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gochro is a small docker image with chromium installed and a golang based webserver to interact wit it. It can be used to take screenshots of websites using chromium-headless and convert HTML pages to PDF.

If errors occur the error will be logged to stdout and a non information leaking error message is presented to the user.

This project is currently used on for taking website screenshots and to generate PDF reports.


This URL takes a Screenshot of with a resolution of 1024x768 and returns an image.



Send a POST request with the HTML you want to convert in the Post body to the following url.


This will return a PDF of the HTML input.


POST /html2pdf?w=1024&h=768 HTTP/1.1
Host: localhost:8000
Content-Type: application/x-www-form-urlencoded
Content-Length: 119

<head><title>Test Page</title></head>
<h1>This is a test</h1>
<p>This is a test</p>

Run server

To run this image you should use the seccomp profile provided by Jess Frazelle. The privileges on the host are needed for chromiums internal security sandbox. You can also deactivate the sandbox on chromium (would require changes in main.go) but that's a bad idea and puts your server at risk, so please use the seccomp profile instead.

I included all the necessary steps in the included Makefile to build and run everything. Be sure to use the --init switch to get rid of zombie processes of chromium.

Command Line Options

-host                  The host and port to listen of (refers to inside the container). Defaults to
-debug                 Enables debug output. Default: false
-ignore-cert-errors    Also fetch ressources from origins with untrusted certificates or cert errors.
-proxy                 Use a proxy server to connect to the internet. Please use format IP:PORT without a protocol. Example:

Only build the webserver for non docker use

The following command builds the webserver for non docker use inside the build directory

make all

Only build docker image

To only build the docker image run

make docker-update

This will download the seccomp profile, all needed base images and builds the gochro:dev tagged image.

Run the image

To run the image in interactive mode (docker output will be connected to current terminal) run

make docker-run

This will also build the image before running it. This maps the internal port 8000 to your machine.

Run the image in deamon mode

To run it in deamon mode use the following command. This will launch everything in the background. Be aware that the webserver is rerun on startup of the machine if you don't shut down the container manually.

make docker-run-daemon

Use the docker hub image

You can also use the prebuit image from dockerhub.

To pull the image run

docker pull firefart/gochro

Include in docker-compose

If you want to include this image in a docker-compose file you can use the following example. Just connect the gochronet to the other service so the containers can communicate with each other.

Please note that the in the command only applies to the network inside the docker container itself. If you want to access it from your local machine you need to add a port mapping.

version: '3.7'

    image: firefart/gochro
    init: true
    container_name: gochro
      - seccomp="chrome.json"
    command: -host
      - gochronet

    driver: bridge


Take screenshots of websites and create PDF from HTML pages using chromium and docker