Relative path for module prefix

[denis256]

Description

Included changes:

• Add setting of relative path for modules / absolute path for app

Fixes #2529.

TODOs

Read the Gruntwork contribution guidelines.

• Update the docs.
• Run the relevant tests successfully, including pre-commit checks.
• Ensure any 3rd party code adheres with our license policy or delete this line if its not applicable.
• Include release notes. If this PR is backward incompatible, include a migration guide.

Release Notes (draft)

Added / Removed / Updated [X].

Migration Guide

[denis256]

Example output:

INFO[0000] The stack at /home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app will be processed in the following order for command init:
Group 1
- Module /home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/dependency

Group 2
- Module /home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app
 
[../dependency] 
[../dependency] Initializing the backend...
[../dependency] 
[../dependency] Initializing provider plugins...
[../dependency] 
[../dependency] Terraform has been successfully initialized!
[../dependency] 
[../dependency] You may now begin working with Terraform. Try running "terraform plan" to see
[../dependency] any changes that are required for your infrastructure. All Terraform commands
[../dependency] should now work.
[../dependency] 
[../dependency] If you ever set or change modules or backend configuration for Terraform,
[../dependency] rerun this command to reinitialize your working directory. If you forget, other
[../dependency] commands will detect it and remind you to do so if necessary.
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] 
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] Initializing the backend...
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] 
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] Initializing provider plugins...
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] 
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] Terraform has been successfully initialized!
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] 
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] You may now begin working with Terraform. Try running "terraform plan" to see
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] any changes that are required for your infrastructure. All Terraform commands
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] should now work.
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] 
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] If you ever set or change modules or backend configuration for Terraform,
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] rerun this command to reinitialize your working directory. If you forget, other
[/home/denis/projects/gruntwork/terragrunt/test/fixture-include-parent/app] commands will detect it and remind you to do so if necessary.

[maunzCache]

Edit: Just noticed this PR was in draft mode after spending an hour on it. Sorry if that comment came to early.

I was thinking about this part real hard because i thought there was another way and dug through some go implementation and came up with this:

Suggested change

	prefix := modulePath
	workingDirPath := terragruntOptions.WorkingDir
	// try to convert working dir to absolute path
	if path, err := filepath.Abs(workingDirPath); err == nil {
	workingDirPath = path
	}
	if workingDirPath != modulePath {
	// try to generate relative path to module to be used as prefix
	if relativePrefix, err := filepath.Rel(workingDirPath, modulePath); err == nil {
	prefix = relativePrefix
	}
	}
	opts.OutputPrefix = fmt.Sprintf("[%v] ", prefix)
	// try to convert working dir to absolute path
	absoluteWorkingDirPath, err := filepath.Abs(terragruntOptions.WorkingDir); error != nil {
	return _, err
	}
	modulePathPrefix := modulePath
	if absoluteWorkingDirPath != modulePathPrefix {
	// try to generate relative path to module to be used as prefix
	modulePathPrefix, err = filepath.Rel(absoluteWorkingDirPath, modulePathPrefix); error != nil {
	return _, err
	}
	}
	opts.OutputPrefix = fmt.Sprintf("[%v] ", modulePathPrefix)

Let's go through this:

1. The prefix var doesn't matter until later so move that down.
2. If filepath.Abs or filepath.Rel errors, this happens on a system level or the input was garbage to begin with. Simply call it directly and pass the error
3. prefix and modulePath should not differ during the runtime so pass it directly.

Also renamed the variables. Ignored it if its too verbose.

Note: I have not scrolled through the whole function so returning _ on error might be wrong.

So what do you think? I know it is a simple piece of code and i don't want to argue. Just exchanging thoughts.