feat(api): add 'downloadForm' form field

Makefile

@@ -37,6 +37,10 @@ API_TRACE_HEADER=Gotenberg-Trace
 API_ENABLE_BASIC_AUTH=false
 GOTENBERG_API_BASIC_AUTH_USERNAME=
 GOTENBERG_API_BASIC_AUTH_PASSWORD=
+API-DOWNLOAD-FROM-ALLOW-LIST=
+API-DOWNLOAD-FROM-DENY-LIST=
+API-DOWNLOAD-FROM-FROM-MAX-RETRY=4
+API-DISABLE-DOWNLOAD-FROM=false
 API_DISABLE_HEALTH_CHECK_LOGGING=false
 CHROMIUM_RESTART_AFTER=0
 CHROMIUM_MAX_QUEUE_SIZE=0
@@ -95,6 +99,10 @@ run: ## Start a Gotenberg container
 	--api-root-path=$(API_ROOT_PATH) \
 	--api-trace-header=$(API_TRACE_HEADER) \
 	--api-enable-basic-auth=$(API_ENABLE_BASIC_AUTH) \
+	--api-download-from-allow-list=$(API-DOWNLOAD-FROM-ALLOW-LIST) \
+    --api-download-from-deny-list=$(API-DOWNLOAD-FROM-DENY-LIST) \
+    --api-download-from-max-retry=$(API-DOWNLOAD-FROM-FROM-MAX-RETRY) \
+    --api-disable-download-from=$(API-DISABLE-DOWNLOAD-FROM) \
 	--api-disable-health-check-logging=$(API_DISABLE_HEALTH_CHECK_LOGGING) \
 	--chromium-restart-after=$(CHROMIUM_RESTART_AFTER) \
 	--chromium-auto-start=$(CHROMIUM_AUTO_START) \
@@ -151,7 +159,7 @@ build-tests: ## Build the tests' Docker image
 tests: ## Start the testing environment
 	docker run --rm -it \
 	-v $(PWD):/tests \
-	$(DOCKER_REGISTRY)/$(DOCKER_REPOSITORY)g:$(GOTENBERG_VERSION)-tests \
+	$(DOCKER_REGISTRY)/$(DOCKER_REPOSITORY):$(GOTENBERG_VERSION)-tests \
 	bash
 
 .PHONY: tests-once

pkg/gotenberg/logging.go

@@ -1,6 +1,11 @@
 package gotenberg
 
-import "go.uber.org/zap"
+import (
+	"fmt"
+
+	"github.com/hashicorp/go-retryablehttp"
+	"go.uber.org/zap"
+)
 
 // LoggerProvider is an interface for a module that supplies a method for
 // creating a [zap.Logger] instance for use by other modules.
@@ -12,3 +17,41 @@ import "go.uber.org/zap"
 type LoggerProvider interface {
 	Logger(mod Module) (*zap.Logger, error)
 }
+
+// LeveledLogger is wrapper around a [zap.Logger] so that it may be used by a
+// [retryablehttp.Client].
+type LeveledLogger struct {
+	logger *zap.Logger
+}
+
+// NewLeveledLogger instantiates a [LeveledLogger].
+func NewLeveledLogger(logger *zap.Logger) *LeveledLogger {
+	return &LeveledLogger{
+		logger: logger,
+	}
+}
+
+// Error logs a message at error level using the wrapped zap.Logger.
+func (leveled LeveledLogger) Error(msg string, keysAndValues ...interface{}) {
+	leveled.logger.Error(fmt.Sprintf("%s: %+v", msg, keysAndValues))
+}
+
+// Warn logs a message at warning level using the wrapped zap.Logger.
+func (leveled LeveledLogger) Warn(msg string, keysAndValues ...interface{}) {
+	leveled.logger.Warn(fmt.Sprintf("%s: %+v", msg, keysAndValues))
+}
+
+// Info logs a message at info level using the wrapped zap.Logger.
+func (leveled LeveledLogger) Info(msg string, keysAndValues ...interface{}) {
+	leveled.logger.Info(fmt.Sprintf("%s: %+v", msg, keysAndValues))
+}
+
+// Debug logs a message at debug level using the wrapped zap.Logger.
+func (leveled LeveledLogger) Debug(msg string, keysAndValues ...interface{}) {
+	leveled.logger.Debug(fmt.Sprintf("%s: %+v", msg, keysAndValues))
+}
+
+// Interface guards.
+var (
+	_ retryablehttp.LeveledLogger = (*LeveledLogger)(nil)
+)

pkg/gotenberg/logging_test.go

@@ -1,4 +1,4 @@
-package webhook
+package gotenberg
 
 import (
 	"testing"
@@ -7,17 +7,17 @@ import (
 )
 
 func TestLeveledLogger_Error(t *testing.T) {
-	leveledLogger{logger: zap.NewNop()}.Error("foo")
+	NewLeveledLogger(zap.NewNop()).Error("foo")
 }
 
 func TestLeveledLogger_Warn(t *testing.T) {
-	leveledLogger{logger: zap.NewNop()}.Warn("foo")
+	NewLeveledLogger(zap.NewNop()).Warn("foo")
 }
 
 func TestLeveledLogger_Info(t *testing.T) {
-	leveledLogger{logger: zap.NewNop()}.Info("foo")
+	NewLeveledLogger(zap.NewNop()).Info("foo")
 }
 
 func TestLeveledLogger_Debug(t *testing.T) {
-	leveledLogger{logger: zap.NewNop()}.Debug("foo")
+	NewLeveledLogger(zap.NewNop()).Debug("foo")
 }

pkg/modules/api/api.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/alexliesenfeld/health"
+	"github.com/dlclark/regexp2"
 	"github.com/labstack/echo/v4"
 	flag "github.com/spf13/pflag"
 	"go.uber.org/multierr"
@@ -36,6 +37,7 @@ type Api struct {
 	traceHeader               string
 	basicAuthUsername         string
 	basicAuthPassword         string
+	downloadFromCfg           downloadFromConfig
 	disableHealthCheckLogging bool
 
 	routes              []Route
@@ -47,6 +49,13 @@ type Api struct {
 	srv                 *echo.Echo
 }
 
+type downloadFromConfig struct {
+	allowList *regexp2.Regexp
+	denyList  *regexp2.Regexp
+	maxRetry  int
+	disable   bool
+}
+
 // Router is a module interface which adds routes to the [Api].
 type Router interface {
 	Routes() ([]Route, error)
@@ -168,6 +177,10 @@ func (a *Api) Descriptor() gotenberg.ModuleDescriptor {
 			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")
 			fs.Bool("api-enable-basic-auth", false, "Enable basic authentication - will look for the GOTENBERG_API_BASIC_AUTH_USERNAME and GOTENBERG_API_BASIC_AUTH_PASSWORD environment variables")
+			fs.String("api-download-from-allow-list", "", "Set the allowed URLs for the download from feature using a regular expression")
+			fs.String("api-download-from-deny-list", "", "Set the denied URLs for the download from feature using a regular expression")
+			fs.Int("api-download-from-max-retry", 4, "Set the maximum number of retries for the download from feature")
+			fs.Bool("api-disable-download-from", false, "Disable the download from feature")
 			fs.Bool("api-disable-health-check-logging", false, "Disable health check logging")
 			return fs
 		}(),
@@ -185,6 +198,12 @@ func (a *Api) Provision(ctx *gotenberg.Context) error {
 	a.timeout = flags.MustDuration("api-timeout")
 	a.rootPath = flags.MustString("api-root-path")
 	a.traceHeader = flags.MustString("api-trace-header")
+	a.downloadFromCfg = downloadFromConfig{
+		allowList: flags.MustRegexp("api-download-from-allow-list"),
+		denyList:  flags.MustRegexp("api-download-from-deny-list"),
+		maxRetry:  flags.MustInt("api-download-from-max-retry"),
+		disable:   flags.MustBool("api-disable-download-from"),
+	}
 	a.disableHealthCheckLogging = flags.MustBool("api-disable-health-check-logging")
 
 	// Port from env?
@@ -436,7 +455,7 @@ func (a *Api) Start() error {
 		}
 
 		if route.IsMultipart {
-			middlewares = append(middlewares, contextMiddleware(a.fs, a.timeout))
+			middlewares = append(middlewares, contextMiddleware(a.fs, a.timeout, a.downloadFromCfg))
 
 			for _, externalMultipartMiddleware := range externalMultipartMiddlewares {
 				middlewares = append(middlewares, externalMultipartMiddleware.Handler)

pkg/modules/api/context.go

@@ -3,9 +3,11 @@ package api
 import (
 	"compress/flate"
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"mime"
 	"mime/multipart"
 	"net/http"
 	"os"
@@ -14,9 +16,11 @@ import (
 	"time"
 
 	"github.com/google/uuid"
+	"github.com/hashicorp/go-retryablehttp"
 	"github.com/labstack/echo/v4"
 	"github.com/mholt/archiver/v3"
 	"go.uber.org/zap"
+	"golang.org/x/sync/errgroup"
 	"golang.org/x/text/unicode/norm"
 
 	"github.com/gotenberg/gotenberg/v8/pkg/gotenberg"
@@ -46,6 +50,14 @@ type Context struct {
 	context.Context
 }
 
+type downloadFrom struct {
+	// Url is the URL to download a file from.
+	Url string `json:"url"`
+
+	// ExtraHttpHeaders are the HTTP headers to send alongside.
+	ExtraHttpHeaders map[string]string `json:"extraHttpHeaders"`
+}
+
 type osPathRename struct{}
 
 func (o *osPathRename) Rename(oldpath, newpath string) error {
@@ -53,7 +65,7 @@ func (o *osPathRename) Rename(oldpath, newpath string) error {
 }
 
 // newContext returns a [Context] by parsing a "multipart/form-data" request.
-func newContext(echoCtx echo.Context, logger *zap.Logger, fs *gotenberg.FileSystem, timeout time.Duration) (*Context, context.CancelFunc, error) {
+func newContext(echoCtx echo.Context, logger *zap.Logger, fs *gotenberg.FileSystem, timeout time.Duration, downloadFromCfg downloadFromConfig, traceHeader, trace string) (*Context, context.CancelFunc, error) {
 	processCtx, processCancel := context.WithTimeout(context.Background(), timeout)
 
 	ctx := &Context{
@@ -126,6 +138,144 @@ func newContext(echoCtx echo.Context, logger *zap.Logger, fs *gotenberg.FileSyst
 	ctx.values = form.Value
 	ctx.files = make(map[string]string)
 
+	// First, try to download files listed in the "downloadFrom" form field, if
+	// any.
+	raw, ok := ctx.values["downloadFrom"]
+	if !downloadFromCfg.disable && ok {
+		var dls []downloadFrom
+		err = json.Unmarshal([]byte(raw[0]), &dls)
+		if err != nil {
+			return nil, cancel, WrapError(
+				fmt.Errorf("unmarshal json: %w", err),
+				NewSentinelHttpError(http.StatusBadRequest, fmt.Sprintf("Invalid 'downloadFrom' form field value: %s", err)),
+			)
+		}
+
+		eg, _ := errgroup.WithContext(ctx)
+		for i, dl := range dls {
+			eg.Go(func() error {
+				deadline, ok := ctx.Deadline()
+				if !ok {
+					// Should not happen, as context is created with a timeout.
+					return errors.New("context has no deadline")
+				}
+
+				if strings.TrimSpace(dl.Url) == "" {
+					return WrapError(
+						errors.New("empty download from URL"),
+						NewSentinelHttpError(http.StatusBadRequest, fmt.Sprintf("Invalid 'downloadFrom' form field entry %d: URL must be set", i)),
+					)
+				}
+
+				err := gotenberg.FilterDeadline(downloadFromCfg.allowList, downloadFromCfg.denyList, dl.Url, deadline)
+				if err != nil {
+					return fmt.Errorf("filter URL: %w", err)
+				}
+
+				logger.Debug(fmt.Sprintf("download file from '%s'", dl.Url))
+
+				req, err := retryablehttp.NewRequest(http.MethodGet, dl.Url, nil)
+				if err != nil {
+					return fmt.Errorf("create request to '%s': %w", dl.Url, err)
+				}
+
+				req.Header.Set("User-Agent", "Gotenberg")
+				for key, value := range dl.ExtraHttpHeaders {
+					req.Header.Set(key, value)
+				}
+				req.Header.Set(traceHeader, trace)
+
+				client := &retryablehttp.Client{
+					HTTPClient: &http.Client{
+						Timeout: time.Until(deadline),
+					},
+					RetryMax:     downloadFromCfg.maxRetry,
+					RetryWaitMin: time.Duration(1) * time.Second,
+					RetryWaitMax: time.Until(deadline),
+					Logger:       gotenberg.NewLeveledLogger(logger),
+					CheckRetry:   retryablehttp.DefaultRetryPolicy,
+					Backoff:      retryablehttp.DefaultBackoff,
+				}
+
+				resp, err := client.Do(req)
+				if err != nil {
+					return WrapError(
+						fmt.Errorf("download file from to '%s': %w", dl.Url, err),
+						NewSentinelHttpError(http.StatusBadRequest, fmt.Sprintf("Unable to download file from '%s': %s", dl.Url, err)),
+					)
+				}
+				defer func() {
+					err := resp.Body.Close()
+					if err != nil {
+						logger.Error(fmt.Sprintf("close response body from '%s': %s", dl.Url, err))
+					}
+				}()
+
+				if resp.StatusCode != http.StatusOK {
+					return WrapError(
+						fmt.Errorf("download file from to '%s': got status: '%s'", dl.Url, resp.Status),
+						NewSentinelHttpError(http.StatusBadRequest, fmt.Sprintf("Unable to download file from '%s': got status: '%s'", dl.Url, resp.Status)),
+					)
+				}
+
+				contentDisposition := resp.Header.Get("Content-Disposition")
+				if contentDisposition == "" {
+					return WrapError(
+						fmt.Errorf("no 'Content-Disposition' header from '%s'", dl.Url),
+						NewSentinelHttpError(http.StatusBadRequest, fmt.Sprintf("No 'Content-Disposition' header from '%s'", dl.Url)),
+					)
+				}
+
+				_, params, err := mime.ParseMediaType(contentDisposition)
+				if err != nil {
+					return WrapError(
+						fmt.Errorf("parse 'Content-Disposition' header '%s' from '%s': %w", contentDisposition, dl.Url, err),
+						NewSentinelHttpError(http.StatusBadRequest, fmt.Sprintf("Invalid 'Content-Disposition' header '%s' from '%s': %s", contentDisposition, dl.Url, err)),
+					)
+				}
+
+				filename, ok := params["filename"]
+				if !ok {
+					return WrapError(
+						fmt.Errorf("get filename from 'Content-Disposition' header '%s' from '%s'", contentDisposition, dl.Url),
+						NewSentinelHttpError(http.StatusBadRequest, fmt.Sprintf("Invalid 'Content-Disposition' header '%s' from '%s': no filename", contentDisposition, dl.Url)),
+					)
+				}
+
+				// Avoid directory traversal and make sure filename characters are
+				// normalized.
+				// See: https://github.com/gotenberg/gotenberg/issues/662.
+				filename = norm.NFC.String(filepath.Base(filename))
+				path := fmt.Sprintf("%s/%s", ctx.dirPath, filename)
+
+				out, err := os.Create(path)
+				if err != nil {
+					return fmt.Errorf("create local file: %w", err)
+				}
+				defer func() {
+					err := out.Close()
+					if err != nil {
+						logger.Error(fmt.Sprintf("close local file: %s", err))
+					}
+				}()
+
+				_, err = io.Copy(out, resp.Body)
+				if err != nil {
+					return fmt.Errorf("copy downloaded file from '%s' to local file: %v", dl.Url, err)
+				}
+
+				ctx.files[filename] = path
+
+				return nil
+			})
+		}
+
+		err = eg.Wait()
+		if err != nil {
+			return ctx, cancel, err
+		}
+	}
+
 	copyToDisk := func(fh *multipart.FileHeader) error {
 		in, err := fh.Open()
 		if err != nil {
@@ -149,7 +299,6 @@ func newContext(echoCtx echo.Context, logger *zap.Logger, fs *gotenberg.FileSyst
 		if err != nil {
 			return fmt.Errorf("create local file: %w", err)
 		}
-
 		defer func() {
 			err := out.Close()
 			if err != nil {
@@ -167,6 +316,7 @@ func newContext(echoCtx echo.Context, logger *zap.Logger, fs *gotenberg.FileSyst
 		return nil
 	}
 
+	// Then, copy the form files, if any.
 	for _, files := range form.File {
 		for _, fh := range files {
 			err = copyToDisk(fh)

pkg/modules/api/context_test.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -15,6 +16,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/dlclark/regexp2"
 	"github.com/google/uuid"
 	"github.com/labstack/echo/v4"
 	"go.uber.org/zap"
@@ -75,9 +77,27 @@ func TestOsPathRename_Rename(t *testing.T) {
 }
 
 func TestNewContext(t *testing.T) {
+	defaultAllowList, err := regexp2.Compile("", 0)
+	if err != nil {
+		t.Fatalf("expected no error but got: %v", err)
+	}
+	defaultDenyList, err := regexp2.Compile("", 0)
+	if err != nil {
+		t.Fatalf("expected no error but got: %v", err)
+	}
+	defaultDownloadFromCfg := downloadFromConfig{
+		allowList: defaultAllowList,
+		denyList:  defaultDenyList,
+		maxRetry:  1,
+		disable:   false,
+	}
+
 	for _, tc := range []struct {
 		scenario         string
 		request          *http.Request
+		downloadFromCfg  downloadFromConfig
+		downloadFromSrv  *echo.Echo
+		expectContext    *Context
 		expectError      bool
 		expectHttpError  bool
 		expectHttpStatus int
@@ -123,6 +143,236 @@ func TestNewContext(t *testing.T) {
 			expectHttpError:  true,
 			expectHttpStatus: http.StatusBadRequest,
 		},
+		{
+			scenario: "invalid downloadFrom form field: cannot unmarshal",
+			request: func() *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("downloadFrom", "foo")
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+				req := httptest.NewRequest(http.MethodPost, "/", body)
+				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+				return req
+			}(),
+			downloadFromCfg:  defaultDownloadFromCfg,
+			expectError:      true,
+			expectHttpError:  true,
+			expectHttpStatus: http.StatusBadRequest,
+		},
+		{
+			scenario: "invalid downloadFrom form field: no URL",
+			request: func() *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("downloadFrom", `[{}]`)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+				req := httptest.NewRequest(http.MethodPost, "/", body)
+				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+				return req
+			}(),
+			downloadFromCfg:  defaultDownloadFromCfg,
+			expectError:      true,
+			expectHttpError:  true,
+			expectHttpStatus: http.StatusBadRequest,
+		},
+		{
+			scenario: "invalid downloadFrom form field: filtered URL",
+			request: func() *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("downloadFrom", `[{"url":"https://foo.bar"}]`)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+				req := httptest.NewRequest(http.MethodPost, "/", body)
+				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+				return req
+			}(),
+			downloadFromCfg: func() downloadFromConfig {
+				denyList, err := regexp2.Compile("https://foo.bar", 0)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+				return downloadFromConfig{allowList: defaultAllowList, denyList: denyList, maxRetry: 1, disable: false}
+			}(),
+			expectError: true,
+		},
+		{
+			scenario: "invalid downloadFrom form field: unreachable URL",
+			request: func() *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("downloadFrom", `[{"url":"http://localhost:80/"}]`)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+				req := httptest.NewRequest(http.MethodPost, "/", body)
+				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+				return req
+			}(),
+			downloadFromCfg:  defaultDownloadFromCfg,
+			expectError:      true,
+			expectHttpError:  true,
+			expectHttpStatus: http.StatusBadRequest,
+		},
+		{
+			scenario: "invalid downloadFrom form field: invalid status code",
+			request: func() *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("downloadFrom", `[{"url":"http://localhost:80/"}]`)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+				req := httptest.NewRequest(http.MethodPost, "/", body)
+				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+				return req
+			}(),
+			downloadFromSrv: func() *echo.Echo {
+				srv := echo.New()
+				srv.HideBanner = true
+				srv.GET("/", func(c echo.Context) error {
+					return c.String(http.StatusNotFound, http.StatusText(http.StatusNotFound))
+				})
+				return srv
+			}(),
+			downloadFromCfg:  defaultDownloadFromCfg,
+			expectError:      true,
+			expectHttpError:  true,
+			expectHttpStatus: http.StatusBadRequest,
+		},
+		{
+			scenario: "invalid downloadFrom form field: no 'Content-Disposition' header",
+			request: func() *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("downloadFrom", `[{"url":"http://localhost:80/"}]`)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+				req := httptest.NewRequest(http.MethodPost, "/", body)
+				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+				return req
+			}(),
+			downloadFromSrv: func() *echo.Echo {
+				srv := echo.New()
+				srv.HideBanner = true
+				srv.GET("/", func(c echo.Context) error {
+					return c.String(http.StatusOK, http.StatusText(http.StatusOK))
+				})
+				return srv
+			}(),
+			downloadFromCfg:  defaultDownloadFromCfg,
+			expectError:      true,
+			expectHttpError:  true,
+			expectHttpStatus: http.StatusBadRequest,
+		},
+		{
+			scenario: "invalid downloadFrom form field: malformed 'Content-Disposition' header",
+			request: func() *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("downloadFrom", `[{"url":"http://localhost:80/"}]`)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+				req := httptest.NewRequest(http.MethodPost, "/", body)
+				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+				return req
+			}(),
+			downloadFromSrv: func() *echo.Echo {
+				srv := echo.New()
+				srv.HideBanner = true
+				srv.GET("/", func(c echo.Context) error {
+					c.Response().Header().Set(echo.HeaderContentDisposition, ";;")
+					return c.String(http.StatusOK, http.StatusText(http.StatusOK))
+				})
+				return srv
+			}(),
+			downloadFromCfg:  defaultDownloadFromCfg,
+			expectError:      true,
+			expectHttpError:  true,
+			expectHttpStatus: http.StatusBadRequest,
+		},
+		{
+			scenario: "invalid downloadFrom form field: no filename parameter in 'Content-Disposition' header",
+			request: func() *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("downloadFrom", `[{"url":"http://localhost:80/"}]`)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
+				req := httptest.NewRequest(http.MethodPost, "/", body)
+				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
+				return req
+			}(),
+			downloadFromSrv: func() *echo.Echo {
+				srv := echo.New()
+				srv.HideBanner = true
+				srv.GET("/", func(c echo.Context) error {
+					c.Response().Header().Set(echo.HeaderContentDisposition, "inline;")
+					return c.String(http.StatusOK, http.StatusText(http.StatusOK))
+				})
+				return srv
+			}(),
+			downloadFromCfg:  defaultDownloadFromCfg,
+			expectError:      true,
+			expectHttpError:  true,
+			expectHttpStatus: http.StatusBadRequest,
+		},
 		{
 			scenario: "success",
 			request: func() *http.Request {
@@ -146,17 +396,69 @@ func TestNewContext(t *testing.T) {
 				if err != nil {
 					t.Fatalf("expected no error but got: %v", err)
 				}
+				err = writer.WriteField("downloadFrom", `[{"url":"http://localhost:80/","extraHttpHeaders":{"X-Foo":"Bar"}}]`)
+				if err != nil {
+					t.Fatalf("expected no error but got: %v", err)
+				}
 				req := httptest.NewRequest(http.MethodPost, "/", body)
 				req.Header.Set(echo.HeaderContentType, writer.FormDataContentType())
 				return req
 			}(),
+			downloadFromSrv: func() *echo.Echo {
+				srv := echo.New()
+				srv.HideBanner = true
+				srv.GET("/", func(c echo.Context) error {
+					if c.Request().Header.Get("User-Agent") != "Gotenberg" {
+						t.Fatalf("expected 'Gotenberg' from header 'User-Agent', but got '%s'", c.Request().Header.Get("User-Agent"))
+					}
+					if c.Request().Header.Get("X-Foo") != "Bar" {
+						t.Fatalf("expected 'Bar' from header 'X-Foo', but got '%s'", c.Request().Header.Get("X-Foo"))
+					}
+					if c.Request().Header.Get("Gotenberg-Trace") != "123" {
+						t.Fatalf("expected '123' from header 'Gotenberg-Trace', but got '%s'", c.Request().Header.Get("Gotenberg-Trace"))
+					}
+					c.Response().Header().Set(echo.HeaderContentDisposition, `attachment; filename="bar.txt"`)
+					c.Response().Header().Set(echo.HeaderContentType, "text/plain")
+					return c.String(http.StatusOK, http.StatusText(http.StatusOK))
+				})
+				return srv
+			}(),
+			downloadFromCfg: defaultDownloadFromCfg,
+			expectContext: &Context{
+				values: map[string][]string{
+					"foo": {"foo"},
+					"downloadFrom": {
+						`[{"url":"http://localhost:80/","extraHttpHeaders":{"X-Foo":"Bar"}}]`,
+					},
+				},
+				files: map[string]string{
+					"foo.txt": "foo.txt",
+					"bar.txt": "bar.txt", // downloadFrom.
+				},
+			},
 			expectError:     false,
 			expectHttpError: false,
 		},
 	} {
 		t.Run(tc.scenario, func(t *testing.T) {
+			if tc.downloadFromSrv != nil {
+				go func() {
+					err := tc.downloadFromSrv.Start(":80")
+					if !errors.Is(err, http.ErrServerClosed) {
+						t.Error(err)
+						return
+					}
+				}()
+				defer func() {
+					err := tc.downloadFromSrv.Shutdown(context.TODO())
+					if err != nil {
+						t.Error(err)
+					}
+				}()
+			}
+
 			handler := func(c echo.Context) error {
-				_, cancel, err := newContext(c, zap.NewNop(), gotenberg.NewFileSystem(), time.Duration(10)*time.Second)
+				ctx, cancel, err := newContext(c, zap.NewNop(), gotenberg.NewFileSystem(), time.Duration(10)*time.Second, tc.downloadFromCfg, "Gotenberg-Trace", "123")
 				defer cancel()
 				// Context already cancelled.
 				defer cancel()
@@ -165,6 +467,20 @@ func TestNewContext(t *testing.T) {
 					return err
 				}
 
+				if tc.expectContext != nil {
+					if !reflect.DeepEqual(tc.expectContext.values, ctx.values) {
+						t.Fatalf("expected context.values to be %v but got %v", tc.expectContext.values, ctx.values)
+					}
+					if len(tc.expectContext.files) != len(ctx.files) {
+						t.Fatalf("expected context.files to contain %d items but got %d", len(tc.expectContext.files), len(ctx.files))
+					}
+					for key, value := range tc.expectContext.files {
+						if !strings.HasSuffix(ctx.files[key], value) {
+							t.Fatalf("expected context.files to contain '%s' but got '%s'", value, ctx.files[key])
+						}
+					}
+				}
+
 				return nil
 			}
 

pkg/modules/api/middlewares.go

@@ -236,14 +236,16 @@ func basicAuthMiddleware(username, password string) echo.MiddlewareFunc {
 //
 //	ctx := c.Get("context").(*api.Context)
 //	cancel := c.Get("cancel").(context.CancelFunc)
-func contextMiddleware(fs *gotenberg.FileSystem, timeout time.Duration) echo.MiddlewareFunc {
+func contextMiddleware(fs *gotenberg.FileSystem, timeout time.Duration, downloadFromCfg downloadFromConfig) echo.MiddlewareFunc {
 	return func(next echo.HandlerFunc) echo.HandlerFunc {
 		return func(c echo.Context) error {
 			logger := c.Get("logger").(*zap.Logger)
+			traceHeader := c.Get("traceHeader").(string)
+			trace := c.Get("trace").(string)
 
 			// We create a context with a timeout so that underlying processes are
 			// able to stop early and handle correctly a timeout scenario.
-			ctx, cancel, err := newContext(c, logger, fs, timeout)
+			ctx, cancel, err := newContext(c, logger, fs, timeout, downloadFromCfg, traceHeader, trace)
 			if err != nil {
 				cancel()
 

pkg/modules/api/middlewares_test.go

@@ -458,10 +458,11 @@ func TestContextMiddleware(t *testing.T) {
 
 		c := srv.NewContext(tc.request, recorder)
 		c.Set("logger", zap.NewNop())
+		c.Set("traceHeader", "Gotenberg-Trace")
 		c.Set("trace", "foo")
 		c.Set("startTime", time.Now())
 
-		err := contextMiddleware(gotenberg.NewFileSystem(), time.Duration(10)*time.Second)(tc.next)(c)
+		err := contextMiddleware(gotenberg.NewFileSystem(), time.Duration(10)*time.Second, downloadFromConfig{})(tc.next)(c)
 
 		if tc.expectErr && err == nil {
 			t.Errorf("test %d: expected error but got: %v", i, err)

pkg/modules/webhook/client.go

@@ -27,9 +27,9 @@ type client struct {
 
 // send call the webhook either to send the success response or the error response.
 func (c client) send(body io.Reader, headers map[string]string, erroed bool) error {
-	URL := c.url
+	url := c.url
 	if erroed {
-		URL = c.errorUrl
+		url = c.errorUrl
 	}
 
 	method := c.method
@@ -37,9 +37,9 @@ func (c client) send(body io.Reader, headers map[string]string, erroed bool) err
 		method = c.errorMethod
 	}
 
-	req, err := retryablehttp.NewRequest(method, URL, body)
+	req, err := retryablehttp.NewRequest(method, url, body)
 	if err != nil {
-		return fmt.Errorf("create '%s' request to '%s': %w", method, URL, err)
+		return fmt.Errorf("create '%s' request to '%s': %w", method, url, err)
 	}
 
 	req.Header.Set("User-Agent", "Gotenberg")
@@ -75,17 +75,17 @@ func (c client) send(body io.Reader, headers map[string]string, erroed bool) err
 
 	resp, err := c.client.Do(req)
 	if err != nil {
-		return fmt.Errorf("send '%s' request to '%s': %w", method, URL, err)
+		return fmt.Errorf("send '%s' request to '%s': %w", method, url, err)
 	}
 
 	if resp.StatusCode >= http.StatusBadRequest {
-		return fmt.Errorf("send '%s' request to '%s': got status: '%s'", method, URL, resp.Status)
+		return fmt.Errorf("send '%s' request to '%s': got status: '%s'", method, url, resp.Status)
 	}
 
 	defer func() {
 		err := resp.Body.Close()
 		if err != nil {
-			c.logger.Error(fmt.Sprintf("close response body from '%s': %s", URL, err))
+			c.logger.Error(fmt.Sprintf("close response body from '%s': %s", url, err))
 		}
 	}()
 
@@ -94,7 +94,7 @@ func (c client) send(body io.Reader, headers map[string]string, erroed bool) err
 
 	// Now let's log!
 	fields := make([]zap.Field, 5)
-	fields[0] = zap.String("webhook_url", URL)
+	fields[0] = zap.String("webhook_url", url)
 	fields[1] = zap.String("method", method)
 	fields[2] = zap.Int64("latency", int64(finishTime.Sub(c.startTime)))
 	fields[3] = zap.String("latency_human", finishTime.Sub(c.startTime).String())
@@ -110,34 +110,3 @@ func (c client) send(body io.Reader, headers map[string]string, erroed bool) err
 
 	return nil
 }
-
-// leveledLogger is wrapper around a [zap.Logger] which is used by the
-// [retryablehttp.Client].
-type leveledLogger struct {
-	logger *zap.Logger
-}
-
-// Error logs a message at error level using the wrapped zap.Logger.
-func (leveled leveledLogger) Error(msg string, keysAndValues ...interface{}) {
-	leveled.logger.Error(fmt.Sprintf("%s: %+v", msg, keysAndValues))
-}
-
-// Warn logs a message at warning level using the wrapped zap.Logger.
-func (leveled leveledLogger) Warn(msg string, keysAndValues ...interface{}) {
-	leveled.logger.Warn(fmt.Sprintf("%s: %+v", msg, keysAndValues))
-}
-
-// Info logs a message at info level using the wrapped zap.Logger.
-func (leveled leveledLogger) Info(msg string, keysAndValues ...interface{}) {
-	leveled.logger.Info(fmt.Sprintf("%s: %+v", msg, keysAndValues))
-}
-
-// Debug logs a message at debug level using the wrapped zap.Logger.
-func (leveled leveledLogger) Debug(msg string, keysAndValues ...interface{}) {
-	leveled.logger.Debug(fmt.Sprintf("%s: %+v", msg, keysAndValues))
-}
-
-// Interface guards.
-var (
-	_ retryablehttp.LeveledLogger = (*leveledLogger)(nil)
-)

pkg/modules/webhook/middleware.go

@@ -100,11 +100,11 @@ func webhookMiddleware(w *Webhook) api.Middleware {
 					}
 
 					// What about extra HTTP headers?
-					var extraHTTPHeaders map[string]string
+					var extraHttpHeaders map[string]string
 
-					extraHTTPHeadersJSON := c.Request().Header.Get("Gotenberg-Webhook-Extra-Http-Headers")
-					if extraHTTPHeadersJSON != "" {
-						err = json.Unmarshal([]byte(extraHTTPHeadersJSON), &extraHTTPHeaders)
+					extraHttpHeadersJson := c.Request().Header.Get("Gotenberg-Webhook-Extra-Http-Headers")
+					if extraHttpHeadersJson != "" {
+						err = json.Unmarshal([]byte(extraHttpHeadersJson), &extraHttpHeaders)
 						if err != nil {
 							return api.WrapError(
 								fmt.Errorf("unmarshal webhook extra HTTP headers: %w", err),
@@ -118,7 +118,7 @@ func webhookMiddleware(w *Webhook) api.Middleware {
 						method:           webhookMethod,
 						errorUrl:         webhookErrorUrl,
 						errorMethod:      webhookErrorMethod,
-						extraHttpHeaders: extraHTTPHeaders,
+						extraHttpHeaders: extraHttpHeaders,
 						startTime:        c.Get("startTime").(time.Time),
 
 						client: &retryablehttp.Client{
@@ -128,11 +128,9 @@ func webhookMiddleware(w *Webhook) api.Middleware {
 							RetryMax:     w.maxRetry,
 							RetryWaitMin: w.retryMinWait,
 							RetryWaitMax: w.retryMaxWait,
-							Logger: leveledLogger{
-								logger: ctx.Log(),
-							},
-							CheckRetry: retryablehttp.DefaultRetryPolicy,
-							Backoff:    retryablehttp.DefaultBackoff,
+							Logger:       gotenberg.NewLeveledLogger(ctx.Log()),
+							CheckRetry:   retryablehttp.DefaultRetryPolicy,
+							Backoff:      retryablehttp.DefaultBackoff,
 						},
 						logger: ctx.Log(),
 					}