Ansible: Pass command arguments as a list

问题

I want to store multiple arguments in a variable as a list.

vars:
  my_args:
    - --verbose
    - --quiet
    - --verify

Then pass the list as quoted arguments to a command. The most obvious join filter doesn't work as I expected. It produces a single word containing all list elements as opposed to one word per list element:

tasks:
  - command: printf '%s\n' "{{ my_args | join(' ') }}"
...
changed: [localhost] => {
"changed": true,
"cmd": [
    "printf",
    "%s\\n",
    " --quiet  --verbose  --verify "
],

STDOUT:

 --quiet  --verbose  --verify

How to pass them to a command?

回答1:

To pass a list elements as arguments to a module use either map('quote') | join(' ') filters or the for loop:

tasks:

- name: Pass a list as arguments to a command using filters
  command: executable {{ my_args | map('quote') | join(' ') }}

- name: Pass a list as arguments to a command using for loop
  command: executable {% for arg in my_args %} "{{ arg }}" {% endfor %}

Do not use quotes with filter, but do use them with a loop. Although being slightly longer, the for loop gives more possibilities of shaping the output. For example prefixing or suffixing the list item like "prefix {{ item }} suffix", or applying filters to the item or even selectively processing items using loop.* variables.

The example in question would be:

tasks:
  - command: printf '%s\n' {{ my_args | map('quote') | join(' ') }}
  - command: printf '%s\n' {% for arg in my_args %} "{{ arg }}" {% endfor %}
...
changed: [localhost] => {
    "changed": true,
    "cmd": [
        "printf",
        "%s\\n",
        "--quiet",
        "--verbose",
        "--verify"
    ],

STDOUT:

--quiet
--verbose
--verify

List elements are not limited to simple strings and can contain some logic:

vars:
  my_args:
    - --dir={{ my_dir }}
    - {% if my_option is defined %} --option={{ my_option }} {% endif %}

来源：https://stackoverflow.com/questions/49799595/ansible-pass-command-arguments-as-a-list

标签

ansible