Best way to add an environment variable in fabric?

Question

I would like to pass a few values from fabric into the remote environment, and I'm not seeing a great way to do it. The best I've come up with so far is:

with prefix('export FOO=BAR'):     run('env | grep BAR') 

This does seem to work, but it seems like a bit of a hack.

I looked in the GIT repository and it looks like this is issue #263.

Answer 1

As of fabric 1.5 (released), fabric.context_managers.shell_env does what you want.

    with shell_env(FOO1='BAR1', FOO2='BAR2', FOO3='BAR3'):         local("echo FOO1 is $FOO1") 

Answer 2

I think your prefix-based solution is perfectly valid. However, if you want to have a shell_env context manager as the one proposed in issue#263, you can use the following alternative implementation in your fab files:

from fabric.api import run, env, prefix from contextlib import contextmanager  @contextmanager def shell_env(**env_vars):     orig_shell = env['shell']     env_vars_str = ' '.join('{0}={1}'.format(key, value)                            for key, value in env_vars.items())     env['shell']='{0} {1}'.format(env_vars_str, orig_shell)     yield     env['shell']= orig_shell  def my_task():     with prefix('echo FOO1=$FOO1, FOO2=$FOO2, FOO3=$FOO3'):         with shell_env(FOO1='BAR1', FOO2='BAR2', FOO3='BAR3'):             run('env | grep BAR') 

Note that this context manager modifies env['shell'] instead of env['command_prefixes'] (as prefix context manager does), so you:

• can still use prefix (see example output below) without the interaction problems mentioned in issue#263.
• have to apply any changes to env['shell'] before using shell_env. Otherwise, shell_env changes will be overwritten and environment variables won't be available for your commands.

When executing the fab file above, you get the following output:

$ fab -H localhost my_task [localhost] Executing task 'my_task' [localhost] run: env | grep BAR [localhost] out: FOO1=BAR1, FOO2=BAR2, FOO3=BAR3 [localhost] out: FOO1=BAR1 [localhost] out: FOO2=BAR2 [localhost] out: FOO3=BAR3 [localhost] out:   Done. Disconnecting from localhost... done.