWriter) WriteHeader(statusCode int) {
+	w.statusCode = statusCode
+}
+
+func TestNewHealthCheckServer(t *testing.T) {
+	server := NewHealthCheckServer("5680")
+
+	if server == nil {
+		t.Fatal("NewHealthCheckServer() returned nil")
+		return
+	}
+
+	if server.Addr != ":5680" {
+		t.Errorf("NewHealthCheckServer() addr = %v, want %v", server.Addr, ":5680")
+	}
+
+	if server.ReadTimeout != readTimeout {
+		t.Errorf("NewHealthCheckServer() readTimeout = %v, want %v", server.ReadTimeout, readTimeout)
+	}
+
+	if server.WriteTimeout != writeTimeout {
+		t.Errorf("NewHealthCheckServer() writeTimeout = %v, want %v", server.WriteTimeout, writeTimeout)
+	}
+}