Update documentation to be explicit about cron format in each case

[mabbott-aurorasolar]

There are some places in the config where the AWS Cron format is required, because that value is going to be passed directly into AWS. That's reasonable.

There are some places - like the idle workers config - where the schedule needs to use the standard cron format. And that's also reasonable because why on earth wouldn't everyone (cough AWS cough) use the standard format?

The trouble is that is isn't very well documented which format needs to be used in every place.

This issue requests that we update the documentation to be explicit. You must use the AWS format here, you must use the standard format there, etc, ideally with links to the right way to do it.

It's not a big deal. It's just a nice to have to avoid a small foot-gun situation that caused my team some problems briefly.

If I can find some time I'll draft up a PR that does that for the docs.

[npalm]

Thx for creating this issue, this open source project is maintained on best effort. So would great if you have tim to chime in with a PR to improve the docs. You are right that 2 type of crons are used

• The cron expression leading to a task scheduler on the aws event bridge. Here an example of the cos, and it

  terraform-aws-github-runner/variables.tf

  Line 733 in 587ae5d

  description = "The configuration for updating the pool. The `pool_size` to adjust to by the events triggered by the `schedule_expression`. For example you can configure a cron expression for weekdays to adjust the pool to 10 and another expression for the weekend to adjust the pool to 1. Use `schedule_expression_timezone` to override the schedule time zone (defaults to UTC)."

• And the idle config which is uded by the lambda for scaling down to decie what to keep, See here the extensive documentation https://github-aws-runners.github.io/terraform-aws-github-runner/configuration/#idle-runners

I think a simple improvement woudl be to link in the terraform docs to either aws docs or the docs page of the module with the required details. Secondly validation rules could be added in terraform.