Brittle Workflow for Generated Providers File

[skorfmann]

The process of writing the providers.tf.json file is a bit brittle.

• The Terraform version constraint is written on cdktf get
• The actual provider config is merged on cdktf synth

This breaks, when a user removes the synthesize target folder (e.g. dist). On the next synth, the provider config is still written, but the version constraints are lost.

On the other hand, when doing another cdktf get, the providers.tf.json is overwritten and leaves the dist folder in an invalid state. In order to run a cdktf get successfully, the dist folder has to be deleted.

Example

{
  "//": "generated from `cdktf get`",
  "terraform": {
    "required_providers": {
      "aws": "~> 2.0"
    }
  },
  "//": "generated from `cdktf synth`",
  "provider": {
    "aws": [
      {
        "region": "eu-central-1",
        "ignore_tags": [
          {
            "keys": [
              "foo"
            ]
          }
        ]
      }
    ]
  }
}

Possible Solution 1:

• Perform cdktf get in a temporary folder
• Write some kind of lock file for exact provider and module versions in project root directory
• Generate version constraints on synth from that lock file.

This would make sure, that the provider / module classes are always matching the source they were generated from. An upgrade would be an explicit run of cdktf get, which would regenerated the lock file.

Example

Given the following cdktf.json file:

{
  "language": "python",
  "app": "pipenv run ./main.py",
  "terraformProviders": ["aws@~> 2.0"],
  "output": "imports"
}

This could generated the following cdktf.lock file

{
  "providers": {
    "aws": {
      "version": "2.59.0"
    }
  },
  "modules": {}
}

Possible Solution 2:

Go with the approach described in #43 and make each resource (including providers) aware of the version they were generated from. Use this version information to generate the correct Terraform provider version constraints.

References

This is loosely related to #43

[skorfmann]

As discussed yesterday, we'll go with a simpler approach for now:

• Perform provider download in a temporary directory
• Write terraform.tf.json configuration in the codeMakerOutput directory root
• Copy this file into output directory during synth

[github-actions]

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