How to read an environment variable in docker build steps


I am trying to figure out how to extract the docker tag from a ‘feature/PRO-123-my-new-feature’ branch as ‘:PRO-123’.

I have already extracted the necessary part and wrote that to a tag.txt file in the following step:

  - name: get_drone_tag
    image: debian:buster-slim
      - /bin/bash -c "echo ''DRN-$(echo ${DRONE_COMMIT_BRANCH} | awk -F'-' '{print $2}')'' >> tag.txt" 
      - cat tag.txt
      - export DOCKER_TAG=$(cat tag.txt)
      - echo $${DOCKER_TAG}

However, I am unable to use this $${DOCKER_TAG} in my docker build steps. I figured that I need to read the file in each step, but how do use the command to execute - export DOCKER_TAG=$(cat tag.txt)in each docker build step?

These are the steps I am using to build images:

x-base: &base
  <<: *docker
    repo: docker-registry
    target: build
x-feature: &feature_config
    tag: ${DOCKER_TAG}
     - refs/heads/feature/*
  - name: base-master
    <<: *base
    <<: *feature_config

Thanks for the help!

I’ve found the answer to my question in one of the previous questions.

Hello @ozangungor,

Looks like you were able to get this working by following the other thread, Let me know if you need any further assistance.

Harness Support

thanks my issue has been fixed.