cb - a Container Builder

It builds container images locally using Google Cloud Container Builder config file.

Why not just do docker build? It will be useful to provide an easy way to manage multiple steps builds.

• We love small docker images:
  • Don't want to contain golang environment. We love a single go binary docker image.
  • Don't Want to contain frontend js build environment for a web app.

What it looks like?

steps:
- name: gcr.io/cloud-builders/docker
  args: ["build", "-t", "cb-build", "-f", "Dockerfile.build", "."]
- name: cb-build
  args: ["cp", "/go/src/cb/cb", "/workspace"]
- name: gcr.io/cloud-builders/docker
  args: ["build", "-t", "cb", "."]

This is an example config file. It will build a golang single binary image of cb command itself (not useful though).

• 1st step - Build a temporary image. It builds a go binary using golang base image as usual.
• 2nd step - Run the resulted image of 1st step. It copies the golang binary in the image to workspace volume.
• 3rd step - Build a final image from scratch. Just add the cb command from workplace volume.

$ docker images
REPOSITORY      TAG          IMAGE ID            CREATED             SIZE
cb              latest       05994f135ea4        2 days ago          3.208 MB
cb-build        latest       61f9b946f604        2 days ago          680.9 MB
...

Install

go get -u github.com/hiroshi/cb

Make sure you have $GOPATH/bin in your $PATH.

Usage

cb SOURCE.tar.gz --config CONFIG.(json|yml)

Notes

• The source field in config will be ignored as well as gcloud alpha container builds create do. Specify SOURCE as 1st argument.
• The images field in config will be ignored. The cb command is intended for local builds so always pushing images are not supposed to be welcome.

How it works

• 1. Create a volume for workspace with docker volume create.
• 2. Expand SOURCE into the workspace volume with docker copy.
• 3. docker run an image with volumes /var/run/docker.sock//var/run/docker.sock/, WORKSPACE_VOLUME:/workspace.
  • If the image have docker command like this, you can do docker build or anything in container with SOURCE at hand.
• 4. Repeat 3) with different image and args as you specifed in steps field of CONFIG.

Do you get it? No? See and run examples, I hope it may help you understand.

Examples

make run-example

TODO

• Support wait_for and id fields of steps

References

• Build request - Google Cloud Container Builder
• gcloud alpha container builds create