Welcome to Shipwright

Shipwright is an extensible framework for building container images on Kubernetes.

Shipwright supports popular tools such as Kaniko, Cloud Native Buildpacks, Buildah, and more!

Shipwright is based around four elements for each build:

  1. Source code - the “what” you are trying to build
  2. Output image - “where” you are trying to deliver your application
  3. Build strategy - “how” your application is assembled
  4. Invocation - “when” you want to build your application

Comparison with local image builds

Developers who use Docker are familiar with this process:

  1. Clone source from a git-based repository (“what”)
  2. Build the container image (“when” and “how”)
docker build -t registry.mycompany.com/myorg/myapp:latest .
  1. Push the container image to your registry (“where”)
docker push registry.mycompany.com/myorg/myapp:latest

Shipwright Build APIs

Shipwright’s Build API consists of four core CustomResourceDefinitions (CRDs):

  1. Build - defines what to build, and where the application should be delivered.
  2. BuildStrategy and ClusterBuildStrategy - defines how to build an application for an image building tool.
  3. BuildRun - invokes the build. You create a BuildRun to tell Shipwright to start building your application.

Build

The Build object provides a playbook on how to assemble your specific application. The simplest build consists of a git source, a build strategy, and an output image:

apiVersion: build.dev/v1alpha1
kind: Build
metadata:
  name: kaniko-golang-build
  annotations:
    build.build.dev/build-run-deletion: "true"
spec:
  source:
    url: https://github.com/sbose78/taxi
  strategy:
    name: kaniko
    kind: ClusterBuildStrategy
  output:
    image: registry.mycompany.com/my-org/taxi-app:latest

Builds can be extended to push to private registries, use a different Dockerfile, and more.

BuildStrategy and ClusterBuildStrategy

BuildStrategy and ClusterBuildStrategy are related APIs to define how a given tool should be used to assemble an application. They are distinguished by their scope - BuildStrategy objects are namespace scoped, whereas ClusterBuildStrategy objects are cluster scoped.

The spec of a BuildStrategy or ClusterBuildStrategy consists of a buildSteps object, which look and feel like Kubernetes container specifications. Below is an example spec for Kaniko, which can build an image from a Dockerfile within a container:

# this is a fragment of a manifest
spec:
  buildSteps:
    - name: build-and-push
      image: gcr.io/kaniko-project/executor:v1.3.0
      workingDir: /workspace/source
      securityContext:
        runAsUser: 0
        capabilities:
          add:
            - CHOWN
            - DAC_OVERRIDE
            - FOWNER
            - SETGID
            - SETUID
            - SETFCAP
      env:
        - name: DOCKER_CONFIG
          value: /tekton/home/.docker
      command:
        - /kaniko/executor
      args:
        - --skip-tls-verify=true
        - --dockerfile=$(build.dockerfile)
        - --context=/workspace/source/$(build.source.contextDir)
        - --destination=$(build.output.image)
        - --oci-layout-path=/workspace/output/image
        - --snapshotMode=redo
      resources:
        limits:
          cpu: 500m
          memory: 1Gi
        requests:
          cpu: 250m
          memory: 65Mi

BuildRun

Each BuildRun object invokes a build on your cluster. You can think of these as a Kubernetes Jobs or Tekton TaskRuns - they represent a workload on your cluster, ultimately resulting in a running Pod. See BuildRun for more details.

Further reading

Last modified June 5, 2022: Create "Builds" Section (8580e0b)