Can I copy text from remote to local with Ansible playbook? - shell

Question

I know the Ansible fetch-module can copy a file from remote to local, but what if I only need the contents (in my case a tmp file holding the ip address) appended into a local file?
Fetch module does this:
- name: Store file into /tmp/fetched/
ansible.builtin.fetch:
src: /tmp/somefile
dest: /tmp/fetched
I need it to do something like this:
- name: Store file into /tmp/fetched/
ansible.builtin.fetch:
src: /tmp/somefile.txt
dest: cat src >> /tmp/fetched.txt

Answer 1

In a nutshell:
- name: Get remote file content
ansible.builtin.slurp:
src: /tmp/somefile.txt
register: somefile
- name: Append remote file content to a local file
vars:
target_file: /tmp/fetched.txt
ansible.builtin.copy:
content: |-
{{ lookup('file', target_file) }}
{{ somefile.content | b64decode }}
dest: "{{ target_file }}"
# Fix write concurrency when running on multiple targets
throttle: 1
delegate_to: localhost
Notes:
the second task isn't idempotent (will modify the file on each run even with the same content to append)
this will work for small target files. If that file becomes huge and you experience high execution times / memory consumptions, you might want to switch to shell for the second task:
- name: Append remote file content to a local file
ansible.builtin.shell:
cmd: echo "{{ somefile.content | b64decode }}" >> /tmp/fetched
# You might still want to avoid concurrency with multiple targets
throttle: 1
delegate_to: localhost
Alternatively, you could write all contents from all fetched files from all your targets in one go to avoid the concurrency problem and gain some time.
# Copy solution
- name: Append remote files contents to a local file
vars:
target_file: /tmp/fetched.txt
fetched_content: "{{ ansible_play_hosts
| map('extract', hostvars, 'somefile.content')
| map('b64decode')
| join('\n') }}"
ansible.builtin.copy:
content: |-
{{ lookup('file', target_file) }}
{{ fetched_content }}
dest: "{{ target_file }}"
delegate_to: localhost
run_once: true
# Shell solution
- name: Append remote files contents to a local file
vars:
fetched_content: "{{ ansible_play_hosts
| map('extract', hostvars, 'somefile.content')
| map('b64decode')
| join('\n') }}"
ansible.builtin.shell:
cmd: echo "{{ fetched_content }}" >> /tmp/fetched
delegate_to: localhost
run_once: true