Add option --dry-run

[andreasabel]

Thanks for this tool! Tried it today in dear need for some diskspace.
I ran

$ stack-clean-old snapshots remove-earlier-minor
4 snapshots removed for 8.6.3
1 snapshots removed for 8.6.4
2 snapshots removed for 8.8.2
33 snapshots removed for 8.10.2

I think I intended to keep 8.10.2 as 8.10.3 is still brand-new...
No big problem, I suppose, but I think an option --dry-run would be terribly useful to see what will happen and if this is what one intends to happen.

Btw, I discovered your tool here: commercialhaskell/stack#133 (comment)

[juhp]

Which version are you using?

$ stack-clean-old --version
0.2.1
$ stack-clean-old snapshots remove-earlier-minor --dryrun
80 snapshots removed for 8.10.2

Maybe --dry-run is more common? You can also use -n.

If you wanted to keep 8.10.2, you could do: $ stack-clean-old snapshots remove-earlier-minor 8.10.2.

Thanks for the feedback.

[andreasabel]

I was using 0.2.1

$ stack-clean-old --version
0.2.1

Oops, I didn't know that a dry-run option was already implemented.

Maybe all that is needed to make it more discoverable. With my attempts to get help, I didn't see it:

$ stack-clean-old --help
Stack clean up tool

Usage: stack-clean-old [--version] COMMAND
  Cleans away old stack-work builds (and pending: stack snapshots) to recover
  diskspace.

Available options:
  -h,--help                Show this help text
  --version                Show version

Available commands:
  project                  Commands for project .stack-work builds
  snapshots                Commands for ~/.stack/snapshots
  ghc                      Commands on stack's ghc compiler installations

$ stack-clean-old snapshots --help
Usage: stack-clean-old snapshots COMMAND
  Commands for ~/.stack/snapshots

Available options:
  -h,--help                Show this help text

Available commands:
  size                     Total size of all stack build snapshots
  list                     List build snapshots per ghc version
  remove-version           Remove build snapshots for a ghc version
  remove-earlier-minor     Remove build snapshots for previous ghc minor
                           versions

If one knows what to look for and tries really hard, one can see it:

$ stack-clean-old snapshots remove-earlier-minor --help
Usage: stack-clean-old snapshots remove-earlier-minor [-n|--dryrun] [GHCVER]
  Remove build snapshots for previous ghc minor versions

Available options:
  -n,--dryrun              Show what would be done, without removing
  -h,--help                Show this help text

But this is the first time in my life that I had to invoke

command subcommand subsubcommand --help

to see an option. I am used to

command --help

and for fat tools like git

command subcommand --help

but I haven't encountered deeper nesting yet.

Maybe the option --dryrun could be moved a bit further up, even if it has null effect on print-only commands like list and size? Wouldn't hurt, I suppose.

Also, I'd agree that --dry-run with a dash is more common.

[juhp]

If you want to try the reworked subcommands in HEAD and have any feedback, that would be nice.

[andreasabel]

Thanks for reworking the command structure! Here is a little feedback...

I tried HEAD (0.3) a bit, but didn't have to remove anything at this moment.

$ stack-clean-old remove 8.0.2 -n
stack-clean-old: stack ghc compiler version 8.0.2 not found

In my case, there isn't a ghc installation, but there are snapshots at 8.0.2:

$ stack-clean-old list
ghc-8.2.2
ghc-8.4.4
...
162M  7.10.3 (2 dirs)
388M  8.0.2  (5 dirs)
210M  8.2.2  (1 dirs)
576M  8.4.4  (4 dirs)
...

So I suppose the message stack ghc compiler version 8.0.2 not found could be complemented by a message saying snapshots would be removed.
Assuming that -g is the default, of course.
Should it say so in the help text?

$ stack-clean-old remove --help
Usage: stack-clean-old remove [-n|--dry-run] 
                              [(-p|--project) | (-s|--snapshots) | 
                                (-c|--compilers) | (-g|--ghc)] GHCVER
  Remove for a ghc version

Available options:
  -n,--dry-run             Show what would be done, without removing
  -p,--project             Act on current project's .stack-work/
  -s,--snapshots           Act on ~/.stack/snapshots/
  -c,--compilers           Act on ~/.stack/programs/
  -g,--ghc                 Act on both ~/.stack/{programs,snapshots}/
  -h,--help                Show this help text

Now, trying with -s:

$ stack-clean-old remove 8.0.2 -s -n
5 snapshots removed for 8.0.2

My heart skipped a beat since I wasn't sure if things had been removed. The message says so, maybe it would be better to say "would be removed" if option -n is given.

[juhp]

Thank you, basically that is a bug: it gives up when finding no compiler...

[juhp]

(Also not sure if --snapshots and --compilers are overkill, maybe what I misnamed --ghc is enough, hm?)

[juhp]

Thank you, basically that is a bug: it gives up when finding no compiler...

Should be fixed now

[andreasabel]

... In my case, there isn't a ghc installation, but there are snapshots at 8.0.2: ...

I confirm that this is fixed now:

$ stack-clean-old remove 8.0.2 -n
stack ghc compiler version 8.0.2 not found
5 snapshots would be removed for 8.0.2

... -g is the default ... Should it say so in the help text?

Does now:

  -g,--ghc                 Act on both ~/.stack/{programs,snapshots}/ [default
                           outside project dir]

Thanks!

The name choice --ghc is indeed surprising, what about --all?

[juhp]

Right, I went with --global for now

Thanks for all the constructive feedback and testing :-)

[juhp]

I think we can close this, but if you notice anything directly related you can still comment or open a new issue, thanks!

[andreasabel]

Thanks for the prompt addressing of this issue!

[juhp]

I finally released 0.3 btw