fix(api): wait for modules readiness before starting server (#752)

pkg/modules/chromium/chromium.go

@@ -231,7 +231,7 @@ func (mod *Chromium) Descriptor() gotenberg.ModuleDescriptor {
 
 			fs.Int64("chromium-restart-after", 0, "Number of conversions after which Chromium will automatically restart. Set to 0 to disable this feature")
 			fs.Bool("chromium-auto-start", false, "Automatically launch Chromium upon initialization if set to true; otherwise, Chromium will start at the time of the first conversion")
-			fs.Duration("chromium-start-timeout", time.Duration(10)*time.Second, "Maximum duration to wait for Chromium to start or restart")
+			fs.Duration("chromium-start-timeout", time.Duration(20)*time.Second, "Maximum duration to wait for Chromium to start or restart")
 			fs.Bool("chromium-incognito", false, "Start Chromium with incognito mode")
 			fs.Bool("chromium-allow-insecure-localhost", false, "Ignore TLS/SSL errors on localhost")
 			fs.Bool("chromium-ignore-certificate-errors", false, "Ignore the certificate errors")
@@ -408,6 +408,34 @@ func (mod *Chromium) Checks() ([]health.CheckerOption, error) {
 	}, nil
 }
 
+// Ready returns no error if the module is ready.
+func (mod *Chromium) Ready() error {
+	if !mod.autoStart {
+		return nil
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), mod.args.wsUrlReadTimeout)
+	defer cancel()
+
+	ticker := time.NewTicker(time.Duration(100) * time.Millisecond)
+
+	for {
+		select {
+		case <-ctx.Done():
+			ticker.Stop()
+			return fmt.Errorf("context done while waiting for Chromium to be ready: %w", ctx.Err())
+		case <-ticker.C:
+			ok := mod.browser.Healthy(mod.logger)
+			if ok {
+				ticker.Stop()
+				return nil
+			}
+
+			continue
+		}
+	}
+}
+
 // Chromium returns an [Api] for interacting with Chromium for converting HTML
 // documents to PDF.
 func (mod *Chromium) Chromium() (Api, error) {

pkg/modules/chromium/chromium_test.go

@@ -399,6 +399,61 @@ func TestChromium_Checks(t *testing.T) {
 	}
 }
 
+func TestChromium_Ready(t *testing.T) {
+	for _, tc := range []struct {
+		scenario     string
+		autoStart    bool
+		startTimeout time.Duration
+		browser      browser
+		expectError  bool
+	}{
+		{
+			scenario:     "no auto-start",
+			autoStart:    false,
+			startTimeout: time.Duration(30) * time.Second,
+			browser: &browserMock{ProcessMock: gotenberg.ProcessMock{HealthyMock: func(logger *zap.Logger) bool {
+				return false
+			}}},
+			expectError: false,
+		},
+		{
+			scenario:     "auto-start: context done",
+			autoStart:    true,
+			startTimeout: time.Duration(200) * time.Millisecond,
+			browser: &browserMock{ProcessMock: gotenberg.ProcessMock{HealthyMock: func(logger *zap.Logger) bool {
+				return false
+			}}},
+			expectError: true,
+		},
+		{
+			scenario:     "auto-start success",
+			autoStart:    true,
+			startTimeout: time.Duration(30) * time.Second,
+			browser: &browserMock{ProcessMock: gotenberg.ProcessMock{HealthyMock: func(logger *zap.Logger) bool {
+				return true
+			}}},
+			expectError: false,
+		},
+	} {
+		t.Run(tc.scenario, func(t *testing.T) {
+			mod := new(Chromium)
+			mod.autoStart = tc.autoStart
+			mod.args = browserArguments{wsUrlReadTimeout: tc.startTimeout}
+			mod.browser = tc.browser
+
+			err := mod.Ready()
+
+			if !tc.expectError && err != nil {
+				t.Fatalf("expected no error but got: %v", err)
+			}
+
+			if tc.expectError && err == nil {
+				t.Fatal("expected error but got none")
+			}
+		})
+	}
+}
+
 func TestChromium_Chromium(t *testing.T) {
 	mod := new(Chromium)
 

pkg/modules/chromium/events.go

@@ -179,7 +179,6 @@ func waitForEventLoadingFinished(ctx context.Context, logger *zap.Logger) func()
 // completed or an error is encountered.
 func runBatch(ctx context.Context, fn ...func() error) error {
 	eg, _ := errgroup.WithContext(ctx)
-
 	for _, f := range fn {
 		eg.Go(f)
 	}

pkg/modules/chromium/tasks.go

@@ -295,12 +295,11 @@ func waitForExpressionBeforePrintActionFunc(logger *zap.Logger, disableJavaScrip
 			select {
 			case <-ctx.Done():
 				ticker.Stop()
-
 				return fmt.Errorf("context done while evaluating '%s': %w", expression, ctx.Err())
 			case <-ticker.C:
 				var ok bool
-
 				evaluate := chromedp.Evaluate(expression, &ok)
+
 				err := evaluate.Do(ctx)
 				if err != nil {
 					return fmt.Errorf("evaluate: %v: %w", err, ErrInvalidEvaluationExpression)
@@ -308,7 +307,6 @@ func waitForExpressionBeforePrintActionFunc(logger *zap.Logger, disableJavaScrip
 
 				if ok {
 					ticker.Stop()
-
 					return nil
 				}