Configuration
The Docker image internally employs a binary that offers flags to configure its multiple modules. This guide contains a comprehensive list of flags that you can use to fine-tune Gotenberg according to your specific requirements.
API
The API module is an HTTP/1 and HTTP/2 (H2C) server.
The following flags allow you to configure the API module:
| Flag | Description | Default |
|---|---|---|
| --api-port | Set the port on which the API should listen. | 3000 |
| --api-port-from-env | Set the environment variable with the port on which the API should listen - override the default port. | None |
| --api-start-timeout | Set the time limit for the API to start. | 30s |
| --api-timeout | Set the time limit for requests. | 30s |
| --api-root-path | Set the root path of the API - for service discovery via URL paths. | / |
| --api-trace-header | Set the header name to use for identifying requests. | Gotenberg-Trace |
| --api-enable-basic-auth | Enable basic authentication - will look for the GOTENBERG_API_BASIC_AUTH_USERNAME and GOTENBERG_API_BASIC_AUTH_PASSWORD environment variables. | false |
| --api-disable-health-check-logging | Disable health check logging. | false |
Chromium
The Chromium module interacts with the Chromium browser to convert HTML documents to PDF.
A single Chromium browser manages the conversions in a stateful mode, enabling quicker single conversions. However, due to a lock mechanism, a Chromium browser cannot execute parallel operations.
During periods of heavy load, incoming requests will accumulate in the queue until they are processed, time out, or the queue reaches its maximum capacity. In the latter case, the request will be terminated prematurely.
To maintain performance under heavy load, consider increasing the number of Gotenberg instances.
The amd64 Docker image uses Google Chrome stable, while other architectures use Chromium.
The armhf Docker image uses an earlier version of Chromium. See #709
for more details.
The following flags allow you to configure the Chromium module:
| Flag | Description | Default |
|---|---|---|
| --chromium-restart-after | Number of conversions after which Chromium will automatically restart. Set to 0 to disable this feature. | 0* |
| --chromium-max-queue-size | Maximum request queue size for Chromium. Set to 0 to disable this feature. | 0 |
| --chromium-auto-start | Automatically launch Chromium upon initialization if set to true; otherwise, Chromium will start at the time of the first conversion. | false |
| --chromium-start-timeout | Maximum duration to wait for Chromium to start or restart. | 20s |
| --chromium-allow-file-access-from-files | Allow file:// URIs to read other file:// URIs. | false |
| --chromium-allow-insecure-localhost | Ignore TLS/SSL errors on localhost. | false |
| --chromium-allow-list | Set the allowed URLs for Chromium using a regular expression. | All |
| --chromium-deny-list | Set the denied URLs for Chromium using a regular expression. | ^file:(?!//\/tmp/).* |
| --chromium-ignore-certificate-errors | Ignore the certificate errors. | false |
| --chromium-disable-web-security | Don't enforce the same-origin policy. | false |
| --chromium-incognito | Start Chromium with incognito mode. | false |
| --chromium-host-resolver-rules | Set custom mappings to the host resolver. | None |
| --chromium-proxy-server | Set the outbound proxy server; this switch only affects HTTP and HTTPS requests. | None |
| --chromium-clear-cache | Clear Chromium cache between each conversion. | false |
| --chromium-clear-cookies | Clear Chromium cookies between each conversion. | false |
| --chromium-disable-javascript | Disable JavaScript. | false |
| --chromium-disable-routes | Disable the routes. | false |
*Restarting Chromium currently results in memory leaks.
LibreOffice
The LibreOffice module interacts with LibreOffice to convert numerous documents to PDF, thanks to unoconv.
A single LibreOffice instance manages the conversions in a stateful mode, enabling quicker single conversions. However, due to a lock mechanism, a LibreOffice instance cannot execute parallel operations.
During periods of heavy load, incoming requests will accumulate in the queue until they are processed, time out, or the queue reaches its maximum capacity. In the latter case, the request will be terminated prematurely.
To maintain performance under heavy load, consider increasing the number of Gotenberg instances.
The following flags allow you to configure the LibreOffice module:
| Flag | Description | Default |
|---|---|---|
| --libreoffice-restart-after | Number of conversions after which LibreOffice will automatically restart. Set to 0 to disable this feature. | 10 |
| --libreoffice-max-queue-size | Maximum request queue size for LibreOffice. Set to 0 to disable this feature. | 0 |
| --libreoffice-auto-start | Automatically launch LibreOffice upon initialization if set to true; otherwise, LibreOffice will start at the time of the first conversion. | false |
| --libreoffice-start-timeout | Maximum duration to wait for LibreOffice to start or restart. | 20s |
| --libreoffice-disable-routes | Disable the routes. | false |
Switch Language
By default, LibreOffice uses the English language when it converts documents to PDF. You may override this behavior by building your own Docker image.
For instance, with the German language:
FROM gotenberg/gotenberg:8
USER root
RUN apt-get update -qq &&\
DEBIAN_FRONTEND=noninteractive apt-get install -y -qq --no-install-recommends -t bookworm-backports libreoffice-l10n-de &&\
sed -i '/de_DE.UTF-8/s/^# //g' /etc/locale.gen &&\
locale-gen &&\
# Cleanup.
# Note: the Debian image does automatically a clean after each install thanks to a hook.
# Therefore, there is no need for apt-get clean.
# See https://stackoverflow.com/a/24417119/3248473.
rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
ENV LANG de_DE.UTF-8
ENV LANGUAGE de_DE:de
ENV LC_ALL de_DE.UTF-8
USER gotenberg
PDF Engines
The PDF Engines module gathers all engines that can manipulate PDF files. It calls each engine until one successfully handles a task. A PDF engine is an external tool that Gotenberg leverages to perform a specific task, such as merging PDF files.
Currently, Gotenberg supports the following PDF engines:
| Engine | Merge | Convert into PDF/A | Read/Write metadata | Name |
|---|---|---|---|---|
| ExifTool | ❌ | ❌ | ✅ | exiftool |
| PDFtk | ✅ | ❌ | ❌ | pdtk |
| PDFcpu | ✅ | ❌ | ❌ | pdcpu |
| QPDF | ✅ | ❌ | ❌ | qpdf |
| UNO | ❌ | ✅ | ❌ | libreoffice-pdfengine |
The following flags allow you to configure the PDF Engines module:
| Flag | Description | Default |
|---|---|---|
| --pdfengines-engines | Set the PDF engines and their order. | All |
| --pdfengines-disable-routes | Disable the routes. | false |
For instance, the value "pdftk,libreoffice-pdfengine" selects PDFtk as the first engine, and UNO as the second.
Webhook
The webhook feature enables Gotenberg to upload the output file originating from multipart/form-data routes to a selected destination.
The following flags allow you to configure the Webhook module:
| Flag | Description | Default |
|---|---|---|
| --webhook-allow-list | Set the allowed URLs for the webhook feature using a regular expression. | All |
| --webhook-deny-list | Set the denied URLs for the webhook feature using a regular expression. | None |
| --webhook-error-allow-list | Set the allowed URLs in case of an error for the webhook feature using a regular expression. | All |
| --webhook-error-deny-list | Set the denied URLs in case of an error for the webhook feature using a regular expression. | None |
| --webhook-max-retry | Set the maximum number of retries for the webhook feature. | 4 |
| --webhook-retry-min-wait | Set the minimum duration to wait before trying to call the webhook again. | 1s |
| --webhook-retry-max-wait | Set the maximum duration to wait before trying to call the webhook again. | 30s |
| --webhook-client-timeout | Set the time limit for requests to the webhook. | 30s |
| --webhook-disable | Disable the webhook feature. | false |
Prometheus
The Prometheus module collects metrics from other modules and exposes an HTTP endpoint that can be scraped by Prometheus.
The following flags allow you to configure the Prometheus module:
| Flag | Description | Default |
|---|---|---|
| --prometheus-collect-interval | Set the interval for collecting modules' metrics. | 1s |
| --prometheus-namespace | Set the namespace of modules' metrics. | gotenberg |
| --prometheus-disable-collect | Disable the collect of metrics. | false |
| --prometheus-disable-route-logging | Disable the route logging. | false |
Logging
Gotenberg employs a logger that generates structured logs. Structured logs are formatted in a standardized, machine-readable way, making them extremely beneficial for centralized log management.
The following flags allow you to configure the logger:
| Flag | Description | Default |
|---|---|---|
| --log-format | Specify the format of logging. Options include auto, json, or text. | auto |
| --log-level | Choose the level of logging detail. Options include error, warn, info, or debug. | info |
| --log-fields-prefix | Prepend a specified prefix to each field in the logs. | None |
Graceful Shutdown
To ensure running tasks have sufficient time to complete, Gotenberg waits for a specific duration before initiating the shutdown process. It may stop earlier if all tasks have completed.
The following flag allows you to configure this duration:
| Flag | Description | Default |
|---|---|---|
| --gotenberg-graceful-shutdown-duration | Set the graceful shutdown duration. | 30s |
Docker Image
Fonts
The default Docker image is pre-packaged with an extensive assortment of fonts, including Asian ones. If your application requires additional or specific fonts not included in this collection, you'll need to construct a tailored Docker image to incorporate those fonts.
Via .tff files
FROM gotenberg/gotenberg:8
USER root
COPY /local/path/to/{font}.ttf /usr/local/share/fonts/{font}.ttf
USER gotenberg
Or, if you have many fonts:
FROM gotenberg/gotenberg:8
USER root
COPY /local/path/to/fonts/* /usr/local/share/fonts/
USER gotenberg
Via .deb packages
FROM gotenberg/gotenberg:8
USER root
RUN DEBIAN_FRONTEND=noninteractive apt-get install -y -qq --no-install-recommends my-fonts-package
USER gotenberg
You could also mount a volume containing your fonts to /usr/local/share/fonts/ as suggested in this comment.
Ownership
The Docker image employs a specific non-root user, named gotenberg, with a User ID (uid) and Group ID (gid) of 1001. If you want to change these identifiers, you will have to build a custom Docker image:
FROM gotenberg/gotenberg:8
USER root
RUN usermod -u {uid} -g {gid} gotenberg
USER gotenberg