Executing python subprocess via git hook

Question

I'm running Gitolite over the Git repository and I have post-receive hook there written in Python. I need to execute "git" command at git repository directory. There are few lines of code:

proc = subprocess.Popen(['git', 'log', '-n1'], cwd='/home/git/repos/testing.git' stdout=subprocess.PIPE, stderr=subprocess.PIPE)
proc.communicate()

After I make new commit and push to repository, scripts executes and says

fatal: Not a git repository: '.'

If I run

proc = subprocess.Popen(['pwd'], cwd='/home/git/repos/testing.git' stdout=subprocess.PIPE, stderr=subprocess.PIPE)

it says, as expected, correct path to git repository (/home/git/repos/testing.git)

If I run this script manually from bash, it works correct and show correct output of "git log". What I'm doing wrong?

Martijn Pieters · Accepted Answer · 2012-06-08 14:28:49Z

4

You could try to set the git repository using a command-line switch:

proc = subprocess.Popen(['git', '--git-dir', '/home/git/repos/testing.git', 'log', '-n1'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)

--git-dir needs to point to an actual git directory (.git in a working tree). Note that for some commands you also need to set a --work-tree option too.

Another way to set the directory is using the GIT_DIR environment variable:

import os
env = os.environ.copy()
env['GIT_DIR'] = '/home/git/repos/testing.git'
proc = subprocess.Popen((['git', 'log', '-n1', stdout=subprocess.PIPE, stderr=subprocess.PIPE, env=env)

Apparently hooks already set GIT_DIR but obviously this is incorrect for your case (it could be relative); the above code sets it to a full, explicit path.

See the git manpage.

Edit: Apparently it only works for the OP when specifying both a cwd and overriding the GIT_DIR var:

import os
repo = '/home/git/repos/testing.git'
env = os.environ.copy()
env['GIT_DIR'] = repo
proc = subprocess.Popen((['git', 'log', '-n1', stdout=subprocess.PIPE, stderr=subprocess.PIPE, env=env, cwd=repo)

edited Jun 8, 2012 at 14:28

answered Jun 7, 2012 at 16:38

Martijn Pieters

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5 Comments

torek Over a year ago

Hooks are run with the environment variable $GIT_DIR set already, so if you want to point git at a different directory, you have to override that. Note that in general the hook is run with GIT_DIR=. as well (i.e., it's relative, which was a surprise to me). Best to either clear it out entirely or set it to what you want though.

Martijn Pieters Over a year ago

@torek: interesting, this may be what is wrong for the OP. Updated the answer, as env.update(os.environ) would have wiped the custom GIT_DIR var we are trying to set.

torek Over a year ago

Oh, hah, I didn't read your second part of your answer closely enough to realize that you were using .update that way. Anyway, yes, I suspect that's the OP's real issue. (Experimentation tells me that --git-dir overrides $GIT_DIR so your first answer should work.)

Alex Over a year ago

Thank you very much, I didn't even expect any env vars here. Now, it only works with redefined 'GIT_DIR' variable AND specified 'cwd' option in Popen method. Please add it to your answer.

Juan Antonio Over a year ago

Thanks you very much. I've been trying some solutions but yours (in the edit section ) is the best and simplest that I've seen.

gypaetus · Accepted Answer · 2012-06-07 16:37:26Z

0

There is a comma missing after the cwd argument:

proc = subprocess.Popen(['git', 'log', '-n1'], cwd='/home/git/repos/testing.git', stdout=subprocess.PIPE, stderr=subprocess.PIPE)

answered Jun 7, 2012 at 16:37

gypaetus

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1 Comment

Martijn Pieters Over a year ago

That can hardly be it; that would give a SyntaxError, not the error the user saw. Prolly a transciption error when posting on SO.

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