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Azure batch run task with container image through az cli and json rest api

Azure Batch can be a great tool for instant batch processing as it creates and manages a pool of compute nodes (virtual machines), installs the applications you want to run, and schedules jobs to run on the nodes. The important thing using this service is that there is no additional charge for using Batch. You only pay for the underlying resources consumed, such as the virtual machines, storage, and networking.

Azure Batch documentation – Azure Batch | Microsoft Learn

In this post I will demonstrate how one can create a new job and task from az cli for batch service. The trick in this implementation will be the json that is provided as input for the task definition as not all available options are provided from az cli.

The available az cli options are shown below.

One important missing configuration will be the container image that can be provided in the task trough Azure portal but not with az cli.

In order to create a task using az cli and bypass this issue, you can use the json-file parameter. This option will trigger the creation using the rest api and provide the parameters for the container image.

When there is a batch service pool available, you will need to create a job.

az batch account login -g RESOURCE_GROUP -n NAME
az batch job create --id JOB_NAME --pool-id POOL_NAME

Then you can create a new task using a json file.

az batch task create --job-id JOB_NAME --json-file

Task – Add – REST API (Azure Batch Service) | Microsoft Learn

The JSON file can be created as shown below.

  "id": "azcli-task",
  "displayName": "azcli-task",
  "commandLine": "azcli-task",
  "containerSettings": {
    "containerRunOptions": "--rm --workdir /app",
    "imageName": ""

When you execute the command you will get an output from the rest API for the created task.

output omitted

Finally you can find the new created task on Azure portal.

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Authenticate to Azure management API using az cli

A quick an easy way to authenticate on Azure management API is to use az cli get-access-token command and use this as a Bearer token on your API calls.

Given that you want to access you can use:

$token =  az account get-access-token | ConvertFrom-Json

You can then get the access token with $token.accesstoken

Finally you can use this token as a Bearer token on your API calls

$headers = @{ Authorization = "Bearer $token.accesstoken" }
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Update variable group using Azure DevOps rest API – pipeline example

Following my previous article about how to update a variable group using POSTMAN, I will now document how to implement the same behavior through a pipeline.

First things first you will need a PAT. I have included this PAT in a different variable group than the one that I will update. this is because when you update the variable group, all the variables that are inside will get lost. If you need to retain them, you should have to get them first and then add them again on the variable group.

For this reason I have created a variable group named token-group which holds my PAT. I also made this variable a secret.

The variable group that I will update has the name of var-group and the id of 5.

The pipeline includes two tasks. The first task will loop through the variables on the group and print them out. The second task will update the variable group based on the JSON that you provided. You should change your ORG and project URLs.

– none
pr: none
vmImage: ubuntu-latest
– group: token-group
– task: PowerShell@2
displayName: Get variables from variable-group
targetType: 'inline'
script: |
$base64AuthInfo= [System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes(":$($connectionToken)"))
$URL = ""
$Result = Invoke-RestMethod -Uri $URL -Headers @{authorization = "Basic $base64AuthInfo"} -Method Get
$Variable = $Result.value.variables | ConvertTo-Json -Depth 100
Write-Host $Variable
– task: PowerShell@2
displayName: add variables on variable-group
targetType: 'inline'
script: |
$base64AuthInfo= [System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes(":$($connectionToken)"))
$URL = ""
$body = '{"id":5,"type":"Vsts","name":"var-group","variables":{"rest-var1":{"isSecret":false,"value":"rest-var-value-1"},"rest-var2":{"isSecret":false,"value":"rest-var-value-2"},"rest-var3":{"isSecret":false,"value":"rest-var-value-3"}}}'
$Result = Invoke-RestMethod -Uri $URL -Headers @{authorization = "Basic $base64AuthInfo"} -Method Put -Body $body -ContentType "application/json"
$Variable = $Result.value.variables | ConvertTo-Json -Depth 100
Write-Host $Variable

After running the pipeline you will notice a null output on the update of the variable group. This is the requested result and as task has not failed your var group will get updated.

Variables inside json

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Update variable group using Azure DevOps rest API – POSTMAN

I was struggling to update a variable group using the Azure DevOps Rest API. In this article I will document the procedure using POSTMAN.

First things first you should create a PAT in order to interact with the API. If you do not know how to create such a thing you should read my previous article about running a build through a REST api on which I documented also the creation of a PAT.

Then you will need to add the access token under authorization tab of POSTMAN using Type Basic Auth. The PAT should be added as plain text.

Then you will need to add Content-Type as application/json under Headers.

Then you will have to create your URL. This should be of the format:

Important: You should use the version=5.1-preview.1. If you use the latest version you will notice an error on the call. This is a bug that has not been fixed as I found online.

In my example I wanted to update the variable group with the ID 5 and add a variable named new-var. The body of your request should be like below. Keep in mind that we use the PUT HTTP verb to update the variable group. This means everything that is inside the variable group will be discarded. If you followed all the steps correctly you will notice the below output JSON. This should indicate success on the procedure.

Lastly you can locate your new variable inside the variable group.

Variablegroups – Update – REST API (Azure DevOps Task Agent) | Microsoft Docs

Video tutorial on YouTube: