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I'm writing an Azure DevOps extension in which I'd like to create a server task to execute a couple of http requests and wait for the completion event from an external source. My problem is that the server task options are almost undocumented and so this became a guess-and-try game from my part.

I've used the following two resources to have some ideas what I can do:

Also I've checked a couple of public extensions with server tasks:

Even though there are signs in these that what I'm trying to achieve is possible, so far, none of my attempts have worked.

task.json

"execution": {
  "HttpRequestChain": {
    "Execute": [
      {
        "RequestInputs": {
          "EndpointUrl": "first-url"
          "Method": "first-method",
          "Headers": "first-headers",
          "Body": "first-body",
          "Expression": "first-condition-expression"
        },
        "ExecutionOptions": {
          "OutputVariables": "first-outputs",
          "SkipSectionExpression": "first-skip-expression"
        }
      }

      .
      .
      .

      {
        "RequestInputs": {
          "EndpointUrl": "last-url"
          "Method": "last-method",
          "Headers": "last-headers",
          "Body": "last-body",
          "Expression": "last-condition-expression"
        },
        "ExecutionOptions": {
          "OutputVariables": "last-outputs",
          "SkipSectionExpression": "last-skip-expression"
        }
      }
    ]
  }
}

First I tried to add "WaitForCompletion": "true" to the last RequestInputs section as can be seen in servertaskauthoring.md under HttpRequest and in CreateAndQueryChangeRequestV2/task.json.

It did not do anything as far as I could tell, and also found the following community question and its related Github issue which says this:

The 'waitForCompletion' option is currently not available for HttpChainRequest task by design.

So, I changed my approach and wanted to add a prejobexecution section to split my task into two parts: a preparation part and a waiting part.

"prejobexecution": {
  "HttpRequestChain": {
    "Execute": [
      {
        "RequestInputs": {
          "EndpointUrl": "first-url"
          "Method": "first-method",
          "Headers": "first-headers",
          "Body": "first-body",
          "Expression": "first-condition-expression"
        },
        "ExecutionOptions": {
          "OutputVariables": "first-outputs",
          "SkipSectionExpression": "first-skip-expression"
        }
      }

      .
      .
      .

    ]
  }
}
"execution": {
  "HttpRequest": {
    "Execute": {
      {
        "EndpointUrl": "last-url"
        "Method": "last-method",
        "Headers": "last-headers",
        "Body": "last-body",
        "Expression": "last-condition-expression",
        "WaitForCompletion": "true"
      }
    }
  }
}

In this scenario, the prejobexecution part did not show up, only the execution was added to the pipeline run. I guess the prejobexecution is not supported by server tasks, but I could not find any resource explicitly pointing this out.

Currently, I'm experimenting with two separate server tasks, one using the HttpRequestChain without wait and one using the HttpRequest with wait. I haven't tried it out yet, but regardless of the result, I feel having everything in one task is easier to use/setup and way more elegant.

Thus, I'm wondering if it is possible to achieve and if so, how. In addition it would be a huge help if anyone could share with me a complete documentation about server tasks or why my previous attempts were not successful.

Edit: adding details about the goal of the extension

I'd like to provide an easy way to stop a pipeline run at any point and ask for an approval from a specific person or member of a specific group. It'd be different

  • from the ManualValidation task, because only the selected person/people could approve, not anyone with queue builds permission, and
  • from the approvals and checks, because it could be added to any point of a pipeline run, not just to the start of a stage.

This is definitely a need at my company, but I saw similar feature requests, so I decided to develop it independetly as a public extension and upload it to the marketplace. That is why I'm trying to make it into one task only; I hope that'll make the whole extension more userfriendly, less error-phrone and easier to use overall. And since the plan is to share it with other people, converting it into a template or task group is not working for this case if my understanding is correct.

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Per your expectation to

Create a server task to execute a couple of http requests and wait for the completion event from an external source.

You may consider working this around with the Delay task, which is one of the Agentless jobs supported tasks.

Besides, the source code (task.json files) below for such tasks for your reference may help build your own extension task.

azure-pipelines-tasks/Tasks/DelayV1 at master · microsoft/azure-pipelines-tasks · GitHub;

azure-pipelines-tasks/Tasks/InvokeRestApiV1 at master · microsoft/azure-pipelines-tasks · GitHub.

Adding task.json references:

For YAML pipeline: azure-pipelines-tasks/Tasks/ManualValidationV0 at master · microsoft/azure-pipelines-tasks · GitHub

For release pipeline: azure-pipelines-tasks/Tasks/ManualInterventionV8 at master · microsoft/azure-pipelines-tasks · GitHub

As discussed, a set of above built-in server tasks defined in task group or YAML template may do the same work and can be more flexible.

Based on the further discussions, as an optional workaround as of now or a possible direction, you may leverage the Asynchronous checks of a Rest API to wait for a callback sent by your custom workflow.

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8 Comments

Thanks for your answer! Unfortunatelly the Delay task is not really an option for me, because I don't know how much the task should wait. The usual workflow would be: 1) the task's preparation is done, 2) the task starts waiting, 3) a specific user completes some action which notifies the waiting task 4) the task completes and the pipeline run continues. Kind of like the ManualValidation task, but I'd like to create a stricter, more specific version of it.
Then a set of build-in server tasks should work and more flexible right?
For classic pipelines, you can use task group and for YAML pipeline you can use templates. May I know what makes you have to create a custom extension then?
The idea is very simple, I'd like to provide an easy way to stop a pipeline run at any point and ask for an approval from a specific person or member of a specific group. It'd different from the ManualValidation task, because only the selected person/people could approve, not anyone with queue builds permission and it'd be differerent from the approvals and checks, because it could be added to any point of a pipeline run, not just to the start of a stage.
It is definitelly a need at my company, but I saw similar feature requests, so I decided to develop it independetly as a public extension and upload it to the marketplace. That is why I'm trying to make it into one task only; I hope that'll make the whole extension more userfriendly, less error-phrone and easier to use overall. And since the plan is to share it with other people, converting it into a template or task group is not working for this case if my understanding is correct.
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