python - Path to stat module via dict variable

Question

I want to register status of a file with the stat module so that I can set permissions if it exists.

In the following tasks, I send variables to the cron and file modules. What is a good way to make those same variables available to the stat module, or what is an alternate method of checking for the existence of a file based on dict variables?

- name: Task One
  cron:
    name: "{{ item.key }} nightly S3 backup"
    minute: "0"
    hour: "12"
    user: "{{ web_user }}"
    job: "cd {{ www_root }}/{{ item.key }}/{{ item.value.current_path | default('current') }}/scripts && ./backup-to-s3.sh > /dev/null 2>&1"
    cron_file: "backup-nightly-{{ item.key | replace('.', '_') }}"
  with_dict: "{{ my_dictionary }}"

- name: Task Two
  stat:
    path: "{{ www_root }}/{{ item.key }}/{{ item.value.current_path | default('current') }}/scripts/backup-to-s3.sh"
    register: stat_result

- name: Task Three
  file:
    path: "{{ www_root }}/{{ item.key }}/{{ item.value.current_path | default('current') }}/scripts/backup-to-s3.sh"
    owner: "{{ web_user }}"
    group: "{{ web_group }}"
    mode: 0755
  when: stat_result.stat.exists == True
  with_dict: "{{ my_dictionary }}"

my_dictionary:
  example.com:
    site_hosts:
      - canonical: example.com
    local_path: ../example.com
    env:
      db_prefix: my_

I am thinking maybe with_items will be at at least part of the solution.

标签： pythonansiblestat

Answer 1

Q: "Check for the existence of a file based on dict variables."

A: Short answer: Create a dictionary of the files and their statuses. Use it in the conditions.

Details

1) Register stat_result in the loop

- name: Task Two
  stat:
    path: "{{ www_root }}/{{ item.key }}/{{ item.value.current_path | ...
  register: stat_result
  with_dict: "{{ my_dictionary }}"

2) Create the dictionary

- set_fact:
    files_stat: "{{ dict(stat_result.results|
                    json_query('[].[item.key, stat.exists]')) }}"

• See Combining items from multiple lists
• See Filters and Multiselect Lists

3) Use the dictionary in the condition

- name: Task Three
  file:
    path: "{{ www_root }}/{{ item.key }}/{{ item.value.current_path | ...
    owner: "{{ web_user }}"
    group: "{{ web_group }}"
    mode: 0755
  with_dict: "{{ my_dictionary }}"
  when: files_stat[item.key]

---

Example

- hosts: localhost

  vars:
    my_dictionary:
      file1:
        local_path: "find_cpy/file1.ext"
      file2:
        local_path: "find_cpy/file2.ext"
      file3:
        local_path: "find_cpy/file9.ext"

  tasks:
    - stat:
        path: "{{ item.value.local_path }}"
      register: stat_result
      with_dict: "{{ my_dictionary }}"

    - set_fact:
        files_stat: "{{ dict(stat_result.results|
                        json_query('[].[item.key, stat.exists]')) }}"
    - debug:
        var: files_stat

    - file:
        state: file
        mode: "0644"
        path: "{{ item.value.local_path }}"
      with_dict: "{{ my_dictionary }}"
      when: files_stat[item.key]

give

TASK [debug] ***
ok: [localhost] => {
    "files_stat": {
        "file1": true, 
        "file2": true, 
        "file3": false
    }
}

TASK [file] ***
skipping: [localhost] => (item={'value': {u'local_path': u'find_cpy/file9.ext'}, 'key': u'file3'}) 
ok: [localhost] => (item={'value': {u'local_path': u'find_cpy/file2.ext'}, 'key': u'file2'})
ok: [localhost] => (item={'value': {u'local_path': u'find_cpy/file1.ext'}, 'key': u'file1'})

---

Q: "json_query requires installing jmespath. Would you offer an approach without that requirement?"

A: The task below creates the same dictionary without json_query.

    - set_fact:
        files_stat: "{{ dict(my_keys|zip(my_stats)) }}"
      vars:
        my_keys: "{{ stat_result.results|map(attribute='item.key')|list }}"
        my_stats: "{{ stat_result.results|map(attribute='stat.exists')|list }}"

See Combining items from multiple lists.