Wikimedia Helm Charts

This is the repo that powers https://helm-charts.wikimedia.org/stable/.

Here you will find the various helm charts the Wikimedia Foundation uses in developing software and deploying it to production.

Creating a new chart

If you want to create a new chart:

Pre-requisites

• Python 3.9 or higher
• sextant, our tool to manage helm charts, which you can install with pip3 install sextant
• Ruby 3.0 or higher
• rake, the ruby task executor
• docker or another container engine

Steps

1. run ./create_new_service.sh
2. follow the prompts. This will create your chart under charts/<your-chart-name>
3. Modify the default chart to fit your needs
4. Validate your new chart with our CI system: rake run_locally["check_charts[lint/validate\,<your-chart-name>]"]. WARNING: on M1 macs this could be unbearably slow at the moment.
5. test the new chart in minikube. WARNING: on M1 macs this could be very slow at the moment.
6. commit and upload the change to Gerrit
7. wait for/request a review

Template names are global

If two separate charts have templates with the same names and are deployed in the same release, the last definition of the template will be used for both charts. Please take this into account when designing new charts.

Other stuff

The values.yaml files provided by any chart are defaults and their purpose is to help deployment under development clusters. Actual values used in production are not kept here.

The _scaffold/ directory is used by the create_new_service.sh script, it's best to leave it alone.

Further documenation can be found on Wikitech

Updating a Chart

If you want to update an existing chart then changes should be made to it in the charts/ directory.

The changes should include incrementing the chart's version in the respective Chart.yaml file.

The resulting files and changes should then be uploaded to Gerrit for code review.

How to use modules in a chart

Every chart created by our scaffolding will have:

• A package.json file, where the modules we're using in that chart are indicated. In this file only major.minor versions should be specified
• A package.lock file where the aforementioned dependencies are frozen to a specific version
• A templates/vendor directory where the modules at the correct version are copied. To manage these dependencies, we use a tool called sextant. Please see its README for details on its usage.

Linters and tests

Charts are linted using helm lint and helm template; the resulting templates are also checked to ensure they produce valid YAML files.

Many charts use feature flags like monitoring.enabled: true to include or omit artifacts from the generated configuration. These optional features can and should be tested by providing values overrides for each feature flag. The tests will run the lint and template steps once with just your values.yaml data and then again for each YAML file in the chart's .fixtures/ directory.

In addition to the basic linting and template validation, all service deployments under helmfile.d/services are checked by each test run. Settings expected to be loaded from puppet managed files under /etc/helmfile-defaults during a deployment are not present in the testing environment. You can provide necessary values for testing by creating a helmfile.d/services/$SERVICE/.fixtures.yaml file to simulate production data.

License

While the helm charts specification allows for a per chart license to be specified, we are following a more strict approach. All of the charts in this repo MUST have the exact same GPL-3.0-or-later license. See our LICENSE file for full license information.