Use relative paths for archives

[raymondbutcher]

what

• Avoid using absolute paths which are not portable across workstations

why

This fixes issues when multiple people are working on the same project and they have the project located in different places.

Before this change, we were seeing plans like:

  ~ module.lambda_ami_backup.aws_lambda_function.ami_backup
      filename:                    "/home/user1/some-project/terraform/workspace/management-nonprod/.terraform/modules/49890e3df5623d30b47ac70e1936d38f/ami_backup.zip" => "/Users/user2/some-project/terraform/workspace/management-nonprod/.terraform/modules/49890e3df5623d30b47ac70e1936d38f/ami_backup.zip"

We've tested this change and the plans are now clean.

I've used relative paths like this in other modules/projects, putting archives in the .terraform directory, and haven't had any issues so far. An md5 is used in the filename to avoid conflicts with multiple versions of this module being used in the same project (unlikely but it's better to be safe).

[osterman]

@raymondbutcher thanks for this fix! Makes sense. This was a bug =)

[osterman]

I'm concerned with the portability of hardcoding both .terraform and the module name terraform-aws-ec2-ami-backup which is subject to change in forks.

I propose the following:

• create a new variable called tfstate_dir and default it to .terraform
• use a local called module_name which is derived from basename(path.module)
• use a local to define an output_dir which is equal to ${tfstate_dir}/${module_name}

[osterman]

This is also a nice fix: hashicorp/terraform#8204 (comment)

Take your pick =)

[osterman]

See inline comments.

[raymondbutcher]

Thanks @osterman, fair points.

I've done a (nicer IMO) variation of hashicorp/terraform#8204 (comment) that was suggested and this is the resulting plan:

  ~ module.lambda_ami_backup.aws_lambda_function.ami_backup
      filename: ".terraform/terraform-aws-ec2-ami-backup/backup-66f40c060f29561cb074987a03c45117.zip" => ".terraform/modules/49890e3df5623d30b47ac70e1936d38f/ami_backup.zip"

  ~ module.lambda_ami_backup.aws_lambda_function.ami_cleanup
      filename: ".terraform/terraform-aws-ec2-ami-backup/cleanup-ff78a3eaea904d4807a069837535acc0.zip" => ".terraform/modules/49890e3df5623d30b47ac70e1936d38f/ami_cleanup.zip"

As per my commit message:

This removes the assumption about Terraform making a .terraform directory in the current working directory, and removes the need to use md5 to handle multiple module versions in the same project as Terraform deals with that itself. It now assumes that the module is located within the current working directory.

I think it's safe to assume that. hashicorp/terraform#8204 (comment) makes the same assumption.

[osterman]

We have one other PR we should merge before this one. We will take care of this today.