Knative 0.8.0 and Build Deprecation
Knative 0.8.0 came out a couple of weeks ago with a number of fixes and improvements. One of the biggest changes in 0.8.0 is that Knative Build is now deprecated according to docs:
Knative Installation docs also only include Knative Serving and Eventing without mentioning Build:
kubectl apply -f https://github.com/knative/serving/releases/download/v0.8.0/serving.yaml \ -f https://github.com/knative/eventing/releases/download/v0.8.0/release.yaml \ -f https://github.com/knative/serving/releases/download/v0.8.0/monitoring.yaml
Good to know but there’s no explanation on why Knative Build was deprecated and any guidance on what is the replacement, if any. After a little bit of research, I have more information on deprecation and also a migration path that I’d like to share in this post.
There’s a Knative issue (614) with more details but basically, it has been decided that building and pushing an image for a service should not be one of the core responsibilities for Knative.
Instead, Knative users can rely on a number of other better tools. One of those tools is called Tekton Pipelines. Inspired by Knative Build, The Tekton Pipelines project provides Kubernetes style resources for declaring CI/CD-style pipelines. It does everything Knative Build does and some more.
Hello Tekton Pipelines
In Tekton Pipelines, you can create a simple one-off tasks or more complicated CI/CD pipelines. There are 4 main primitives for Tekton Pipelines:
- Task defines the work that needs to be executed with 1 or more steps.
- PipelineResources defines the artifacts that can be passed in and out of a task.
- TaskRun runs the Task you defined with the supplied resources.
- Pipeline defines a list of tasks to execute in order.
Before you can use Tekton Pipelines, you need to install it in your Kubernetes cluster. Detailed instructions are here but it’s as easy as:
kubectl apply -f https://storage.googleapis.com/tekton-releases/latest/release.yaml
Once you have it installed, you can check the Tekton pods:
kubectl get pods -n tekton-pipelines NAME READY STATUS tekton-pipelines-controller-55c6b5b9f6-8p749 1/1 Running tekton-pipelines-webhook-6794d5bcc8-pf5x7 1/1 Running
Knative Build ==> Tekton Pipelines
There’s basic documentation on Migrating from Knative Build to Tekton. In a nutshell, these are Tekton equivalents of Knative Build constructs:
| Knative | Tekton |
| Build | TaskRun |
| BuildTemplate | Task |
| ClusterBuildTemplate | ClusterTask |
Additionally, the Tekton Catalog aims to provide a catalog of re-usable Tasks, similar to what Knative BuildTemplate repository used to do before.
Build with Kaniko Task
As an example, let’s take a look at how to build and push an image to Google Container Registry (GCR) using Tekton Pipelines.
In Tekton world, you start with either defining your custom Task (example) or re-using someone else’s Task (example). Let’s use the Kaniko Task already available on Tekton Catalog.
First, install the Kaniko Task and make sure it’s installed:
kubectl apply -f https://raw.githubusercontent.com/tektoncd/catalog/master/kaniko/kaniko.yaml kubectl get task NAME AGE kaniko 45m
Second, define a TaskRun to use the Task and supply the required parameters:
apiVersion: tekton.dev/v1alpha1
kind: TaskRun
metadata:
name: build-kaniko-helloworld-gcr
spec:
taskRef:
name: kaniko
inputs:
resources:
- name: source
resourceSpec:
type: git
params:
- name: url
value: https://github.com/meteatamel/knative-tutorial
params:
- name: DOCKERFILE
value: Dockerfile
- name: CONTEXT
value: serving/helloworld/csharp
outputs:
resources:
- name: image
resourceSpec:
type: image
params:
- name: url
# Replace {PROJECT_ID} with your GCP Project's ID.
value: gcr.io/{PROJECT_ID}/helloworld:kaniko-tekton
Finally, start the TaskRun and check that it’s succeeded:
kubectl apply -f taskrun-build-kaniko-helloworld-gcr.yaml kubectl get taskrun NAME SUCCEEDED build-kaniko-helloworld-gcr True
At this point, you should see the container image built and pushed to GCR.
Hopefully, this blog post provided you the basics needed to move from Knative Build to Tekton Pipeliens. I also updated my Knative Tutorial for the 0.8.0 release. Check it out for more examples of converting Knative Build to Tekton Pipelines:
Mete Atamel 