Show a diff when a file will be or gets modified

[jgelens]

Now shows a diff of files which will be modified, only when its checksum its different.

Thanks @xvello (#985 (comment)) for the code!

This solves #985

• Pull request is based on the default branch (3.x at this time)
• Pull request includes tests for any new/updated operations/facts
• Pull request includes documentation for any new/updated operations/facts
• Tests pass (see scripts/dev-test.sh)
• Type checking & code style passes (see scripts/dev-lint.sh)

[jgelens]

Example output:

[jgelens]

Working on some improvements to not use `host.get_file'

[Fizzadar]

This is awesome, just noting I'm not forgetting it. Need to handle when to show/not show the diff (ie when -v). Going to get the pending stuff released and get then think on that to land this.

[jgelens]

Right, maybe it would be best to add a new flag for that. I always would like to see the diff, even when not using -v. So maybe we could add a --diff flag for this; similar to the same Ansible feature.

I was also thinking to add a global flag, which also can be used to override single operations. In case people do not want to show it for e.g. editing a file with passwords.

[xvello]

I also think it's good to show the diffs without verbose logging, that's how I currently use it. A command line switch could indeed be enough.

@jgelens thanks for pushing this over the finish line. When you're pushing other changes, would you mind adding a Co-authored-by: Xavier Vello <xavier.vello@gmail.com> line in the git commit message of the first commit, for attribution?

[jgelens]

@jgelens thanks for pushing this over the finish line. When you're pushing other changes, would you mind adding a Co-authored-by: Xavier Vello <xavier.vello@gmail.com> line in the git commit message of the first commit, for attribution?

Of course, added.

[Fizzadar]

Right, maybe it would be best to add a new flag for that. I always would like to see the diff, even when not using -v. So maybe we could add a --diff flag for this; similar to the same Ansible feature.

👍 for --diff, good call.

[goetzk]

I've been waiting on this PR, really excited to see it so close to inclusion :) Thanks heaps to everyone involved!

[Fizzadar]

@jgelens are you happy for me to finish this up with the --diff arg?

[jgelens]

Yeah sure, no problem. Otherwise I can do it next week or so.

[jgelens]

@Fizzadar I'm not sure if adding it to the Config object is enough. See 2381ab9

[jgelens]

@Fizzadar I'm not sure if adding it to the Config object is enough. See 2381ab9

Can you confirm whether this is the right way to implemented flag like this?

[Fizzadar]

@jgelens sorry for the delay - I think this is correct, thank you!

It's made me think we should (not now) move the -v flags over from state -> config to match, and also that --diff should probably set -v=1 if not set as well (to show the "blah is already installed" etc).

[Fizzadar]

Awesome stuff, @jgelens, very excited to land this!