In Ansible, how is the environment keyword used?

Question

I have a playbook to install PythonBrew. In order to do this, I have to modify the shell environment. Because shell steps in Ansible are not persistent, I have to prepend export PYTHONBREW_ROOT=${pythonbrew.root}; source ${pythonbrew.root}/etc/bashrc; to the beginning of each of my PythonBrew-related commands:

    - name: Install python binary
      shell: export PYTHONBREW_ROOT=${pythonbrew.root}; source ${pythonbrew.root}/etc/bashrc; pythonbrew install ${python.version}
        executable=/bin/bash

    - name: Switch to python version
      shell: export PYTHONBREW_ROOT=${pythonbrew.root}; source ${pythonbrew.root}/etc/bashrc; pythonbrew switch ${python.version}
        executable=/bin/bash

I'd like to eliminate that redundancy. On the Ansible discussion group, I was referred the environment keyword. I've looked at the examples in the documentation and it's not clicking for me. To me, the environment keyword doesn't look much different than any other variable.

I've looked for other examples but have only been able to find this very simple example.

Can someone demonstrate how the environment keyword functions in Ansible, preferably with the code sample I've provided above?

score 16 · Accepted Answer · edited Jun 11 '14 at 12:24

16

Not sure if it will fits your need, but this is how I see this :

- hosts: all
  vars:
    env:
      PYTHONBREW_ROOT: "{{ pythonbrew.root }}"
  tasks:  
    - name: Install python binary
      shell: pythonbrew install {{ python.version }} executable=/bin/bash
      environment: env

    - name: Switch to python version
      shell: pythonbrew switch {{ python.version }} executable=/bin/bash
      environment: env

It simply sets a variable named env and reuse it as environment in both of your shell commands. This way your shell command will have the PYTHONBREW_ROOT path set.

edited Jun 11 '14 at 12:24

Christian Berendt

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answered Dec 13 '13 at 08:25

magnetik

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At least with the current version of Ansible this example is **not** working. The line `executable=/bin/bash` has to be on the same line with `shell: ...`. I updated the answer accordingly. – Christian Berendt Jun 11 '14 at 12:16

score 0 · Answer 2 · answered Dec 13 '13 at 18:59

0

I have a very similar issue; I'd like to have ansible do it's stuff inside a Python virtualenv (after it's made sure it's set up for me, of course).

Here's one way I've done the environment preconditions so far; essentially I have had to add (and optionally remove) lines to .bashrc:

  tasks:
    - name: "Enable virtualenv in .bashrc"
      lineinfile: dest=.bashrc
                  line="source {{ PROJECT_HOME }}/venv/bin/activate"

    # Put tasks that rely on this environmental precondition here (?)

    - name: "Disable virtualenv in .bashrc"
      lineinfile: dest=.bashrc
                  line="source {{ PROJECT_HOME }}/venv/bin/activate"
                  state=absent

I don't know if I'm "Doing It Wrong", but until I figure it out or someone comes along to tell me how to do it better, I suppose this will work.

answered Dec 13 '13 at 18:59

Matt Schlobohm

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This is a slightly a different issue. For something like Ansible, rather than activating and deactivating the virtualenv, I just call my command with the full virtualenv python bin path. For example: `command: "{{ PROJECT_HOME }}/venv/bin/python myscript.py"`. It makes your Ansible script a little more transparent. I use virtualenv regularly but actually very rarely activate it in the shell. Usually I'm just calling the python bin from the command line. – klenwell Dec 13 '13 at 19:12
Sure, but since ansible has dependencies that could be in the virtualenv as well, other commands, etc... I usually like to contain as much as I can in the virtualenv and always have it activated when working at the application level. – Matt Schlobohm Dec 13 '13 at 19:20
You can install those dependecies in the control host's project virtualenv using {{PROJECT_HOME}}/venv/bin/pip install ..., but if those are required on the remote hosts things get more complicated because #!/usr/bin/python is in all ansible's libraries. – bbaassssiiee May 14 '14 at 22:39

In Ansible, how is the environment keyword used?

2 Answers2