Using Azure Devops Invoke REST API task in yaml

 Documentation on using the Invoke REST API Azure DevOps task is sparse so I am documenting my solution; hopefully I can spare someone some time and headaches.

First, to be clear, this task is categorized in the GUI as a gate so the Get use case is for true/falseness. This means it is not possible to access any part of the response outside of this step. Although it would be straight forward to script calling a rest method, it is appealing to have a simple step that handles all that and I just configure a condition. It is worth noting, if you don't need to parse the response then Invoke REST API post is a great way for fire and forget type messaging - like sending a teams notification.

In my scenario, I want to automate release branch creation and steps required around that in our corporate processes. Before creating the branch, I want to make sure that Master is not ahead of Develop. Ahead count is available in the Git Stats API. There is a sample response in the documentation that shows that aheadCount is a root property. 

These are the steps I followed

• Configure a generic service connection without user or password/token information.
• Create a yaml file with the stages and jobs needed. Note that this is a Server task.
• Under steps, add an Invoke REST API step, the gui gives some guidance here but remove the default headers and add an Authorization header containing "Bearer $(System.AccessToken)".
• Add the url, using system variables for simpler re-use.
• Set the success criteria to "eq(root['aheadCount'], 0)"
  
• Following jobs or tasks in the stage should have a dependsOn configured for this task or job.

The GUI interface looks like this

 

The yaml looks like this. I use a simple delay step just to test the gate quickly before adding the rest of the logic.

stages:

  - stage: Release_Branch

    displayName: Create release branch

    condition: always()

    jobs:

      - job: EntryGate

        displayName: Entry gate

        pool: Server

        steps:      

        - task: InvokeRESTAPI@1

          displayName: Check ahead count is 0

          inputs:

            connectionType: 'connectedServiceName'

            serviceConnection: 'AzureDevOpsRest'

            method: 'GET'

            headers: |

              {

              "Authorization": "Bearer $(system.AccessToken)"

              }

            urlSuffix: '/$(System.TeamProject)/_apis/git/repositories/$(Build.Repository.ID)/stats/branches?name=master&api-version=6.0'

            waitForCompletion: 'false'

            successCriteria: "eq(root['aheadCount'], 0)" 

      - job: one_min_delay

        pool: Server

        dependsOn: 

        - EntryGate

        steps:

        - task: Delay@1

          inputs:

            delayForMinutes: '1'