helloworldbuild.md

As of Knative 0.8, Knative Build has been deprecated in favor of Tekton Pipelines. This doc is kept as a reference for pre-0.8 Knative installations. Please refer to Tekton Pipelines section of the tutorial on how to do builds in Knative going forward.

Knative Build utilizes existing Kubernetes primitives to provide you with the ability to run on-cluster container builds from source. For example, you can write a build that uses Kubernetes-native resources to obtain your source code from a repository, build a container image, then run that image.

The Knative Build API has a Build type that represents a single build job with one or more steps. There's also a BuildTemplate that allows you to chain Builds and parameterize them.

In the previous labs, we've been building and pushing container images manually to DockerHub. Let's utilize Knative Build and push to Google Container Registry (GCR) instead.

Design the build

Kaniko is a tool to build container images from a Dockerfile, inside a container in Kubernetes cluster. The advantage is that Kaniko doesn't depend on a Docker daemon. We'll use Kaniko in our Build step.

Create a build-helloworld-gcr.yaml build file:

apiVersion: build.knative.dev/v1alpha1
kind: Build
metadata:
  name: build-helloworld-gcr
spec:
  source:
    git:
      url: https://github.com/meteatamel/knative-tutorial.git
      revision: master
    subPath: serving/helloworld/csharp
  steps:
  - name: build-and-push
    image: "gcr.io/kaniko-project/executor:v0.6.0"
    args:
    - "--dockerfile=/workspace/Dockerfile"
    # Replace {PROJECT_ID} with your GCP Project's ID.
    - "--destination=gcr.io/{PROJECT_ID}l/helloworld:build"

This uses Knative Build to download the source code in the 'workspace' directory and then use Kaniko to build and push an image to GCR.

Run and watch the build

You can start the build with:

kubectl apply -f build-helloworld-gcr.yaml

Check that it is created:

kubectl get build

Soon after, you'll see a pod created for the build:

kubectl get pods

NAME                                             READY     STATUS
build-helloworld-gcr-pod-454bd8           0/1       Init:2/3

You can see the progress of the build with:

kubectl logs --follow --container=build-step-build-and-push <podid>

When the build is finished, you'll see the pod in Completed state:

kubectl get pods

NAME                                              READY     STATUS
build-helloworld-gcr-pod-454bd8            0/1       Completed

At this point, you should see the image pushed to GCR:

What's Next?

Docker Hub Build