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scottwinkler / terraform-provider-shell

Terraform provider for executing shell commands and saving output to state file
Mozilla Public License 2.0
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Track exit code returned by the script #35

Closed lawrencegripper closed 4 years ago

lawrencegripper commented 4 years ago

Hi,

Would you be happy for me to put together a PR to track the exit codes coming back from the scripts?

The use case here is to prevent additional calls to scripts when a failure occurs. Currently I think what will happen (based on what I've seen) is that if read will exit with non-zero code and not output any state (say a network issue has prevented a curl call) the provider does a diff with the current state and observes a change, to rectify this it calls update. My expectation would be to have the error cause the terraform apply to terminate instead and let the user review the error then re-run as needed.

This change would mean that scripts should always return a 0 exit code if they want their state output to be persisted or a non-zero code if they want to terminate and display the error.

An added bonus here is that we'd be able to take the cmd output from the error'd script and return it to Terraform so it'd displayed to the user without setting TF_LOG=debug (would only happen when the script error'd but still useful).

I think I need to change this section:

https://github.com/scottwinkler/terraform-provider-shell/blob/a605c7b5edf970a7428c2f832686355782a7893e/shell/utility.go#L100-L108

To use a pattern like this:

https://stackoverflow.com/a/10385867/3437018

Sound like a useful change?

scottwinkler commented 4 years ago

Yes that sounds like a good feature to add. Better error handling is always nice. I didnt add this before because errors happening arent necessarily a problem, but you are right that if the script exists with a nonzero condition then its probably worth throwing a hard error at that point.

Another thing that would be welcome is more and better tests. Could you also add at least one test for this new feature?

lawrencegripper commented 4 years ago

Looked pretty easy to get done so I've submitted a PR, didn't need to get the exact exit code as turns out the exec package returns an error on non-zero codes.

Got some output back to the user too for debugging without TF_LOG=debug

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Added a test to validate that an error is returned correctly too :)

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