"extends" path using an environment variable not working as expected

[qjcg]

I'm trying to get lefthook to use hooks from a custom external directory defined via an environment variable
(e.g. extends: $HOOKDIR/hooks.yml).

So far I haven't been able to get it working, but maybe I'm missing something obvious.

Steps to reproduce (tested using bash):

# 1. A basic hook for testing purposes.
$ cat hooks.yml 
pre-commit:
  commands:
    greet:
      run: echo 'Extended hooks!'

# 2. Export a HOOKDIR environment variable and copy our hook file there.
$ export HOOKDIR=/tmp
$ cp hooks.yml $HOOKDIR

# 3. Tell lefthook about our external hooks file and test running the hook. It fails :( <--THIS IS THE ISSUE
$ echo 'extends: $HOOKDIR/hooks.yml' > lefthook.yml
$ lefthook run pre-commit
runtime error: slice bounds out of range [:-1]

# 4. Repeat steps 2 & 3 using $HOME instead of $HOOKDIR. It works! :)
$ cp hooks.yml $HOME
$ echo 'extends: $HOME/hooks.yml' > lefthook.yml
$ lefthook run pre-commit
Lefthook v0.7.2
RUNNING HOOKS GROUP: pre-commit

  EXECUTE > greet
Extended hooks!

SUMMARY: (done in 0.02 seconds)
✔️  greet

For context:

Remote config as in #118 would be a better solution for my use case (sharing a standard set of common hooks across repos for a team of developers), but unless / until that PR gets merged, I'll be looking at extends: plus an env-defined local path as the next best thing.

[qjcg]

Looking into this, the root cause of this issue is viper's absPathify function (as called by the AddConfigPath method). It currently fails when provided with a path starting with an environment variable and containing a single pre-expansion path separator (excluding $HOME, which is handled differently than other env vars).

So:

• $HOOKDIR/hooks.yml will fail (one pre-expansion path separator), but
• $HOOKDIR/shared/hooks.yml (2 pre-expansion path separators) will succeed

The good news is, there's spf13/viper#495 which fixes the issue and adds a solid unit test (outside of this PR, viper does not currently test absPathify). The bad news is, the PR's been pending, with no comments, for over 2 years...

So, until there's an upstream fix in viper, a workaround for lefthook users could be to always use at least 2 pre-expansion path separators when using non-$HOME environment variables with extends, as in:

extends: $HOOKDIR/shared/hooks.yml.

[qjcg]

Finally I got a fix merged for this upstream: spf13/viper#940

So the issue described above in lefthook should be resolved by updating the viper dependency to v1.7.1.

[qjcg]

Closed by #148.