kpack 101

This project shows how to use kpack, an open-source project by Pivotal, to leverage Cloud Native Buildpacks on any Kubernetes clusters.

Using kpack, you can automatically build secure Docker images from your source code, without having to write a Dockerfile. Moreover, kpack can rebase your Docker images when updates are available. Let's say you're deploying a Java app as a container image, embedding a JRE: when a new JRE version is out, kpack can update your image without having you building a new container image.

Read more about kpack in the announcement article.

This repository describes how to deploy kpack to your Kubernetes cluster, and how to use it to create your first Docker image.

Deploying kpack

Download the latest kpack release: you should have a file release-<version>.yaml.

Deploy kpack using kubectl:

$ kubectl apply -f release-<version>.yaml
namespace/kpack created
customresourcedefinition.apiextensions.k8s.io/builds.build.pivotal.io unchanged
customresourcedefinition.apiextensions.k8s.io/builders.build.pivotal.io unchanged
customresourcedefinition.apiextensions.k8s.io/clusterbuilders.build.pivotal.io unchanged
clusterrole.rbac.authorization.k8s.io/kpack-controller-admin configured
clusterrole.rbac.authorization.k8s.io/kpack-webhook-admin configured
clusterrolebinding.rbac.authorization.k8s.io/kpack-controller-admin unchanged
clusterrolebinding.rbac.authorization.k8s.io/kpack-webhook-admin unchanged
deployment.apps/kpack-controller created
customresourcedefinition.apiextensions.k8s.io/custombuilders.experimental.kpack.pivotal.io created
customresourcedefinition.apiextensions.k8s.io/customclusterbuilders.experimental.kpack.pivotal.io created
customresourcedefinition.apiextensions.k8s.io/images.build.pivotal.io unchanged
service/kpack-webhook created
serviceaccount/controller created
serviceaccount/webhook created
customresourcedefinition.apiextensions.k8s.io/sourceresolvers.build.pivotal.io unchanged
customresourcedefinition.apiextensions.k8s.io/stacks.experimental.kpack.pivotal.io created
customresourcedefinition.apiextensions.k8s.io/stores.experimental.kpack.pivotal.io created
mutatingwebhookconfiguration.admissionregistration.k8s.io/resource.webhook.kpack.pivotal.io created
deployment.apps/kpack-webhook created

Check that kpack is running:

$ kubectl -n kpack get pods
NAME                                READY   STATUS    RESTARTS   AGE
kpack-controller-5f66c774d8-cschb   1/1     Running   0          13s
kpack-webhook-847c887dd-4nncg       1/1     Running   0          13s

We'll build Docker images using a Cloud Foundry buildpack (don't worry: you can deploy the resulting Docker image anywhere 😋).

apiVersion: build.pivotal.io/v1alpha1
kind: ClusterBuilder
metadata:
  name: default
spec:
  image: cloudfoundry/cnb:bionic

Deploy this builder to your cluster:

$ kubectl apply -f cnb-builder.yml

Creating a Docker image from a Git repository using kpack

Create a secret for push access to your Docker registry. Let's create file dockerhub-creds.yml with your Docker Hub credentials:

apiVersion: v1
kind: Secret
metadata:
  name: dockerhub-creds
  annotations:
    build.pivotal.io/docker: index.docker.io
type: kubernetes.io/basic-auth
stringData:
  username: <username>
  password: <password>

Create a secret for read access to your Git repository. Create file github-creds.yml to set your GitHub credentials:

apiVersion: v1
kind: Secret
metadata:
  name: github-creds
  annotations:
    build.pivotal.io/git: https://github.com
type: kubernetes.io/basic-auth
stringData:
  username: <username>
  password: <password>

Please note you need to use a GitHub access token as your password in case you enabled 2-Factor Authentication with your account.

You need a service account using your Docker registry and your Git repository credentials:

apiVersion: v1
kind: ServiceAccount
metadata:
  name: kpack-service-account
secrets:
  - name: dockerhub-creds
  - name: github-creds

Finally, create a configuration file for building a Docker image from your Git repository:

apiVersion: build.pivotal.io/v1alpha1
kind: Image
metadata:
  name: spring-on-k8s-image
spec:
  # Set your Docker image.
  tag: alexandreroman/spring-on-k8s
  serviceAccount: kpack-service-account
  builder:
    name: default
    kind: ClusterBuilder
  cacheSize: "2Gi"
  source:
    git:
      # Set your Git repo URL.
      url: https://github.com/alexandreroman/spring-on-k8s.git
      revision: master
  build:
    env:
      - name: BP_JAVA_VERSION
        # Java 11 is used by default if BP_JAVA_VERSION is unset.
        value: 11.*

Deploy all files to your Kubernetes cluster:

$ kubectl apply -f dockerhub-creds.yml
$ kubectl apply -f github-creds.yml
$ kubectl apply -f kpack-service-account.yml
$ kubectl apply -f app-source.yml

Using kpack

Monitor kpack build status:

$ kubectl get cnbbuilds
NAME                                IMAGE   SUCCEEDED
spring-on-k8s-image-build-1-kfgz8           Unknown

Status is Unknown while image is being built.

Wait a couple of minutes, and the status will be updated:

$ kubectl get cnbbuilds                                    
NAME                                IMAGE                                                                                                                  SUCCEEDED
spring-on-k8s-image-build-1-kfgz8   index.docker.io/alexandreroman/spring-on-k8s@sha256:6188498e07a6c4e6620fd33bf7c2842f76618ae6f05f07e4146f7cf1f8cfd624   True

Go to your Docker registry: a new image is now available!

Check that your image is ready:

$ docker run --rm -p 8080:8080/tcp \
    index.docker.io/alexandreroman/spring-on-k8s@sha256:6188498e07a6c4e6620fd33bf7c2842f76618ae6f05f07e4146f7cf1f8cfd624

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.5.RELEASE)

2019-08-22 16:49:29.261  WARN 1 --- [           main] pertySourceApplicationContextInitializer : Skipping 'cloud' property source addition because not in a cloud
2019-08-22 16:49:29.277  WARN 1 --- [           main] nfigurationApplicationContextInitializer : Skipping reconfiguration because not in a cloud
2019-08-22 16:49:29.300  INFO 1 --- [           main] i.pivotal.demos.springonk8s.Application  : Starting Application on 5f2335b83afb with PID 1 (/workspace/BOOT-INF/classes started by vcap in /workspace)
2019-08-22 16:49:29.306  INFO 1 --- [           main] i.pivotal.demos.springonk8s.Application  : No active profile set, falling back to default profiles: default
2019-08-22 16:49:33.134  INFO 1 --- [           main] o.s.b.a.e.web.EndpointLinksResolver      : Exposing 2 endpoint(s) beneath base path '/actuator'
2019-08-22 16:49:34.676  INFO 1 --- [           main] o.s.b.web.embedded.netty.NettyWebServer  : Netty started on port(s): 8080
2019-08-22 16:49:34.683  INFO 1 --- [           main] i.pivotal.demos.springonk8s.Application  : Started Application in 6.237 seconds (JVM running for 7.322)

Now, update your Git repository, and monitor kpack activity:

$ kubectl get cnbbuilds
NAME                                IMAGE                                                                                                                  SUCCEEDED
spring-on-k8s-image-build-1-kfgz8   index.docker.io/alexandreroman/spring-on-k8s@sha256:6188498e07a6c4e6620fd33bf7c2842f76618ae6f05f07e4146f7cf1f8cfd624   True
spring-on-k8s-image-build-2-cbd5f                                                                                                                          Unknown

A new image is being built!

Run this command again, and you should have a new image:

$ kubectl get cnbbuilds      
NAME                                IMAGE                                                                                                                  SUCCEEDED
spring-on-k8s-image-build-1-kfgz8   index.docker.io/alexandreroman/spring-on-k8s@sha256:6188498e07a6c4e6620fd33bf7c2842f76618ae6f05f07e4146f7cf1f8cfd624   True
spring-on-k8s-image-build-2-cbd5f   index.docker.io/alexandreroman/spring-on-k8s@sha256:9ed04eb2e25f7056ae268c8441032e16feaa82de8195ebb489142d02c381fb3d   True

Contribute

Contributions are always welcome!

Feel free to open issues & send PR.

License

Copyright © 2020 VMware, Inc.

This project is licensed under the Apache Software License version 2.0.