Schinckel.net

Docker + Makefile

I rewrote one of my projects (Fronius Dashboard) in Python - more because I was no longer able to get the build to work correctly under Elixir. As a side-effect, the image size went down a lot.

Part of this process is to build multiple-architectures, and publish these manifests. As an aside, being able to version them is also nice.

We’ll start with the versioning, because that’s a bit simpler.

Take a file VERSION. Put the current version into this file (x.y.z format is the only one supported so far).

Now, we can have a few tools to handle this:

.PHONY: bump-major bump-minor

requirements.txt: poetry.lock pyproject.toml
	poetry export -o requirements.txt

bump-major:
	cat VERSION | awk -F. '{print $$1 + 1 ".0.0"}' | tee VERSION
	
bump-minor:
	cat VERSION | awk -F. '{print $$1 "." $$2 + 1  ".0"}' | tee VERSION
	
VERSION: app.py requirements.txt
	cat VERSION | awk -F. '{print $$1 "." $$2 "." $$3 + 1}' | tee VERSION

This allows us to have make bump-major that adds one to the existing major version, and resets the minor and patch versions. And another version that adds one to the minor version, and resets the patch version.

There is no bump-patch, instead every file that could possibly affect the code is included in the make VERSION dependencies list. This means that make VERSION will only run if any files have changed, and in that case it will increment the patch version.

So, that’s the versioning. How about publishing docker images?

There are a couple of things that we need to do:

  • build for a number of platforms (amd64, armv6 and armv7, because I run stuff on Raspberry Pi hardware).
  • create and push a manifest of all images
  • also create and push a tagged version (ie, not just latest).
IMAGE := <image-name-goes-here>

.PHONY: release bump-major bump-minor
	
release: Dockerfile VERSION
	docker buildx build . -t $(IMAGE):armv6 --platform linux/arm/v6 --push
	docker buildx build . -t $(IMAGE):armv7 --platform linux/arm/v7 --push
	docker buildx build . -t $(IMAGE):amd64 --platform linux/amd64 --push
	
	docker pull $(IMAGE):armv6
	docker pull $(IMAGE):armv7
	docker pull $(IMAGE):amd64
	
	docker image rm --force $(IMAGE):latest
	
	docker manifest create $(IMAGE):latest \
		$(IMAGE):armv6 \
		$(IMAGE):armv7 \
		$(IMAGE):amd64 \
		--amend
	
	docker manifest annotate $(IMAGE):latest $(IMAGE):armv6 --variant v6l
	docker manifest annotate $(IMAGE):latest $(IMAGE):armv7 --variant v7l
	
	docker manifest create $(IMAGE):$(shell cat VERSION) \
		$(IMAGE):armv6 \
		$(IMAGE):armv7 \
		$(IMAGE):amd64 \
		--amend
	
	docker manifest annotate $(IMAGE):$(shell cat VERSION) $(IMAGE):armv6 --variant v6l
	docker manifest annotate $(IMAGE):$(shell cat VERSION) $(IMAGE):armv7 --variant v7l
	
	docker manifest push $(IMAGE):$(shell cat VERSION)
	docker manifest push $(IMAGE):latest

requirements.txt: poetry.lock pyproject.toml
	poetry export -o requirements.txt

bump-major:
	cat VERSION | awk -F. '{print $$1 + 1 ".0.0"}' | tee VERSION
	
bump-minor:
	cat VERSION | awk -F. '{print $$1 "." $$2 + 1  ".0"}' | tee VERSION
	
VERSION: app.py requirements.txt
	cat VERSION | awk -F. '{print $$1 "." $$2 "." $$3 + 1}' | tee VERSION

There is a bit of repetition - I’m sure I could do something using Makefile expansion, but this works for now.