cdktf deploy does not respect `--output` directory for `.terraform/terraform.tfstate`

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cdktf & Language Versions

cdktf v0.10.1 Python 3.9.12

Affected Resource(s)

When running cdktf deploy --output=/deployed/deployed_cdktf_state from /tmp

The synthesized cdk.tf.json ends up containing:

"backend": {
      "local": {
        "path": "/tmp/terraform.stack-name.tfstate"
      }
    },

…and saves the tfstate there (/tmp/terraform.stack-name.tfstate) on deployment - which is surprising.

Expected Behavior

Expected /tmp/terraform.stack-name.tfstate to be at /deployed/deployed_cdktf_state/terraform.stack-name.tfstate instead.

Surprisingly /deployed/deployed_cdktf_state/stacks/stack-name/.terraform/terraform.tfstate is created under the stated --output directory (/deployed/deployed_cdktf_state) but it too contains:

"backend": {
    "type": "local",
    "config": {
        "path": "/tmp/terraform.stack-name.tfstate",
        "workspace_dir": null
    },
},

1. Is there a way to explicitly use a different directory for terraform.stack-name.tfstate?
2. Is this a bug or expected?

[ansgarm]

Hi @gc-ss, you don’t have to use another backend provider, you could also explictly add a LocalBackend yourself. However, it is currently not possible to pass any configuration to the LocalBackend that is automatically added in case no backend was defined explicitly.

If you don’t want to configure the backend explicitly in every stack, you could subclass the TerraformStack class and use that new stack class for all your stacks. That stack could then add a correctly configured LocalBackend for example in its constructor. Another option would be to use an Aspect that adds the required LocalBackend.

[DanielMSchmidt]

You would do

class LocalBackendTerraformStack(
    TerraformStack,
):
   def __init__(
        self, scope: Construct, stack_name: str, *, tfstate_file_name="deployed_cdktf_state.tfstate"
    ):
        super().__init__(scope, stack_name)
       LocalBackend(scope=self,
            # Path where the state file is stored. defaults to terraform.${stackId}.tfstate
            path=pathlib.Path(scope.outdir).joinpath(tfstate_file_name).absolute().as_posix(),
            # workspace_dir="/usr/src/generic/deployed/",
        )

We don’t need to override the local backend, it’s only added if you don’t have one configured for your stack. As for the output directory, I disagree with the notion that it should be taken into consideration. More often than not the output directory is in the gitignore (like in all our templates), because if you don’t have a strong reason you don’t want to commit the HCL JSON files. If we change it like you propose this would mean we ignore the state file. Plus this folder gets cleaned by us, e.g. if you delete a stack, again making you loose your state.