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Downloading individual files from an Azure DevOps pipeline artifact using the REST API

Downloading individual files from an Azure DevOps pipeline artifact using the REST API

October 7, 2023

If you’ve come here, you know what you want. You want to be able to download individual files from an Azure DevOps pipeline artifact. The documentation makes no sense. So lets get straight to the point.

First, I want to point out that this only works with PublishPipelineArtifact, and NOT with PublishBuildArtifacts

I’ve created a demo pipeline for this post. It simply creates two text files and publishes them as a pipeline artifact.

pool:
  vmImage: 'ubuntu-latest'

steps:
  - pwsh: |
      Write-Host "Test files"
      "Test string 1" | Out-File -FilePath .\test1.txt
      "Test string 2" | Out-File -FilePath .\test2.txt      
    workingDirectory: $(Build.ArtifactStagingDirectory)

  - task: PublishPipelineArtifact@1
    inputs:
      ArtifactName: TestArtifact
      targetPath: $(Build.ArtifactStagingDirectory)

Let us start by hitting the Artifacts - Get Artifact so we can get some info about the artifact.

Request

https://dev.azure.com/oswaldtechnologies/add3132d-b1ce-4519-8299-4e67eecad1f5/_apis/build/builds/703/artifacts?artifactName=TestArtifact

Response

{
    "id": 322,
    "name": "TestArtifact",
    "source": "12f1170f-54f2-53f3-20dd-22fc7dff55f9",
    "resource": {
        "type": "PipelineArtifact",
        "data": "973C2055701973A0FDFB695031EE3F9E7A91741016CA639E9D21ECCD1B387E9B01",
        "properties": {
            "RootId": "DC04A61FBB2E879A10EE8BA01B28B4623140546805A968AB2B491B2EE1BD2E4102",
            "artifactsize": "28",
            "HashType": "DEDUPNODEORCHUNK"
        },
        "url": "https://dev.azure.com/oswaldtechnologies/add3132d-b1ce-4519-8299-4e67eecad1f5/_apis/build/builds/703/artifacts?artifactName=TestArtifact&api-version=7.1",
        "downloadUrl": "https://artprodeus21.artifacts.visualstudio.com/A3e090689-466b-408e-a12e-87c169eff347/add3132d-b1ce-4519-8299-4e67eecad1f5/_apis/artifact/cGlwZWxpbmVhcnRpZmFjdDovL29zd2FsZHRlY2hub2xvZ2llcy9wcm9qZWN0SWQvYWRkMzEzMmQtYjFjZS00NTE5LTgyOTktNGU2N2VlY2FkMWY1L2J1aWxkSWQvNzAzL2FydGlmYWN0TmFtZS9UZXN0QXJ0aWZhY3Q1/content?format=zip"
    }
}

Notice resource.data. This is actually the fileId. And this is what the documentation does not mention. We use the fileId of the actual artifact, to get the artifacts manifest contents. The manifest contains an array of all items in the artifact, including their file path and file id. So now lets hit Aritfacts - Get File with the artifacts file id to get the manifest. Oddly, you must add fileId and fileName to the query, even though what you set fileName to doesn’t matter. For this example, I’m going to call it manifest.json, because well, that’s what it is.

Request

https://dev.azure.com/oswaldtechnologies/add3132d-b1ce-4519-8299-4e67eecad1f5/_apis/build/builds/703/artifacts?artifactName=TestArtifact&fileId=973C2055701973A0FDFB695031EE3F9E7A91741016CA639E9D21ECCD1B387E9B01&fileName=manifest.json

Response

{
    "manifestFormat": "1.1.0",
    "items": [
        {
            "path": "/test1.txt",
            "blob": {
                "id": "D21C967E56201F344B44EE00F537263C3503AEB13931F99754F9E78E14E6C90C01",
                "size": 14
            }
        },
        {
            "path": "/test2.txt",
            "blob": {
                "id": "FE2A48E456C37C7BAF1F86D724E2C2B30658AA1A899201D61E23CE59A333A63801",
                "size": 14
            }
        }
    ],
    "manifestReferences": []
}

Now we can hit Aritfacts - Get File once more. This time let us get the contents of test1.txt. Again, it does not matter what you set fileName too, as long as the fileId matches the blob.id of the file you want to download.

Request

https://dev.azure.com/oswaldtechnologies/add3132d-b1ce-4519-8299-4e67eecad1f5/_apis/build/builds/703/artifacts?artifactName=TestArtifact&fileId=D21C967E56201F344B44EE00F537263C3503AEB13931F99754F9E78E14E6C90C01&fileName=test1.txt

Response

Test string 1

And there you have it! Figuring out how to do this was important for a project I was working on. I needed to download a small json file from artifacts that were over 10GB in size. It would be silly to download the whole artifact just to extract a small json file from it.

Give credit where credit is due. I found the solution to this problem via this GitHub issues comment.

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