How to select agent pool dynamically on running a pipeline using restapi

Question

I want to select the agent pool while I run the pipeline using restapi call, Is it possible ? if yes can you share the request structure and the sample pipeline yaml also the restAPI URL

Answer 1

modify your Azure DevOps YAML pipeline to accept a parameter

parameters:
  - name: agentName
    displayName: Agent Name
    type: string
    default: 'DefaultPool'

pool:
  ${{ if eq(parameters.agentName, 'DefaultPool') }}:
    name: DefaultPool
  ${{ if ne(parameters.agentName, 'DefaultPool') }}:
    name: ${{ parameters.agentName }}

The REST API endpoint to trigger a pipeline is

POST https://dev.azure.com/{organization}/{project}/_apis/pipelines/{pipelineId}/runs?api-version=7.1-preview.1

https://learn.microsoft.com/en-us/rest/api/azure/devops/pipelines/runs/run-pipeline?view=azure-devops-rest-7.1

The request body should include the parameter

{
    "templateParameters": {
        "agentName": "CustomAgentPool"
    }
}

API call to trigger the pipeline

const AZURE_PIPELINE_URL = 'https://dev.azure.com/{organization}/{project}/_apis/pipelines/{pipelineId}/runs?api-version=7.1-preview.1';

fetch(AZURE_PIPELINE_URL, {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'Authorization': 'Basic ' + AZURE_PERSONAL_ACCESS_TOKEN,
  },
  body: JSON.stringify({
    templateParameters: {
      agentName: 'CustomAgentPool'
    }
  }),
})

Answer 2

It is giving an error

{
    "$id": "1",
    "innerException": null,
    "message": "/got-RapidDev.yaml (Line: 11, Col: 8): A template expression is not allowed in this context",
    "typeName": "Microsoft.Azure.Pipelines.WebApi.PipelineValidationException, Microsoft.Azure.Pipelines.WebApi",
    "typeKey": "PipelineValidationException",
    "errorCode": 0,
    "eventId": 3000
}