Terraform Cloud Variables Are All Strings

This post easily falls into the “so ridiculous that it shouldn’t be a post” category. However, considering how long I ended up stuck on it earlier today, I figure it’s worth making if it stands a chance of helping even one other person avoid the same fate as me. 😅

I’ve started doing a little bit of work with the Terraform Cloud API. Specifically, I was looking at being able to update a workspace variable through code. In this case, I was trying to change a variable I called replica_count which, if the name wasn't enough of a giveaway, I was using to track how many replicas should be used in a Kubernetes container spec.

I found that I was able to easily get back all of my workspace variables via a GET to:

https://app.terraform.io/api/v2/workspaces/{workspace_id}/vars/

However, trying to make a PATCH to...

https://app.terraform.io/api/v2/workspaces/{workspace_id}/vars/{variable_id}

… with a body in JSON to specify the change resulted in a 500 internal server error response.

The JSON in the body wasn’t very complex. I only needed to modify the value. As the documentation specifies, and the type must be set to "vars" and the id must be set to the ID of the variable to change. This is a bit odd to me since I also have to give the ID in the URL, but it's not a big deal. The attributes property then can optionally contain whatever property or properties need to be updated. In my case, the JSON just looked like:

{
“data”: {
“id”: var_id,
“type”: “vars”,
“attributes”: {
“value”: 2
}
}
}

There isn’t a lot to go wrong here… but I managed to do it! I finally figured out what was wrong when I changed my PATCH to a GET just to validate that my JSON had to be the culprit. The GET responds with JSON which is very similar to what I needed to send, and that's what tipped me off to the fact that the value of the variable is always a string, even if I'm thinking of it as a number in my head. So my value line needed to be:

"value": "2"

After seeing that in the response to my GET, I updated my JSON, re- PATCH ed, and saw that everything was successful.

Originally published at https://blog.looped.network on July 25, 2022.

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