rich parameters: import values from legacy parameters

[mtojek]

The idea here is to import values from legacy parameters to make the migration smoother. coder_parameters should use the matching value of a legacy parameter before switching to default.

@kylecarbs has an idea to introduce legacy_variable_name or legacy_name to mark the legacy name.

[mtojek]

Hey @bpmct! The legacy_variable should be present in the v0.6.16 release of terraform-provider-coder (baking now). I think that you can try to migrate some old template (if you have a candidate) 👍

[mtojek]

Reopening as I found this buggy, need more time to spend on this

[mtojek]

Related: coder/terraform-provider-coder#109 (review)

Ok, I've done more research. Unfortunately, this PR is insufficient, and we also need to sneak the legacy_parameter_name property for migration purposes.

The legacy_variable property works well with targetting the default value, but if only we need to switch from the old parameter to coder_parameter (strip reference to a legacy variable), the coder_parameter loses context, and takes the default. This is due to the fact that we pass all build parameter values externally, and there is no mechanism/logic to pull the legacy variable value.

[mtojek]

cc @kylecarbs if you have any alternative idea how to approach this problem ^

[kylecarbs]

No additional thoughts, the above makes sense. I think it's fine to have the legacy_parameter_name property in for now, it makes a lot of sense for users.