You can configure the pipeline to use the GitVersion tool combining with the counter function to automatically generate the expected version number.

1. Install the GitTools extension to your Azure DevOps organization. It provides the pipeline tasks to install and execute the GitVersion tool for semantic versioning.

2. In the root of your application code repository, add the GitVersion.yml file referencing the sample below.

   # GitVersion.yml
   
   mode: mainline
   tag-prefix: '[vV]?'
   assembly-informational-format: '{Major}.{Minor}.{Patch}'
   major-version-bump-message: '+semver:s?(major)'
   minor-version-bump-message: '+semver:s?(minor)'
   patch-version-bump-message: '+semver:s?(code|app)'
   no-bump-message: '+semver:s?(none|skip)'
   commit-message-incrementing: Enabled
   update-build-number: false
   

   • The {major} is the {major} in your version number.
   • The {minor} is the {minor} in your version number.
   • The {Patch} is the {codeVersion} in your version number.

3. In the root of your application code repository, add the pipeline main YAML file referencing the sample below.

   # azure-pipelines.yml
   
   # Set the CI trigger.
   trigger:
     branches:
       include:
       - main
   
   # Set the environment config repository as a repository resource.
   # And enable resource trigger.
   resources:
     repositories:
     - repository: config
       type: git
       name: envConfig
       ref: main
       trigger:
         branches:
           include:
           - main
   
   # Generate the part "{configVersion}" of the app version number.
   variables:
     configVersion: $[ counter(resources.repositories.self.version, 0) ]
   
   steps:
   - checkout: self
     fetchDepth: 0
   
   - task: gitversion/setup@3
     displayName: 'Install GitVersion'
     inputs:
       versionSpec: '5.x'
       preferLatestVersion: true
   
   # Generate the part "{major}.{minor}.{codeVersion}" of the app version number.
   # The task sets the variable "$(GitVersion.FullSemVer)" to pass the generated value.
   - task: gitversion/execute@3
     displayName: 'Generate Version'
   
   # Combine the generated values to get the full app version number.
   # Update the pipeline build/run number with the full app version number.
   - bash: |
       echo "##vso[task.setvariable variable=APP_VERSION;]$(GitVersion.FullSemVer).$(configVersion)"
       echo "##vso[build.updatebuildnumber]$(GitVersion.FullSemVer).$(configVersion)"
     displayName: 'Set App Version'
   
   - bash: |
       echo "APP_VERSION = $(APP_VERSION)"
     displayName: 'Print App Version'
   
   . . .
   

4. In the application code repository, create the tag “v0.1.0.0” to the latest commit (see “Create tags from the Commits view“).

5. Use above azure-pipelines.yml file to create a pipeline for the application code repository.

With above configurations:

• When you trigger the pipeline at the first time to run for the latest commit which has the tag “v0.1.0.0“, the generated app version number is the ‘0.1.0.0‘.

• When you push a new commit to the main branch of application code repository, the pipeline gets automatically triggered by the CI trigger. The number of ‘{codeVersion}‘ +1. For example, the full app version number changes from “v0.1.0.0” to “v0.1.1.0“.

• When you push a new commit to the main branch of application code repository, and the commit message contains the string “+semver: code” or “+semver: app“, the number of ‘{codeVersion}‘ also can +1.

• when you push a new commit to the main branch of environment config repository, the pipeline gets automatically triggered by the resource trigger. The number of ‘{configVersion}‘ +1. For example, the full app version number changes from “v0.1.1.0” to “v0.1.1.1“.

• When you push a another new commit to the main branch of application code repository, the pipeline gets automatically triggered by the CI trigger. The number of ‘{codeVersion}‘ +1, and the number of ‘{configVersion}‘ gets back to 0. For example, the full app version number changes from “v0.1.1.1” to “v0.1.2.0“.

• When you push a new commit to the main branch of application code repository, and the commit message contains the string “+semver: minor“, the number of ‘{minor}‘ +1, the numbers of ‘{codeVersion}‘ and ‘{configVersion}‘ gets back to 0.

• When you push a new commit to the main branch of application code repository, and the commit message contains the string “+semver: major“, the number of ‘{major}‘ +1, the numbers of ‘{minor}‘, ‘{codeVersion}‘ and ‘{configVersion}‘ gets back to 0.

• If no commit pushed to neither the application code repository nor the environment config repository, the pipeline will not get automatically triggered. So, no new version number generated.

EDIT:

Try to configure the pipeline like as below.

trigger:
  branches:
    include:
    - main

resources:
  repositories:
  - repository: config
    type: git
    name: envConfig
    ref: main
    trigger:
      branches:
        include:
        - main

jobs:
- ${{ if notIn(variables['Build.Reason'], 'Manual') }}:
  - job: build
    variables:
      configVersion: $[ counter(resources.repositories.self.version, 0) ]
    steps:
    - checkout: self
      fetchDepth: 0

    - task: gitversion/setup@3
      displayName: 'Install GitVersion'
      inputs:
        versionSpec: '5.x'
        preferLatestVersion: true

    - task: gitversion/execute@3
      displayName: 'Generate Version'

    - bash: |
        echo "##vso[task.setvariable variable=APP_VERSION;]$(GitVersion.FullSemVer).$(configVersion)"
        echo "##vso[build.updatebuildnumber]$(GitVersion.FullSemVer).$(configVersion)"
      displayName: 'Set App Version'

    - bash: |
        echo "APP_VERSION = $(APP_VERSION)"
      displayName: 'Print App Version'

    . . .

- ${{ else }}:
  - job: noUpdate
    steps:
    - script: |
        echo "This run is not automatically triggered by any new updates."
        echo "Skip all the build steps. Version number will not be updated."

With above configurations, if the pipeline is triggered by manual (Build.Reason = Manual), the whole build job will not run, the number of configVersion also will not increase, and the noUpdate gets run.

In the condition expression “${{ if notIn(xxxx) }}“, you can add more than one items. For example, “${{ if notIn(variables['Build.Reason'], 'Manual', 'Schedule') }}“, the build job will not run when the pipeline is triggered by manual or schedule (Build.Reason = Schedule). See the documentation “Expressions“.

The available values of Build.Reason are listed in the image below. You also can see the documentation “Use predefined variables“.