So you’re trying to use the Terraform
azurerm_function_app_host_keys resource to get the keys from an Azure function after deployment. Sadly, as of 03/2021, this can fail intermittently 😢 (See issue 1 and 2).+
[Edit: Hopefully this issue is resolved by this PR once released so worth reviewing once the change is released]
These errors can look something like these below:
Error making Read request on AzureRM Function App Hostkeys “***”: web.AppsClient#ListHostKeys: Failure responding to request: StatusCode=400 — Original Error: autorest/azure: Service returned an error. Status=400 Code=”BadRequest” Message=”Encountered an error (ServiceUnavailable) from host runtime”
Error: Error making Read request on AzureRM Function App Hostkeys “somefunx”: web.AppsClient#ListHostKeys: Failure responding to request: StatusCode=400
You can work around this by using my previous workaround with ARM templates but it’s a bit clunky so I was looking at another way to do it.
There is an AWESOME project by Scott Winkler called Shell Provider, it lets you write a custom Terraform provider using scripts. You can implement data types and full resources with CRUD support.
Looking into the errors returned by the azurerm_function_app_host_keys resource they’re intermittent and look like they’re related to a timing issue. Did you know the
curl command support retrying out of the box?
So using the Shell provider we can create a simple script to make the REST request to the Azure API and use
curls inbuilt retry support to have the request retried with an exponential back-off until it succeeds or 5mins is up!
Warning: This script uses –retry-all-errors which is only available in v7.71 and above. The version shipped with the distro your using might not be up-to-date user
curl --version to check.
Here is a rough example of what you end up with: