How to prevent Dockerfile caching git clone

Question

I have a Dockerfile trying to package and deploy a web app to a container. The code of app fetches from git repository during Docker image building. Here\'s the Dockerfile s

Answer 1

If you use github you can use github API to not cache specific RUN command. You need to have jq installed to parse JSON: apt-get install -y jq

Example:

docker build --build-arg SHA=$(curl -s 'https://api.github.com/repos/Tencent/mars/commits' | jq -r '.[0].sha') -t imageName .

In Dockerfile (ARG command should be right before RUN):

ARG SHA=LATEST
RUN SHA=${SHA} \
    git clone https://github.com/Tencent/mars.git

or if you don't want to install jq

SHA=$(curl -s 'https://api.github.com/repos/Tencent/mars/commits' | grep sha | head -1)

If repository has new commits, git clone will be executed.