Git tag name in Azure Devops Pipeline YAML

Question

Summary

How do I get the name of the current git tag in an Azure Devops Pipeline YAML-file?

What Am I Trying to Do?

I am setting up a build pipeline in Azure Devops. The pipeline triggers when a new git tag is created. I then want to build docker images and tag them with the git tag's name.

My YAML pipeline looks something like this:

# Trigger on new tags.
trigger:
  tags:
    include:
    - '*'

stages:
- stage: Build
  jobs:
  - job: Build
    pool:
      vmImage: 'ubuntu-latest'

    steps:
    - script: export VERSION_TAG={{ SOMEHOW GET THE VERSION TAG HERE?? }}
      displayName: Set the git tag name as environment variable

    - script: docker-compose -f k8s/docker-compose.yml build
      displayName: 'Build docker containers'

    - script: docker-compose -f k8s/docker-compose.yml push
      displayName: 'Push docker containers'

And the docker-compose file I am referencing something like this:

version: '3'
services:
  service1:
    image: my.privaterepo.example/app/service1:${VERSION_TAG}
    build:
      [ ... REDACTED ]
  service2:
    image: my.privaterepo.example/app/service2:${VERSION_TAG}
    build:
      [ ... REDACTED ]

As you can see, the tag name in the docker-compose file is taken from the environment variable VERSION_TAG. In the YAML pipeline, I am trying to set the environment variable VERSION_TAG based on the current GIT tag. So... how do I get the name of the tag?

Answer 1

Ok, this was a bit trickier than I expected. Here's the step required to set the variable:

steps:
    - script: VERSION_TAG=`git describe --tags` && echo "##vso[task.setvariable variable=VERSION_TAG]$VERSION_TAG"
      displayName: Set the tag name as an environment variable

This script sets the variable VERSION_TAG to the name of the latest git tag. It does so in three steps:

1: git describe --tags

Prints the name of the current/latest tag

2: VERSION_TAG=`...`

Sets the output of step 1 to a local variable

3: echo "##vso[task.setvariable variable=VERSION_TAG]$VERSION_TAG"

Prints out a command that sets the variable in Azure Devops. The local variable set in step 2 is used as the value.