Custom Parameters #

Using the {{ param }} syntax, Pipelines-as-Code let you expand a variable or the payload body inside a template within your PipelineRun.

By default, there are several variables exposed according to the event. To view all the variables exposed by default, refer to the documentation on Authoring PipelineRuns.

With the custom parameter, you can specify some custom values to be replaced inside the template.

Utilizing the Tekton PipelineRun parameters feature may generally be the preferable approach, and custom params expansion should only be used in specific scenarios where Tekton params cannot be used.

As an example here is a custom variable in the Repository CR spec:

spec:
  params:
    - name: company
      value: "My Beautiful Company"

The variable name {{ company }} will be replaced by My Beautiful Company anywhere inside your PipelineRun (including the remotely fetched task).

Alternatively, the value can be retrieved from a Kubernetes Secret. For instance, the following code will retrieve the value for the company parameter from a secret named my-secret and the key companyname:

spec:
  params:
    - name: company
      secret_ref:
        name: my-secret
        key: companyname

• If you have a value and a secret_ref defined, the value will be used.
• If you don’t have a value or a secret_ref the parameter will not be parsed, it will be shown as {{ param }} in the PipelineRun.
• If you don’t have a name in the params the parameter will not parsed.
• If you have multiple params with the same name the last one will be used.

CEL filtering on custom parameters #

You can define a param to only apply the custom parameters expansion when some conditions has been matched on a filter:

spec:
  params:
    - name: company
      value: "My Beautiful Company"
      filter: pac.event_type == "pull_request"

The pac prefix contains all the values as set by default in the templates variables. Refer to the Authoring PipelineRuns documentation for all the variable exposed by default.

The body of the payload is exposed inside the body prefix.

For example if you are running a Pull Request on GitHub pac will receive a payload which has this kind of json:

{
  "action": "opened",
  "number": 79,
  // .... more data
}

The filter can then do something like this:

spec:
  params:
    - name: company
      value: "My Beautiful Company"
      filter: body.action == "opened" && pac.event_type == "pull_request"

The payload of the event contains much more information that can be used with the CEL filter. To see the specific payload content for your provider, refer to the API documentation

You can have multiple params with the same name and different filters, the first param that matches the filter will be picked up. This let you have different output according to different event, and for example combine a push and a pull request event.

• GitHub Documentation for webhook events
• GitLab Documentation for webhook events