Preferred method for Docker File Versioning

Question

I simply want to know how best to user docker with git? We're a team of 6. We want to make sure that everyone is using the same libraries and dependencies. We're using docker to compile our source in the localhost. Just want to know how best to do the versioning?

1. Add the Dockerfile to the source code repository
2. Create a dedicated repository for all our Dockerfiles
3. Created a dedicated repository for each Dockerfile
4. Others?

Answer 1

Use labels to add versioning information to the docker image. Keep the dockerfile and the source code together.

• the git commit and branch
• whether it's "dirty" meaning that changes were made locally on the src code from what's in git
• a CI version number (publicly visible)
• the person who built the image (not the person who last checked in git)

Add the commit number to the image. Here's a sample of what it would be like:

build-image.sh

echo '===> Building docker image...'

GIT_BRANCH=$(git name-rev --name-only HEAD | sed "s/~.*//")
GIT_COMMIT=$(git rev-parse HEAD)
GIT_COMMIT_SHORT=$(echo $GIT_COMMIT | head -c 8)
GIT_DIRTY='false'
BUILD_CREATOR=$(git config user.email)
BUILD_NUMBER="${BUILDKITE_BUILD_NUMBER-0}"
# Whether the repo has uncommitted changes
if [[ $(git status -s) ]]; then
    GIT_DIRTY='true'
fi

docker build \
  -q \
  -t quay.io/myco/servicename:latest \
  -t quay.io/myco/servicename:"$GIT_COMMIT_SHORT" \
  --build-arg GIT_BRANCH="$GIT_BRANCH" \
  --build-arg GIT_COMMIT="$GIT_COMMIT" \
  --build-arg GIT_DIRTY="$GIT_DIRTY" \
  --build-arg BUILD_CREATOR="$BUILD_CREATOR" \
  --build-arg BUILD_NUMBER="$BUILD_NUMBER" \
  .

echo "Done"
echo "Push to quay using:"
echo "  docker push quay.io/myco/servicename:latest"
echo "  docker push quay.io/myco/servicename:$GIT_COMMIT_SHORT"

Dockerfile

FROM ...

ARG GIT_COMMIT
ARG GIT_BRANCH=master
ARG GIT_DIRTY=undefined
ARG BUILD_CREATOR
ARG BUILD_NUMBER

LABEL branch=$GIT_BRANCH \
    commit=$GIT_COMMIT \
    dirty=$GIT_DIRTY \
    build-creator=$BUILD_CREATOR \
    build-number=$BUILD_NUMBER

... etc

You can then write scripts to check for the version of the image

docker inspect --format "{{.ContainerConfig.Labels.commit}}" imageid