Documentation / Docker



With 4.0 we focused on single Docker container that you should use to run This is the preferred installation method.

It also contains FFMpeg, Imagemagick and some other things for the future to get SpeedIndex using VisualMetrics.


The new structure looks like this:

NodeJS with Ubuntu 16 -> VisualMetrics dependencies -> Firefox/Chrome/xvfb ->

The first container installs NodeJS (latest LTS) on Ubuntu 16. The next one adds the dependencies (FFMpeg, ImageMagick and some Python libraries) needed to run VisualMetrics. Then we install specific version of Firefox, Chrome and then xvfb. It’s important to lock down the browsers to specific versions because it has been a real mess using Firefox the last half year (to be fair Chrome/Selenium have also had issues in the past). Then in last step, we add sitespeed and tag it to the version number.

Running in Docker

The simplest way to run using Firefox:

$ docker run --rm -v "$(pwd)":/ sitespeedio/ -b firefox

That will map the current directory inside Docker and output the result directory there.

If you wanna use Chrome you either need to use privileged or turn of the sandbox option:

$ docker run --privileged --shm-size=512m --rm -v "$(pwd)":/ sitespeedio/ -b chrome

Note: The shm-size increases the memory for the GPU (default is 64mb and that is too small) see


$ docker run --shm-size=512m --rm -v "$(pwd)":/ sitespeedio/ -b chrome no-sandbox

If you want to feed sitespeed with a list of URLs in a file (here named myurls.txt), add the file to your current directory and do like this:

sudo docker run --shm-size=512m --privileged --rm -v "$(pwd)":/ sitespeedio/ myurls.txt -b chrome

In the real world you should always specify the exact version (tag) of the Docker container to make sure you use the same version everytime (else you will download the latest tag, meaning you can have major changes between test runs without you even knowing). Specify the tag after the container name(X.Y.Z) in this example. The tag/version number will be the same number as the release:

sudo docker run --shm-size=512m --privileged --rm -v "$(pwd)":/ sitespeedio/ -b chrome

More about volumes

If you want to feed with a file with URLs or if you want the HTML result, you should setup a volume. will do all the work inside the container in a directory located / To setup your current working directory add the -v “$(pwd)”:/ to your parameter list. Using “$(pwd)” will default to the root user directory. In order to specify the location, simply define an absolute path: -v /Users/user/path:/

Update (download a newer

Updating to a newer version is easy, change X.Y.Z to the version you want to use:

docker pull sitespeedio/

Or alternatively pull the latest version:

docker pull sitespeedio/

And then change your start script (or where you start your container) to use the new version number.

If you don’t use version number (you should!) then just pull the container and your next run will use the latest version.


Inspect the container

In 4.0 we autostart If you wanna check what’s in the container, you can do that by changing the entry point.

docker run -it --entrypoint bash sitespeedio/

Visualize your test in XVFB

The docker containers have x11vnc installed which enables visualization of the test running inside Xvfb. To view the tests, follow these steps:

  • You will need to run the image by exposing a PORT for vnc server . By default, it is 5900. If you plan to change your port for VNC server, then you need to expose that port.
docker run --shm-size=512m --privileged --rm -v "$(pwd)":/ -p 5900:5900 sitespeedio/ -b chrome
  • Find the container id of the docker container for sitespeed by running:
docker ps
  • Enter into your running docker container for by executing:
docker exec -it <container-id> bash
  • Find the Xvfb process using ps -ef. It should be using DISPLAY=:99.
  • Run
x11vnc -display :99 -storepasswd

Enter any password. This will start your VNC server which you can use by any VNC client to view:

  • Download VNC client like RealVNC
  • Enter VNC server :
  • When prompted for password, enter the password you entered while creating the vnc server.
  • You should be able to view the contents of Xvfb.