Hacking on Cockpit

Here’s where to get the code:

$ git clone https://github.com/cockpit-project/cockpit
$ cd cockpit/

The remainder of the commands assume you’re in the top level of the Cockpit git repository checkout.

Getting the development dependencies

Cockpit uses Node.js during development. Node.js is not used at runtime. To make changes on Cockpit you’ll want to install Node.js, NPM and various development dependencies like Webpack.

On Debian or Ubuntu:

$ sudo apt-get install nodejs npm

On Fedora:

$ sudo dnf install nodejs npm

And lastly get Webpack and the development dependencies:

$ sudo npm install -g webpack
$ npm install

When relying on CI to run the test suite, this is all that is necessary to work on the JavaScript components of Cockpit.

To actually build the Cockpit binaries themselves from source (including to run the integration tests locally), you will need additional header files and other components. Check tools/cockpit.spec for the concrete Fedora build dependencies.

Note that tools/cockpit.spec is a template filled in by tools/gen-spec-dependencies, and cannot be directly parsed by dnf. The following should work in a fresh Git clone:

$ sudo dnf install dnf-utils
$ sed 's/%{npm-version:.*}/0/' tools/cockpit.spec | sudo dnf builddep --spec /dev/stdin

In addition, for testing, the following dependencies are required:

$ sudo dnf install curl expect \
    libvirt libvirt-client libvirt-daemon libvirt-python \
    python python-libguestfs python-lxml libguestfs-xfs \
    python3 libvirt-python3 \
    libguestfs-tools qemu qemu-kvm rpm-build rsync xz \


Cockpit uses the autotools and thus there are the familiar ./configure script and Makefile targets.

After a fresh clone of the Cockpit sources, you need to prepare them by running autogen.sh like this:

$ ./autogen.sh --prefix=/usr --enable-debug

As shown, autogen.sh runs ‘configure’ with the given options, and it also prepares the build tree by downloading various nodejs dependencies.

When working with a Git clone, it is therefore best to simply always run ./autogen.sh instead of ./configure.

Then run

$ make

to build everything. Cockpit has a single non-recursive Makefile. You can only run make from the top-level and it will always rebuild the whole project.

You can run unit tests of the current checkout:

$ make check

These should finish very quickly and it is good practice to do it often.

For debugging individual tests, there are compiled binaries in the build directory. For QUnit tests (JavaScript), you can run

$ ./test-server

which will output a URL to connect to with a browser, such as http://localhost:8765/dist/base1/test-dbus.html. Adjust the path for different tests and inspect the results there.

You can also run individual tests by specifying the TESTS environment variable:

$ make check TESTS=dist/base1/test-chan.html

There are also static code and syntax checks which you should run often:

$ tools/test-static-code

It is highly recommended to set this up as a git pre-push hook, to avoid pushing PRs that will fail on trivial errors:

$ ln -s ../../tools/test-static-code .git/hooks/pre-push

Running the integration test suite

Refer to the testing README for details on running the Cockpit integration tests locally.

Running eslint

Cockpit uses ESLint to automatically check JavaScript code style in .js and .jsx files.

The linter is executed within every build as a webpack preloader.

For developer convenience, the ESLint can be started explicitly by:

$ npm run eslint

Violations of some rules can be fixed automatically by:

$ npm run eslint:fix

Rules configuration can be found in the .eslintrc.json file.

Working on your local machine

It’s easy to set up your local Linux machine for rapid development of Cockpit’s JavaScript code. First install Cockpit on your local machine as described in:


Next run this command from your top level Cockpit checkout directory, and make sure to run it as the same user that you’ll use to log into Cockpit below.

$ mkdir -p ~/.local/share/
$ ln -s $(pwd)/dist ~/.local/share/cockpit

This will cause cockpit to read JavaScript and HTML files directly from the built package output directory instead of using the installed Cockpit UI files.

Now you can log into Cockpit on your local Linux machine at the following address. Use the same user and password that you used to log into your Linux desktop.


After every change to your sources, run make to update all the webpacks, and reload cockpit in your browser.

To make Cockpit again use the installed code, rather than that from your git checkout directory, run the following, and log into Cockpit again:

$ rm ~/.local/share/cockpit

Working on Cockpit using Vagrant

It is also possible to use a Vagrant virtual machine to develop Cockpit.

Most of Cockpit is written in JavaScript. Almost all of this code is found in the packages in the pkg/ subdirectory of the Cockpit git checkout.

To use Vagrant to develop Cockpit, run in its top level git checkout. In some cases you may need to use sudo with vagrant commands:

$ vagrant up

Now you can edit files in the pkg/ subdirectory of the Cockpit sources. Use make to build those sources. The changes should take effect after syncing them to the Vagrant VM. For example:

$ make && vagrant rsync

Now log into Cockpit on the vagrant VM to see your changes. Use the user name ‘admin’ and the password ‘foobar’ to log in. The Cockpit instance in vagrant should be available at the following URL:


If you want to setup automatic syncing as you edit JavaScript files you can run:

$ vagrant rsync-auto &

Installation from upstream sources

$ make
$ sudo make install
$ sudo cp src/bridge/cockpit.pam.insecure /etc/pam.d/cockpit

This will install Cockpit and all support files, and will install a simplistic PAM configuration.

If you prefer to install to a different --prefix and would prefer that make install not write outside that prefix, then specify the --enable-prefix-only option to autogen.sh. This will result in an installation of Cockpit that does not work without further tweaking. For advanced users only.

Contributing a change

Make a pull request on github.com with your change. All changes get reviewed, tested and iterated on before getting into Cockpit. The general workflow is described in the wiki. Don’t feel bad if there’s multiple steps back and forth asking for changes or tweaks before your change gets in.

You need to be familiar with git to contribute a change. Do your changes on a branch. Your change should be one or more git commits that each contain one single logical simple reviewable change, without modifications that are unrelated to the commit message.

Cockpit is a designed project. Anything that the user will see should have design done first. This is done on the wiki and mailing list.

Bigger changes need to be discussed on #cockpit or our mailing list cockpit-devel@lists.fedoraproject.org before you invest too much time and energy.

Feature changes should have a video and/or screenshots that show the change. This video should be uploaded to Youtube or another service that allows video embedding. Use a command like this to record a video including the browser frame:

$ recordmydesktop -x 1 -y 200 --width 1024 --height 576 \
    --fps 24 --freq 44100 --v_bitrate 2000000

You can also resize your browser window and move it to the right location with a script. In Firefox you can open the Scratchpad (Shift+F4) and enter the following commands:

$ window.resizeTo(1024, 576);
$ window.moveTo(1, 200);

Then run it with Ctrl+R when the browser is showing an empty tab, e.g. about:newtab. You may need to adjust the positions for your environment.

Debug logging of Cockpit processes

All messages from the various cockpit processes go to the journal and can be seen with commands like:

$ sudo journalctl -f

Much of Cockpit has more verbose internal debug logging that can be enabled when trying to track down a problem. To turn it on add a file to your system like this:

$ sudo mkdir -p /etc/systemd/system/cockpit.service.d
$ sudo sh -c 'printf "[Service]\nEnvironment=G_MESSAGES_DEBUG=cockpit-ws,cockpit-bridge\nUser=root\nGroup=\n" > /etc/systemd/system/cockpit.service.d/debug.conf'
$ sudo systemctl daemon-reload
$ sudo systemctl restart cockpit

In the above command you’ll notice the string “cockpit-ws”. This is a log domain. There are various log domains you can enable:

  • cockpit-bridge: Cockpit bridge detailed debug messages
  • cockpit-protocol: Very verbose low level traffic logging
  • cockpit-ws: Cockpit Web Service detailed debug messages
  • WebSocket: Verbose low level WebSocket logging

To revert the above logging changes:

$ sudo rm /etc/systemd/system/cockpit.service.d/debug.conf
$ sudo systemctl daemon-reload
$ sudo systemctl restart cockpit

Running Cockpit processes under a debugger

You may want to run cockpit-ws under a debugger such as valgrind or gdb. You can run these processes as your own user, although you won’t be able to debug all the authentication logic in those cases.

First of all make sure Cockpit is installed correctly. Even though we will be running cockpit-ws from the built sources this still relies on some of the right bits being installed in order for Cockpit to work (ie: PAM stack, UI files, cockpit-bridge, etc.)

This is how you would run cockpit-ws under gdb:

$ export G_DEBUG=fatal-criticals
$ export G_MESSAGES_DEBUG=cockpit-ws,cockpit-wrapper,cockpit-bridge
$ gdb --args ./cockpit-ws --port 10000 --no-tls

And you can run cockpit-ws and cockpit-bridge under valgrind like this:

$ export G_DEBUG=fatal-criticals
$ export G_MESSAGES_DEBUG=cockpit-ws,cockpit-wrapper,cockpit-bridge
$ valgrind --trace-children=yes --trace-children-skip='*unix_chkpwd*' \
      ./cockpit-ws --port 10000 --no-tls

Note that cockpit-session and cockpit-bridge will run from the installed prefix, rather than your build tree.

Running Microsoft Edge to test Cockpit

While running Firefox or Chrome on your Linux or Mac development machine may be easy, some people find it harder to test Edge . To use the following method you need access to the windows-10 testing image. This image cannot be freely distributed for licensing reasons.

Make sure you have the virt-viewer package installed on your Linux machine. And then run the following from the Cockpit checkout directory:

$ test/vm-run --network windows-10

If the image is not yet downloaded, it’ll take a while to download and you’ll see progress on the command line. A screen will pop up and Windows will boot. Various command lines will show up once Windows has started. Ignore or minimize them, before starting Edge.

Type the following into Edge’s address bar to access Cockpit running on your development machine: