Ansible Write to File: Variable Content with copy & template Modules — Video Tutorial

How to write variables to files in Ansible. Compare copy content vs template module, write JSON/YAML, and generate dynamic config files with examples.

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What you'll learn

How to write a variable to file with Ansible?
Ansible modules: copy vs template
Ansible module copy - Write Variable to a File
Ansible module template - Write Variable to a File
Ansible copy module code
Ansible copy module execution
Ansible copy module idempotency
Ansible copy module before execution
Ansible copy module after execution
Ansible copy module code

How to write a variable to file with Ansible? From a simple value or the result of complex command execution on the target node often we have the need to write the result to a file. Ansible modules: copy vs template - `ansible.builtin.copy` It deals with whitespace and newlines. The quotes are important. - `ansible.builtin.template` For advanced formatting or if the content contains a variable, use the `ansible.builtin.template` module. The `copy` and `template` Ansible modules have the ability to write variables to a file. Long story short: use the `template` module instead of the `copy` module. Both modules write variables to a file but the template module is the safer way for advanced formatting or if the content contains a variable. Preferred also by the early adopter of Ansible, the `copy` module that deals with whitespace and newlines but performs poorly with quotes and escapes contents. On the other hand, the `template` module is the best option for advanced formatting or if the content contains a variable. Ansible module copy - Write Variable to a File - Ansible Playbook task: ```yaml - name: write to file ansible.builtin.copy: content: "{{ fruit }}" dest: "/path/to/destination/file" ``` The main advantage to use the Ansible copy module to Write Variable to a File is that you could write it all in one Ansible Playbook file. In this example, the parameter `content` specifies the name of the `fruit` variable to be written to the `dest` parameter, the path of the destination file. Ansible module template - Write Variable to a File - Ansible Playbook task: ```yaml - name: write to file ansible.builtin.template: src: "mytemplate.j2" dest: "/path/to/destination/file" ``` - mytemplate.j2 ```yaml {{ fruit }} ``` On the other hand, the Ansible module `template` is the best option to write variables to a file. Unfortunately, this module doesn't have any `content` parameter so you need to create a secondary template file to output the `fruit` variable. As you could see in this simple example the writing to file process is started in the main Ansible Playbook file, triggering the `mytemplate.j2` Jinja2 template that only output the content of the `fruit` variable. The result is written to the `dest`, the destination file defined in the Ansible Playbook. ## Playbook How to write variables to a file with Ansible Playbook. Ansible copy module code ```yaml --- - name: copy module Playbook hosts: all vars: fruit: "banana" output: "output.txt" tasks: - name: write to file ansible.builtin.copy: content: "{{ fruit }}" dest: "{{ output }}" ``` Ansible copy module execution ```bash ansible-pilot $ ansible-playbook -i virtualmachines/demo/inventory variables/write-file-copy.yml PLAY [copy module Playbook] *************************************************************************** TASK [Gathering Facts] ***************************************************************************

About this tutorial

Author: Luca Berton
Difficulty: Advanced
Read time: 8 min
Category: troubleshooting

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