Emulating Bash 'source' in Python

user_201869 0
Viewed 95024

I have a script that looks something like this:

export foo=/tmp/foo                                          
export bar=/tmp/bar

Every time I build I run 'source init_env' (where init_env is the above script) to set up some variables.

To accomplish the same in Python I had this code running,

reg = re.compile('export (?P<name>\w+)(\=(?P<value>.+))*')
for line in open(file):
    m = reg.match(line)
    if m:
        name = m.group('name')
        value = ''
        if m.group('value'):
            value = m.group('value')
        os.putenv(name, value)

But then someone decided it would be nice to add a line like the following to the init_env file:

export PATH="/foo/bar:/bar/foo:$PATH"

Obviously my Python script fell apart. I could modify the Python script to handle this line, but then it'll just break later on when someone comes up with a new feature to use in the init_env file.

The question is if there is an easy way to run a Bash command and let it modify my os.environ?

python bash
5 Answers

Example wrapping @Brian's excellent answer in a function:

import json
import subprocess

# returns a dictionary of the environment variables resulting from sourcing a file
def env_from_sourcing(file_to_source_path, include_unexported_variables=False):
    source = '%ssource %s' % ("set -a && " if include_unexported_variables else "", file_to_source_path)
    dump = '/usr/bin/python -c "import os, json; print json.dumps(dict(os.environ))"'
    pipe = subprocess.Popen(['/bin/bash', '-c', '%s && %s' % (source, dump)], stdout=subprocess.PIPE)
    return json.loads(pipe.stdout.read())

I'm using this utility function to read aws credentials and docker .env files with include_unexported_variables=True.

user_10073530
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