Azure Pipeline Task inputs won't accept variables

Question

In the azure pipeline yaml files, the variable imgRepoName is trimmed from the gitRepoName. An bash echo for gitRepoName shown core/cqb-api; bash echo for imgRepoName shown cqb-api

variables:
  vmImageName: 'ubuntu-18.04'
  gitRepoName: $(Build.Repository.Name)
  imgRepoName: $(basename $(gitRepoName))

  - job: build_push_image
    pool:
      vmImage: $(vmImageName)
    steps:
      - task: Docker@2
        displayName: Build and Push image
        inputs:
          repository: imgRepoName
          command: buildAndPush
          containerRegistry: "coreContainerRegistry"
          tags: test2

Issues:

When I wrote repository: "cqb-api" as the input for the docker task it works just fine, while use the variable directly as shown above won't create any images in the container registry.

PS, I also tried repository: $(imgRepoName) it give out the following error

invalid argument "***/$(basenamecore/cqb-api):test2" for "-t, --tag" flag: invalid reference format

Answer 1

It looks that it is executed at runtime. So gitreponame is replaced but basename function is not recognized in this context. You can check this:

variables:
  gitRepoName: $(Build.Repository.Name)

steps:
- task: PowerShell@2
  inputs:
    targetType: 'inline'
    script: |
        $name = $(basename $(gitRepoName))
        Write-Host "##vso[task.setvariable variable=imgRepoName]$name"

- task: Docker@2
  displayName: Build and Push
  inputs:
    repository: $(imgRepoName)
    command: build
    Dockerfile: docker-multiple-apps/Dockerfile
    tags: |
      build-on-agent

It works for me.