Publishing Tekton Resources as bundles on OCI registry

In my previous article I showed you how to reference your Tasks from OCI bundles in your Tekton manifest. Now in this article I’ll show you how to create your own Tekton bundle, push it to remote registry and reference that in your Tekton manifest.

Pre-requisites

• tkn CLI (min version required is 0.18.x)
• Docker CLI (to login to remote registry)

Introduction

So, before understanding how the tkn bundle CLI works, let’s first see how the tekton bundle looks like

{
   "schemaVersion": 2,
   "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
   "config": {
      "mediaType": "application/vnd.docker.container.image.v1+json",
      "size": 233,
      "digest": "sha256:d99714b4b2b38402752875780d9d73fa003ce3c10f4cb553e21e940bc90cf005"
   },
   "layers": [
      {
         "mediaType": "application/vnd.docker.image.rootfs.diff.tar.gzip",
         "size": 1653,
         "digest": "sha256:f8001b6a406d0c0c82b5c7d5df7d22a8213424e3f3b973d7e0d4d86502b5696d",
         "annotations": {
            "dev.tekton.image.apiVersion": "v1beta1",
            "dev.tekton.image.kind": "task",
            "dev.tekton.image.name": "maven"
         }
      }
   ]
}

The Tekton resources are stored as layers and and each layer represents on Tekton resource. The above image just contains only one Tekton Task but the image can hold at max ten Tekton resources which includes Task, Pipeline, etc. For more you can refer Tekton Bundle Contract.

tkn has a bundle sub-command which can help to create a bundle, push it to remote registry and list the tekton resources present in a tekton bundle.

$ tkn bundle --help 
Manage Tekton Bundles
Usage:
tkn bundle [flags]
tkn bundle [command]
Aliases:
  bundle, tkb, bundles
Available Commands:
  list        List and print a Tekton bundle's contents
  push        Create or replace a Tekton bundle
Flags:
  -h, --help       help for bundle
  -C, --no-color   disable coloring (default: false)
Use "tkn bundle [command] --help" for more information about a command.

Now I am going to demonstrate each command below.

tkn bundle push

This command is used to create a bundle and push it to remote registry. To see all the options available you run the help command as shown below:

$ tkn bundle push --help

Before running this command make sure you are authenticated to the remote image registry and valid credentials should be present in .docker/config.json in order to push to that registry.

Now let’s try to push a manifest to remote registry

$ cat <<EOF > task.yaml
apiVersion: tekton.dev/v1beta1
kind: Task
metadata:
  name: demo-task
spec:
  steps:
    - image: ubuntu
      env:
      - name: HOME
        value: /tekton/home
      script: |
        #!/usr/bin/env bash
        [[ $HOME == /tekton/home ]]
EOF

after creating the task.yaml now you can run the command

$ tkn bundle push quay.io/vinamra2807/bundle:task -f task.yaml
Creating Tekton Bundle:
 - Added Task: demo-task to image
Pushed Tekton Bundle to quay.io/vinamra2807/bundle@sha256:9849a17a80eea5a460cf919acd426e72842453cac189957b15014f6236ef0e65

Create a pipeline.yaml manifest by running:

$ cat <<EOF > pipeline.yaml
apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: demo-pipeline
spec:
  tasks:
    - name: task-1
      taskRef:
        name: demo-task
---
apiVersion: tekton.dev/v1beta1
kind: PipelineRun
metadata:
  name: demo-pipelinerun
spec:
  pipelineRef:
    name: demo-pipeline
EOF

Similarly you can push multiple Tekton resources using the command:

$ tkn bundle push quay.io/vinamra2807/bundle:taskpipeline -f task.yaml -f pipeline.yaml
Creating Tekton Bundle:
 - Added Task: demo-task to image
 - Added Pipeline: demo-pipeline to image
 - Added PipelineRun: demo-pipelinerun to image
Pushed Tekton Bundle to quay.io/vinamra2807/bundle@sha256:750c0724044bec5ab7fbdde1411b3d4100fa872ffa9b333120695894cf133f36

tkn bundle list

This command is used to list the Tekton resources and get the YAML of the Tekton resource. To see all the options available you run the help command as shown below:

$ tkn bundle list --help

To list all the resources in bundle run the following command:

$ tkn bundle list quay.io/vinamra2807/bundle:taskpipeline
                                              
task.tekton.dev/demo-task
pipeline.tekton.dev/demo-pipeline
pipelinerun.tekton.dev/demo-pipelinerun

To list all the particular kind of resources in bundle we can run the command:

$ tkn bundle list quay.io/vinamra2807/bundle:taskpipeline task 
task.tekton.dev/demo-task

If you want to see the YAML manifest of the particular resource then we can run the following command:

$ tkn bundle list quay.io/vinamra2807/maven:0.1 task demo-task -o yaml
apiVersion: tekton.dev/v1beta1
kind: Task
metadata:
  creationTimestamp: null
  name: demo-task
spec:
  steps:
  - env:
    - name: HOME
      value: /tekton/home
    image: ubuntu
    name: ""
    resources: {}
    script: |
      #!/usr/bin/env bash
      [[ $HOME == /tekton/home ]]

And if you want to install the Task on cluster then you can just pipe it with kubectl :

$ tkn bundle list quay.io/vinamra2807/maven:0.1 task maven -o yaml | kubectl create -f -
task.tekton.dev/demo-task created

Know Issues

There are few known issues which can improve the command:

1. The command reads auth file generated by docker login only and if somebody has only podman installed on their machine and we do podman login then tkn bundle command would not be able to take the authfile generated by podman. This issue is tracked on tektoncd/cli repo and you can find that here.
2. tkn should have it’s own sub-command to be able to login to remote registry and generate an authfile which can be referenced by tkn for future and not dependent on other cli tools such as podman or docker for the authentication. This can be tracked here.

Questions?

Follow and hit me up on Twitter @jvinamra776 if you have any questions or comments. If I’ve made a mistake or if there is something that I have missed out in this article be sure to let me know so that I can get it corrected.

Do follow me up on medium for more Tekton related stuffs 😉.