As our terraform configurations get more complex and require more providers, it can become a stumbling block to get people to properly declare all of the providers needed for their configuration. I noticed an increasing waste of cycles on just this issue, especially with newer users trying to use terraform in our organization.
To help alleviate this frustration, I decided that it would be easier to enforce a standard set of provider aliases than to get users to use the correct provider configuration for a given environment/situation. I started to think how terragrunt ccould help with this and the generate block seemed the best candidate. I found that I had to combine this with run_cmd() to download the script at runtime so I didn’t have to keep an updated script in every terraform repository that I have.
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Providers have been declared in main.tf previously. You can easily tweak the check for this if your environment is different.
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Credentials needed by providers are provided in environment variables.
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The following environment variables are available (I run terraform/terragrunt through atlantis, so they are):
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GITHUB_BASE_URL
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BASE_REPO_OWNER
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BASE_REPO_NAME
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You still have to declare a required_providers block.
The issue is that if someone chooses to use a provider not supported by this script for automagic configuration, there is no way for them to inject the provider into required_providers - there can be only one of those blocks.