Provision a VSTS Agent using an ARM Linux Custom Script Extension

There are many ways to get VSTS Agents deployed to a machine. You can find more on that here: In this post you will find a way to deploy a VSTS Agent on a Linux Azure VM through an ARM template. For this we use a Custom Script Extension.

I intentionally left out the creation of the Linux VM in this post. I used a Packer script for this while my collegue Manuel Riezebosch created a very convenient VSTS Task for that! See this here:

To deploy the agent a couple of steps are involved;

  1. Get the download URL for the agent; blogged here:
  2. Encode a Linux script, to install the agent
  3. Use a Linux ARM Custom Script Extension in your ARM template

To create the encoded script I used another Inline PowerShell Task in VSTS. The full script can be found here:

To clarify the details I expanded the script a bit:

1. curl -s $(AgentDownloadUrl) > /tmp/agent.tar.gz;
2. for i in `seq 1 $(AgentsPerVM)`;
3. do mkdir /agent$i &&
4. cd /agent$i &&
5. tar zxf /tmp/agent.tar.gz -C . &&
6. chmod -R 777 . &&
7. sudo -u $(AdminUserName) ./ --unattended --url $(VSTSAccount) --auth pat --token $(PersonalAccessToken) --pool $(AgentPool) --agent $(AgentName)$i --work ./_work --runAsService &&
8. ./ install &&
9. ./ start;
10. done;

The following lines comment the script above on line by line basis;
1. Download the VSTS Agent, save in the tmp folder
2. Loop for the desired number of agents
3. Create the agent directory
4. Go to agent specific directory
5. Unpack the agent in folder
6. Set permissions for the directory so that users can access it
7. For the user, configure the agent for to the specified VSTS account, using a PAT and named Pool and provided Agent name.
8. During the configuration a file is generated. This needs to be run to install the service.
9. After installation the service can be started using the start method.
10. Done one loop

This script needs to be passed to the ARM template. The Custom Script Extension allows us to send a base64 encoded script. So we encrypt the script first and then encode it.

$Bytes = [System.Text.Encoding]::UTF8.GetBytes($script)
$EncodedText =[Convert]::ToBase64String($Bytes)

The encoded script is stored in a VSTS Variable

Write-Host "##vso[task.setvariable variable=EncodedScript;issecret=true]$EncodedText"

This script can be passed to a section in an ARM template through a parameter for the ARM template. The template can be deployed using the Azure Resource Group Deployment task.

In the ARM template you can add a section that executes the provided script. The section can be found here:

More details on the current Custom Script Extensions can be found here: and here:


Getting the latest VSTS Agent Download URL for your account

This week I have been playing to automatically provision a VSTS Agent on a Linux Machine. One thing i noticed is that in separate VSTS accounts the latest agent is not always the agent your account supports.

There may be little risk but this PowerShell script, that I use in an Inline PowerShell script in a Task during my provisioning release, helps to get the URL for the account your are targeting. Convenient and checked.

The script requires a few parameters;

  • PersonalAccesToken – A PAT for the VSTS account you are targeting
  • VSTSAccount – The url
  • AgentType – The REST API calls for the Agent Type requested, this could be one of three values; “linux-x64”, “windows-x64” or “osx-x64”

The script updates a variable, AgentDownloadUrl, that can be used in the pipeline.

View/Download the script here:



Adding a Team Administrator through the VSTS Rest API

In many projects I come across there is a desire to add a Team Administrator to a VSTS Project. While there is allot of quality documentation, there is no clear route to add a Team Administator to a VSTS Project.

I investigated what calls the VSTS Web UI makes to add a team administrator and constructed a script that does exactly that.

The UI uses a simple method call this method: where it posts a piece of JSON. This basically consists of the Team ID and the user that you want to add.

However to construct this message you need to do several calls to get the required information. It involves getting all the Groups, Users and the users StorageKey to be able to add the administrator.

I created a script containing all the methods and supportive functions that can be found in my GitHub account here: