Output variables to use between Pipeline tasks in Azure DevOps

Let’s see how we can output a variable with a value that is the result of an operation of a task to another task on Azure Devops

To put it in context, let’s say we want to retrieve an access token from an Azure CLI task, and then use that another task which executes an .NET App which performs a certain operation and needs access to a Key Vault. Obviously, this procedure of passing a variable output from a task to another has lot of uses, but this is the example (taken from a real situation) that I chose.

First of all, go to Pipelines > Release Pipeline, create a new Job and add an Azure CLI task, configure the correct Azure Resource Manager connection, which should have access to the resource your app will try to connect to. Then choose a Script Type and for this example we will use an Inline script for Script Location, then we will type the following script in the Inline Script field:

sudo apt install -y jq

echo "##vso[task.setvariable variable=token;isOutput=true;]$(az account get-access-token --resource=https://vault.azure.net | jq -r .accessToken)"

Let’s see what it does:

• sudo apt install -y jq: Installs the jq package without prompting. jq is used to parse JSON, and in this case we are installing it with apt, since the Agent it is running on is Ubuntu, you may change have to modify this command. In this case we are using jq in the next command to parse the response of the az account get-access-token
• ##vso[task.setvariable variable=token;isOutput=true;]: This is used to indicate that what is being outputted by echo is going to be saved on the token variable (it is indicated by the variable=token part) and that it is an output variable (indicated by isOutput=true).
• $(az account get-access-token --resource=https://vault.azure.net | jq -r .accessToken): This command retrieves an access token, then jq parses it and outputs the raw value (because of the -r option) of the field accessToken

Then finally, in our Azure CLI task we must specify reference name for our output variable. Go to Output Variables which is at the bottom of the task, and on the Reference name field insert the name from which you will reference the variable(s) you defined in this task. In this case I will use AccessToken

Next we will use this new variable in a Bash Script task. First, we must create an environment variable using the variable outputted in the previous task: go to the Environment Variables section and add the following variable (by clicking the + Add):

Name	Value
ACCESS_TOKEN	$(AccessToken.token)

This will create an environment variable named ACCESS_TOKEN which we will be able to use from within our script as any other environment variable, and which has the value of $(AccessToken.token) variable. Here you can see that we are using our Reference Name AccessToken and accessing the variable token we defined.

Now we can use it from within our script, for instance, we can print it in an inline script:

echo $ACCESS_TOKEN

This has lot of uses and is up to you to adapt it and use it to your own convenience.