Ansible Docker Environment Lookup Plugin

Readme_docker_envs.md

Quick lookup plugin for ansible. I needed a clean way to pass an unknown amount of local envs via params when creating a docker container, based on the env vars on the CI server.

Run the playbook to test with: ansible-playbook -i localhost, playbook.yml

Note: This was thrown together very quickly, I'll hopfully have some time to expand this plugin with proper documention and error handling.

Note original (non plugin route was) ugly and hacky:

---
- name: Get all local envs for dynamic docker injection
  shell: env | grep ^SEARCH_PREFIX_
  # When nothing found by grep return code is 1, this is fine.
  ignore_errors: yes
  register: app_envs

- name: Build list of docker app params
  shell: |
    echo "{% for x in app_envs.stdout_lines %}
    -e {{ "{}={}".format(x.split('=', 1)[0], x.split('=', 1)[1].replace('\"','\\\"')) }}
    {% endfor %}
    "
  register: docker_env_params

lookup_plugins\docker_envs.py

# Kyle James Walker <KyleJamesWalker@gmail.com>
#
# This file is a lookup plugin for Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.


import os
import re

from ansible.utils import template


class LookupModule(object):
    def __init__(self, basedir=None, **kwargs):
        self.basedir = basedir
        self.search_string = ''
        self.format_envs = '-e {}={}'
        self.join_by = ' '

    def escape_val(self, val):
        quotes = '\'"'
        requote = False
        try:
            if val[0] == val[-1] and val[0] in quotes:
                requote = val[0]
                val = val[1:-1]

            val = val.replace('\\', '\\\\')
            if requote is not False:
                val = val.replace(requote, "\\{}".format(requote))
            else:
                for x in quotes:
                    val = val.replace(x, "\\{}".format(x))

            if requote is not False:
                val = "{0}{1}{0}".format(requote, val)
        except IndexError:
            pass

        return val

    def build_params(self, terms):
        ''' Expect up to three params passed
            1. Regex search string.
            2. Optional format string.
            3. Optional join by string.
        '''
        self.search_string = terms[0]
        if len(terms) > 1 and terms[1] is not None:
            self.format_envs = terms[1]
        if len(terms) > 2 and terms[2] is not None:
            self.join_by = terms[2]

    def build_return(self, results):
        build = [self.format_envs.format(n, self.escape_val(v))
                 for n, v in results]
        return [self.join_by.join(build)]

    def run(self, terms, inject=None, **kwargs):
        results = []

        try:
            terms = template.template(self.basedir, terms, inject)
        except Exception:
            pass

        if isinstance(terms, basestring):
            terms = [terms]

        self.build_params(terms)

        search_re = re.compile(self.search_string)
        for e_name in os.environ.keys():
            if search_re.match(e_name):
                e_val = os.getenv(e_name)
                results.append((e_name, e_val),)

        return self.build_return(results)

playbook.yml

---
- name: Testing lookup docker_envs
  hosts: localhost
  connection: local
  tasks:
    - name: debug
      debug: msg="{{lookup('docker_envs', '^DOCKER_.*')}}"

    - name: debug
      debug: msg="{{lookup('docker_envs', ['^DOCKER_.*', None, '\n'])}}"

    - name: debug
      debug: msg="{{lookup('docker_envs', ['^DOCKER_.*', '{}="{}"', '\n'])}}"