{"id":1251,"date":"2020-08-25T12:51:10","date_gmt":"2020-08-25T19:51:10","guid":{"rendered":"http:\/\/blog.nillsf.com\/?p=1251"},"modified":"2020-08-25T12:51:13","modified_gmt":"2020-08-25T19:51:13","slug":"how-to-use-terraform-output-in-a-github-action","status":"publish","type":"post","link":"https:\/\/nillsf.com\/index.php\/2020\/08\/25\/how-to-use-terraform-output-in-a-github-action\/","title":{"rendered":"How to use ‘terraform output’ in a GitHub action"},"content":{"rendered":"\n

Recently, I was building a GitHub Actions pipeline, and needed to access output from Terraform. There’s a very convenient feature in Terraform<\/a> that allows you to get output from your applied .tf files. You can call those values from the shell directly, and assign them to variables in your shell.<\/p>\n\n\n\n

What you need to do to define an output, and then call it from your shell is the following=:<\/p>\n\n\n\n

output \"rgname\" {\n  value = azurerm_resource_group.aks-sd-rg.name\n}<\/code><\/pre>\n\n\n\n
Which you can then call from a shell like this:<\/p>\n\n\n\n
terraform output rgname<\/code><\/pre>\n\n\n\n
And if you want to assign this to a local variable, you can do this:<\/p>\n\n\n\n
rgname=$(terraform output rgname)<\/code><\/pre>\n\n\n\n
However, when using this in a GitHub Action, this fails consistently. This can very easily be fixed in the setup of the Terraform action in your GitHub action:<\/p>\n\n\n\n
    - name: Setup Terraform\n      uses: hashicorp\/setup-terraform@v1\n      with:\n        terraform_wrapper: false<\/code><\/pre>\n\n\n\n
And with that you should be able to refer to the output correctly. Let me show you a working example of this on GitHub.<\/p>\n\n\n\n
Minimal PoC on GitHub<\/h2>\n\n\n\n
I built a very minimal PoC of this on GitHub<\/a>. A very small TF file is used to generate output:<\/p>\n\n\n\n
locals {\n    test = \"this is the output\"\n}\n\noutput test{\n    value = local.test\n}<\/code><\/pre>\n\n\n\n
And I have two actions. One without the terraform_wrapper<\/code>, one with the terraform_wrapper<\/code>. In each action, I execute the following small shell script at the end:<\/p>\n\n\n\n
output=$(terraform output test)\necho $output<\/code><\/pre>\n\n\n\n
Without the wrapper, this is the result of the Action:<\/p>\n\n\n\n
\"\"
Output of the echo $output command<\/figcaption><\/figure>\n\n\n\n
With the wrapper in place, this is the result of the Action:<\/p>\n\n\n\n
\"\"
Output of the echo $output with the wrapper=false in place.<\/figcaption><\/figure>\n\n\n\n
You can check out the full actions files I used for this here:<\/p>\n\n\n\n