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

Makefile

@@ -29,13 +29,14 @@ build: ## Build the Gotenberg's Docker image
 GOTENBERG_GRACEFUL_SHUTDOWN_DURATION=30s
 API_PORT=3000
 API_PORT_FROM_ENV=
+API_START_TIMEOUT=30s
 API_TIMEOUT=30s
 API_ROOT_PATH=/
 API_TRACE_HEADER=Gotenberg-Trace
 API_DISABLE_HEALTH_CHECK_LOGGING=false
 CHROMIUM_RESTART_AFTER=0
 CHROMIUM_AUTO_START=false
-CHROMIUM_START_TIMEOUT=10s
+CHROMIUM_START_TIMEOUT=20s
 CHROMIUM_INCOGNITO=false
 CHROMIUM_ALLOW_INSECURE_LOCALHOST=false
 CHROMIUM_IGNORE_CERTIFICATE_ERRORS=false
@@ -49,7 +50,7 @@ CHROMIUM_DISABLE_JAVASCRIPT=false
 CHROMIUM_DISABLE_ROUTES=false
 LIBREOFFICE_RESTART_AFTER=10
 LIBREOFFICE_AUTO_START=false
-LIBREOFFICE_START_TIMEOUT=10s
+LIBREOFFICE_START_TIMEOUT=20s
 LIBREOFFICE_DISABLE_ROUTES=false
 LOG_LEVEL=info
 LOG_FORMAT=auto
@@ -79,6 +80,7 @@ run: ## Start a Gotenberg container
 	--gotenberg-graceful-shutdown-duration=$(GOTENBERG_GRACEFUL_SHUTDOWN_DURATION) \
 	--api-port=$(API_PORT) \
 	--api-port-from-env=$(API_PORT_FROM_ENV) \
+	--api-start-timeout=$(API_START_TIMEOUT) \
 	--api-timeout=$(API_TIMEOUT) \
 	--api-root-path=$(API_ROOT_PATH) \
 	--api-trace-header=$(API_TRACE_HEADER) \

cmd/gotenberg.go

@@ -84,7 +84,6 @@ func Run() {
 			startupMessage := app.StartupMessage()
 			if startupMessage == "" {
 				fmt.Printf("[SYSTEM] %s: application started\n", id)
-
 				return
 			}
 
@@ -144,7 +143,6 @@ func Run() {
 				}
 
 				fmt.Printf("[SYSTEM] %s: application stopped\n", id)
-
 				return nil
 			}
 		}(a.(gotenberg.App)))

go.mod

@@ -8,7 +8,7 @@ require (
 	github.com/chromedp/cdproto v0.0.0-20231205062650-00455a960d61
 	github.com/chromedp/chromedp v0.9.3
 	github.com/golang/snappy v0.0.4 // indirect
-	github.com/google/uuid v1.4.0
+	github.com/google/uuid v1.5.0
 	github.com/hashicorp/go-cleanhttp v0.5.2 // indirect
 	github.com/hashicorp/go-retryablehttp v0.7.5
 	github.com/klauspost/compress v1.17.4 // indirect

go.sum

@@ -35,8 +35,8 @@ github.com/golang/snappy v0.0.4/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEW
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
-github.com/google/uuid v1.4.0 h1:MtMxsa51/r9yyhkyLsVeVt0B+BGQZzpQiTQ4eHZ8bc4=
+github.com/google/uuid v1.5.0 h1:1p67kYwdtXjb0gL0BPiP1Av9wiZPo5A8z2cWkTZ+eyU=
-github.com/google/uuid v1.4.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/google/uuid v1.5.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/css v1.0.1 h1:ntNaBIghp6JmvWnxbZKANoLyuXTPZ4cAMlo6RyhlbO8=
 github.com/gorilla/css v1.0.1/go.mod h1:BvnYkspnSzMmwRK+b8/xgNPLiIuNZr6vbZBTPQ2A3b0=
 github.com/hashicorp/go-cleanhttp v0.5.2 h1:035FKYIWjmULyFRBKPs8TBQoi0x6d9G4xc9neXJWAZQ=

pkg/modules/api/api.go

@@ -17,6 +17,7 @@ import (
 	"go.uber.org/multierr"
 	"go.uber.org/zap"
 	"golang.org/x/net/http2"
+	"golang.org/x/sync/errgroup"
 
 	"github.com/gotenberg/gotenberg/v7/pkg/gotenberg"
 )
@@ -29,6 +30,7 @@ func init() {
 // middlewares or health checks.
 type Api struct {
 	port                      int
+	startTimeout              time.Duration
 	timeout                   time.Duration
 	rootPath                  string
 	traceHeader               string
@@ -37,6 +39,7 @@ type Api struct {
 	routes              []Route
 	externalMiddlewares []Middleware
 	healthChecks        []health.CheckerOption
+	readyFn             []func() error
 	fs                  *gotenberg.FileSystem
 	logger              *zap.Logger
 	srv                 *echo.Echo
@@ -145,6 +148,7 @@ type Middleware struct {
 // See https://github.com/alexliesenfeld/health for more details.
 type HealthChecker interface {
 	Checks() ([]health.CheckerOption, error)
+	Ready() error
 }
 
 // Descriptor returns an [Api]'s module descriptor.
@@ -155,6 +159,7 @@ func (a *Api) Descriptor() gotenberg.ModuleDescriptor {
 			fs := flag.NewFlagSet("api", flag.ExitOnError)
 			fs.Int("api-port", 3000, "Set the port on which the API should listen")
 			fs.String("api-port-from-env", "", "Set the environment variable with the port on which the API should listen - override the default port")
+			fs.Duration("api-start-timeout", time.Duration(30)*time.Second, "Set the time limit for the API to start")
 			fs.Duration("api-timeout", time.Duration(30)*time.Second, "Set the time limit for requests")
 			fs.String("api-root-path", "/", "Set the root path of the API - for service discovery via URL paths")
 			fs.String("api-trace-header", "Gotenberg-Trace", "Set the header name to use for identifying requests")
@@ -170,6 +175,7 @@ func (a *Api) Descriptor() gotenberg.ModuleDescriptor {
 func (a *Api) Provision(ctx *gotenberg.Context) error {
 	flags := ctx.ParsedFlags()
 	a.port = flags.MustInt("api-port")
+	a.startTimeout = flags.MustDuration("api-start-timeout")
 	a.timeout = flags.MustDuration("api-timeout")
 	a.rootPath = flags.MustString("api-root-path")
 	a.traceHeader = flags.MustString("api-trace-header")
@@ -259,6 +265,7 @@ func (a *Api) Provision(ctx *gotenberg.Context) error {
 		}
 
 		a.healthChecks = append(a.healthChecks, checks...)
+		a.readyFn = append(a.readyFn, healthChecker.Ready)
 	}
 
 	// Logger.
@@ -430,12 +437,25 @@ func (a *Api) Start() error {
 		func() echo.HandlerFunc {
 			checks := append(a.healthChecks, health.WithTimeout(a.timeout))
 			checker := health.NewChecker(checks...)
-
 			return echo.WrapHandler(health.NewHandler(checker))
 		}(),
 		hardTimeoutMiddleware(hardTimeout),
 	)
 
+	// Wait for all modules to be ready.
+	ctx, cancel := context.WithTimeout(context.Background(), a.startTimeout)
+	defer cancel()
+
+	eg, _ := errgroup.WithContext(ctx)
+	for _, f := range a.readyFn {
+		eg.Go(f)
+	}
+
+	err := eg.Wait()
+	if err != nil {
+		return fmt.Errorf("waiting for modules readiness: %w", err)
+	}
+
 	// As the following code is blocking, run it in a goroutine.
 	go func() {
 		server := &http2.Server{}

pkg/modules/api/api_test.go

@@ -10,6 +10,7 @@ import (
 	"os"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/alexliesenfeld/health"
 	"github.com/labstack/echo/v4"
@@ -222,9 +223,6 @@ func TestApi_Provision(t *testing.T) {
 				mod.ValidateMock = func() error {
 					return errors.New("foo")
 				}
-				mod.ChecksMock = func() ([]health.CheckerOption, error) {
-					return nil, nil
-				}
 				return gotenberg.NewContext(
 					gotenberg.ParsedFlags{
 						FlagSet: new(Api).Descriptor().FlagSet,
@@ -347,6 +345,9 @@ func TestApi_Provision(t *testing.T) {
 				mod3.ChecksMock = func() ([]health.CheckerOption, error) {
 					return []health.CheckerOption{health.WithDisabledAutostart()}, nil
 				}
+				mod3.ReadyMock = func() error {
+					return nil
+				}
 
 				mod4 := &struct {
 					gotenberg.ModuleMock
@@ -643,141 +644,176 @@ func TestApi_Validate(t *testing.T) {
 }
 
 func TestApi_Start(t *testing.T) {
-	mod := new(Api)
+	for _, tc := range []struct {
-	mod.port = 3000
+		scenario    string
-	mod.rootPath = "/"
+		readyFn     []func() error
-	mod.disableHealthCheckLogging = true
+		expectError bool
-	mod.routes = []Route{
+	}{
 		{
-			Method:         http.MethodPost,
+			scenario: "at least one module not ready",
-			Path:           "/forms/foo",
+			readyFn: []func() error{
-			IsMultipart:    true,
+				func() error { return nil },
-			DisableLogging: true,
+				func() error { return errors.New("not ready") },
-			Handler: func(c echo.Context) error {
-				ctx := c.Get("context").(*Context)
-				ctx.outputPaths = []string{
-					"/tests/test/testdata/api/sample1.txt",
-				}
-
-				return nil
 			},
+			expectError: true,
 		},
 		{
-			Method:      http.MethodPost,
+			scenario: "success",
-			Path:        "/forms/bar",
+			readyFn: []func() error{
-			IsMultipart: true,
+				func() error { return nil },
-			Handler:     func(_ echo.Context) error { return errors.New("foo") },
+				func() error { return nil },
+			},
+			expectError: false,
 		},
-	}
+	} {
-	mod.externalMiddlewares = []Middleware{
+		t.Run(tc.scenario, func(t *testing.T) {
-		{
+			mod := new(Api)
-			Stack: PreRouterStack,
+			mod.port = 3000
-			Handler: func() echo.MiddlewareFunc {
+			mod.startTimeout = time.Duration(30) * time.Second
-				return func(next echo.HandlerFunc) echo.HandlerFunc {
+			mod.rootPath = "/"
-					return func(c echo.Context) error {
+			mod.disableHealthCheckLogging = true
-						return next(c)
+			mod.routes = []Route{
-					}
+				{
-				}
+					Method:         http.MethodPost,
-			}(),
+					Path:           "/forms/foo",
-		},
+					IsMultipart:    true,
-		{
+					DisableLogging: true,
-			Stack: MultipartStack,
+					Handler: func(c echo.Context) error {
-			Handler: func() echo.MiddlewareFunc {
+						ctx := c.Get("context").(*Context)
-				return func(next echo.HandlerFunc) echo.HandlerFunc {
+						ctx.outputPaths = []string{
-					return func(c echo.Context) error {
+							"/tests/test/testdata/api/sample1.txt",
-						return next(c)
+						}
-					}
-				}
-			}(),
-		},
-		{
-			Stack: DefaultStack,
-			Handler: func() echo.MiddlewareFunc {
-				return func(next echo.HandlerFunc) echo.HandlerFunc {
-					return func(c echo.Context) error {
-						return next(c)
-					}
-				}
-			}(),
-		},
-		{
-			Handler: func() echo.MiddlewareFunc {
-				return func(next echo.HandlerFunc) echo.HandlerFunc {
-					return func(c echo.Context) error {
-						return next(c)
-					}
-				}
-			}(),
-		},
-	}
-	mod.fs = gotenberg.NewFileSystem()
-	mod.logger = zap.NewNop()
 
-	err := mod.Start()
+						return nil
-	if err != nil {
+					},
-		t.Fatalf("expected no error but got: %v", err)
+				},
-	}
+				{
+					Method:      http.MethodPost,
+					Path:        "/forms/bar",
+					IsMultipart: true,
+					Handler:     func(_ echo.Context) error { return errors.New("foo") },
+				},
+			}
+			mod.externalMiddlewares = []Middleware{
+				{
+					Stack: PreRouterStack,
+					Handler: func() echo.MiddlewareFunc {
+						return func(next echo.HandlerFunc) echo.HandlerFunc {
+							return func(c echo.Context) error {
+								return next(c)
+							}
+						}
+					}(),
+				},
+				{
+					Stack: MultipartStack,
+					Handler: func() echo.MiddlewareFunc {
+						return func(next echo.HandlerFunc) echo.HandlerFunc {
+							return func(c echo.Context) error {
+								return next(c)
+							}
+						}
+					}(),
+				},
+				{
+					Stack: DefaultStack,
+					Handler: func() echo.MiddlewareFunc {
+						return func(next echo.HandlerFunc) echo.HandlerFunc {
+							return func(c echo.Context) error {
+								return next(c)
+							}
+						}
+					}(),
+				},
+				{
+					Handler: func() echo.MiddlewareFunc {
+						return func(next echo.HandlerFunc) echo.HandlerFunc {
+							return func(c echo.Context) error {
+								return next(c)
+							}
+						}
+					}(),
+				},
+			}
+			mod.readyFn = tc.readyFn
+			mod.fs = gotenberg.NewFileSystem()
+			mod.logger = zap.NewNop()
 
-	// health request.
+			err := mod.Start()
-	recorder := httptest.NewRecorder()
+			if !tc.expectError && err != nil {
-	healthRequest := httptest.NewRequest(http.MethodGet, "/health", nil)
-
-	mod.srv.ServeHTTP(recorder, healthRequest)
-	if recorder.Code != http.StatusOK {
-		t.Errorf("expected %d status code but got %d", http.StatusOK, recorder.Code)
-	}
-
-	// "multipart/form-data" request.
-	multipartRequest := func(url string) *http.Request {
-		body := &bytes.Buffer{}
-
-		writer := multipart.NewWriter(body)
-
-		defer func() {
-			err := writer.Close()
-			if err != nil {
 				t.Fatalf("expected no error but got: %v", err)
 			}
-		}()
 
-		err := writer.WriteField("foo", "foo")
+			if tc.expectError && err == nil {
-		if err != nil {
+				t.Fatal("expected error but got none")
-			t.Fatalf("expected no error but got: %v", err)
+			}
-		}
 
-		part, err := writer.CreateFormFile("foo.txt", "foo.txt")
+			if tc.expectError {
-		if err != nil {
+				return
-			t.Fatalf("expected no error but got: %v", err)
+			}
-		}
 
-		_, err = part.Write([]byte("foo"))
+			// health request.
-		if err != nil {
+			recorder := httptest.NewRecorder()
-			t.Fatalf("expected no error but got: %v", err)
+			healthRequest := httptest.NewRequest(http.MethodGet, "/health", nil)
-		}
 
-		req := httptest.NewRequest(http.MethodPost, url, body)
+			mod.srv.ServeHTTP(recorder, healthRequest)
-		req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+			if recorder.Code != http.StatusOK {
+				t.Errorf("expected %d status code but got %d", http.StatusOK, recorder.Code)
+			}
 
-		return req
+			// "multipart/form-data" request.
-	}
+			multipartRequest := func(url string) *http.Request {
+				body := &bytes.Buffer{}
 
-	recorder = httptest.NewRecorder()
+				writer := multipart.NewWriter(body)
-	mod.srv.ServeHTTP(recorder, multipartRequest("/forms/foo"))
 
-	if recorder.Code != http.StatusOK {
+				defer func() {
-		t.Errorf("expected %d status code but got %d", http.StatusOK, recorder.Code)
+					err := writer.Close()
-	}
+					if err != nil {
+						t.Fatalf("expected no error but got: %v", err)
+					}
+				}()
 
-	recorder = httptest.NewRecorder()
+				err := writer.WriteField("foo", "foo")
-	mod.srv.ServeHTTP(recorder, multipartRequest("/forms/bar"))
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
 
-	if recorder.Code != http.StatusInternalServerError {
+				part, err := writer.CreateFormFile("foo.txt", "foo.txt")
-		t.Errorf("expected %d status code but got %d", http.StatusInternalServerError, recorder.Code)
+				if err != nil {
-	}
+					t.Fatalf("expected no error but got: %v", err)
+				}
 
-	err = mod.srv.Shutdown(context.TODO())
+				_, err = part.Write([]byte("foo"))
-	if err != nil {
+				if err != nil {
-		t.Errorf("expected no error but got: %v", err)
+					t.Fatalf("expected no error but got: %v", err)
+				}
+
+				req := httptest.NewRequest(http.MethodPost, url, body)
+				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+
+				return req
+			}
+
+			recorder = httptest.NewRecorder()
+			mod.srv.ServeHTTP(recorder, multipartRequest("/forms/foo"))
+
+			if recorder.Code != http.StatusOK {
+				t.Errorf("expected %d status code but got %d", http.StatusOK, recorder.Code)
+			}
+
+			recorder = httptest.NewRecorder()
+			mod.srv.ServeHTTP(recorder, multipartRequest("/forms/bar"))
+
+			if recorder.Code != http.StatusInternalServerError {
+				t.Errorf("expected %d status code but got %d", http.StatusInternalServerError, recorder.Code)
+			}
+
+			err = mod.srv.Shutdown(context.TODO())
+			if err != nil {
+				t.Errorf("expected no error but got: %v", err)
+			}
+		})
 	}
 }
 

pkg/modules/api/mocks.go

@@ -105,12 +105,17 @@ func (provider *MiddlewareProviderMock) Middlewares() ([]Middleware, error) {
 // HealthCheckerMock is mock for the [HealthChecker] interface.
 type HealthCheckerMock struct {
 	ChecksMock func() ([]health.CheckerOption, error)
+	ReadyMock  func() error
 }
 
 func (mod *HealthCheckerMock) Checks() ([]health.CheckerOption, error) {
 	return mod.ChecksMock()
 }
 
+func (mod *HealthCheckerMock) Ready() error {
+	return mod.ReadyMock()
+}
+
 // Interface guards.
 var (
 	_ Router             = (*RouterMock)(nil)

pkg/modules/api/mocks_test.go

@@ -148,10 +148,18 @@ func TestHealthCheckerMock(t *testing.T) {
 		ChecksMock: func() ([]health.CheckerOption, error) {
 			return nil, nil
 		},
+		ReadyMock: func() error {
+			return nil
+		},
 	}
 
 	_, err := mock.Checks()
 	if err != nil {
 		t.Errorf("expected no error from HealthCheckerMock.Checks, but got: %v", err)
 	}
+
+	err = mock.Ready()
+	if err != nil {
+		t.Errorf("expected no error from HealthCheckerMock.Ready, but got: %v", err)
+	}
 }

pkg/modules/chromium/chromium.go

@@ -226,7 +226,7 @@ func (mod *Chromium) Descriptor() gotenberg.ModuleDescriptor {
 			fs := flag.NewFlagSet("chromium", flag.ExitOnError)
 			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")
@@ -387,6 +387,34 @@ 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

@@ -389,6 +389,61 @@ 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

@@ -304,12 +304,11 @@ 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)
@@ -317,7 +316,6 @@ func waitForExpressionBeforePrintActionFunc(logger *zap.Logger, disableJavaScrip
 
 				if ok {
 					ticker.Stop()
-
 					return nil
 				}
 

pkg/modules/libreoffice/api/api.go

@@ -81,7 +81,7 @@ func (a *Api) Descriptor() gotenberg.ModuleDescriptor {
 			fs := flag.NewFlagSet("api", flag.ExitOnError)
 			fs.Int64("libreoffice-restart-after", 10, "Number of conversions after which LibreOffice will automatically restart. Set to 0 to disable this feature")
 			fs.Bool("libreoffice-auto-start", false, "Automatically launch LibreOffice upon initialization if set to true; otherwise, LibreOffice will start at the time of the first conversion")
-			fs.Duration("libreoffice-start-timeout", time.Duration(10)*time.Second, "Maximum duration to wait for LibreOffice to start or restart")
+			fs.Duration("libreoffice-start-timeout", time.Duration(20)*time.Second, "Maximum duration to wait for LibreOffice to start or restart")
 
 			return fs
 		}(),
@@ -221,6 +221,34 @@ func (a *Api) Checks() ([]health.CheckerOption, error) {
 	}, nil
 }
 
+// Ready returns no error if the module is ready.
+func (a *Api) Ready() error {
+	if !a.autoStart {
+		return nil
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), a.args.startTimeout)
+	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 LibreOffice to be ready: %w", ctx.Err())
+		case <-ticker.C:
+			ok := a.libreOffice.Healthy(a.logger)
+			if ok {
+				ticker.Stop()
+				return nil
+			}
+
+			continue
+		}
+	}
+}
+
 // LibreOffice returns a [Uno] for interacting with LibreOffice.
 func (a *Api) LibreOffice() (Uno, error) {
 	return a, nil

pkg/modules/libreoffice/api/api_test.go

@@ -339,6 +339,61 @@ func TestApi_Checks(t *testing.T) {
 	}
 }
 
+func TestChromium_Ready(t *testing.T) {
+	for _, tc := range []struct {
+		scenario     string
+		autoStart    bool
+		startTimeout time.Duration
+		libreOffice  libreOffice
+		expectError  bool
+	}{
+		{
+			scenario:     "no auto-start",
+			autoStart:    false,
+			startTimeout: time.Duration(30) * time.Second,
+			libreOffice: &libreOfficeMock{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,
+			libreOffice: &libreOfficeMock{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,
+			libreOffice: &libreOfficeMock{ProcessMock: gotenberg.ProcessMock{HealthyMock: func(logger *zap.Logger) bool {
+				return true
+			}}},
+			expectError: false,
+		},
+	} {
+		t.Run(tc.scenario, func(t *testing.T) {
+			a := new(Api)
+			a.autoStart = tc.autoStart
+			a.args = libreOfficeArguments{startTimeout: tc.startTimeout}
+			a.libreOffice = tc.libreOffice
+
+			err := a.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 TestApi_LibreOffice(t *testing.T) {
 	a := new(Api)
 

pkg/modules/libreoffice/pdfengine/pdfengine.go

@@ -18,7 +18,7 @@ func init() {
 // LibreOfficePdfEngine interacts with the LibreOffice (Universal Network Objects) API
 // and implements the [gotenberg.PdfEngine] interface.
 type LibreOfficePdfEngine struct {
-	unoAPI api.Uno
+	unoApi api.Uno
 }
 
 // Descriptor returns a [LibreOfficePdfEngine]'s module descriptor.
@@ -36,12 +36,12 @@ func (engine *LibreOfficePdfEngine) Provision(ctx *gotenberg.Context) error {
 		return fmt.Errorf("get LibreOffice Uno provider: %w", err)
 	}
 
-	unoAPI, err := provider.(api.Provider).LibreOffice()
+	unoApi, err := provider.(api.Provider).LibreOffice()
 	if err != nil {
 		return fmt.Errorf("get LibreOffice Uno: %w", err)
 	}
 
-	engine.unoAPI = unoAPI
+	engine.unoApi = unoApi
 
 	return nil
 }
@@ -56,7 +56,7 @@ func (engine *LibreOfficePdfEngine) Merge(ctx context.Context, logger *zap.Logge
 // PDF format is requested, it returns a [gotenberg.ErrPdfFormatNotSupported]
 // error.
 func (engine *LibreOfficePdfEngine) Convert(ctx context.Context, logger *zap.Logger, formats gotenberg.PdfFormats, inputPath, outputPath string) error {
-	err := engine.unoAPI.Pdf(ctx, logger, inputPath, outputPath, api.Options{
+	err := engine.unoApi.Pdf(ctx, logger, inputPath, outputPath, api.Options{
 		PdfFormats: formats,
 	})
 

pkg/modules/libreoffice/pdfengine/pdfengine_test.go

@@ -153,7 +153,7 @@ func TestLibreOfficePdfEngine_Convert(t *testing.T) {
 		},
 	} {
 		t.Run(tc.scenario, func(t *testing.T) {
-			engine := &LibreOfficePdfEngine{unoAPI: tc.api}
+			engine := &LibreOfficePdfEngine{unoApi: tc.api}
 			err := engine.Convert(context.Background(), zap.NewNop(), gotenberg.PdfFormats{}, "", "")
 
 			if !tc.expectError && err != nil {