Pipelines Questions

For more background see the guide on Serverless Jenkins X Pipelines using Tekton. There is also the Jenkins X Pipelines Syntax Reference

How do I add a custom step?

To add a new custom step to your jenkins-x.yml file see how to use the jx create step

How do I override a step?

If there is a named step in the pipeline you wish to override you can add some YAML to your jenkins-x.yml file as follows:

In this case were are going to replace the step called helm-release in the release pipeline

pipelineConfig:
  pipelines:
    overrides:
      - pipeline: release
        name: helm-release
        step: 
          image: busybox
          sh: echo "this command is replaced"

You can see the effect of this change locally before you commit it to git via the jx step syntax effective command:

jx step syntax effective -s

You can override whole Stages or replace a specific step with a single step or a sequence of steps. You can also add steps before/after another step.

For more detail check out how to override steps

How can I override the default container image?

As you can see above you can override any step in any build pack; but you can also override the container image used by default in all the steps by adding this YAML to your jenkins-x.yml:

pipelineConfig:
  agent:
    label: jenkins-go
    container: somerepo/my-container-image:1.2.3

You can see the effect of this change locally before you commit it to git via the jx step syntax effective command:

jx step syntax effective -s

For more detail check out how to override steps

How do Jenkins X Pipelines compare to Jenkins pipelines?

See Jenkins X Pipelines

What environment variables are available by default inside a pipeline?

See the default environment variables created for pipeline steps

Is there a reference for the syntax?

See the Jenkins X Pipelines Syntax Reference

How do I mount a Secret or ConfigMap?

Each step in a Jenkins X Pipeline in the jenkins-x.yml file is basically a Container from kubernetes so you can specify the image, resource limits, environment variables and mount them from a ConfigMap or Secret

You can see an example of mounting a Secret to an environment variable here

If you are inside a shell script you can also use the jx step credential

Can I mount a Persistent Volume in my pipeline?

Tekton already mounts a separate Persistent Volume for each build pod at /workspace so the build results are kept around for a while until they are garbage collected.

On most kubernetes clusters you cannot easily share a single Persistent Volume across multiple pods; so having a shared PV across builds isn’t generally easy or compatible. You can however add a step to populate your PV on startup from a cloud bucket and at the end of a pipeline copy data into a bucket to speed up caching.

You can also do things like use Nexus as a network cache for fetching maven dependencies (which happens OOTB with Maven builds in Jenkins X) or add the Athens proxy for Go.

Hopefully the Tekton community will figure out some even better caching solutions to speed up builds.

How do I define an environment variable inside a step for other steps to use?

Files are the easiest approach as the /workspace directory is shared with all steps. So write in one step and use the value from other steps etc.

The other option is mounting a ConfigMap as environment variables into each step and modifying that on one step; but files are easier really.

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