Mastering the Ansible Fetch Module: Effortless File Retrieval

Introduction

Welcome to the Ansible Fetch Module Lab! In this lab, you will dive into the usage of the Ansible Fetch module. The Fetch module allows you to retrieve files from remote machines and copy them to the control machine where Ansible is being executed. This is useful when you need to collect specific files or artifacts from your managed hosts.

Let's get started!

Fetching a Single File

In this step, you will learn how to use the Ansible Fetch module to retrieve a single file from a remote machine. This will help you understand the basic usage and syntax of the module.

First, complete /home/labex/project/fetching_a_single_file.yml file.
Open it in a text editor and add the following content to the playbook file:

- name: Fetch Module Lab
  hosts: localhost
  gather_facts: false

  tasks:
    - name: Fetch a single file
      fetch:
        src: /home/labex/example/example_1.txt
        dest: /home/labex/project/example_1.txt
        flat: true

fetch: This is the Ansible module used to fetch files from remote hosts.
src: This specifies the path of the file on the remote host that needs to be fetched. In this example, it's /home/labex/example/example_1.txt.
dest: This specifies the destination path where the fetched file should be stored on the local host. In this example, it's /home/labex/project/example_1.txt.
flat: This parameter controls the behavior of the destination path. When set to true, it ensures that the fetched file is placed in the destination directory without creating any subdirectories. This is useful when fetching a single file and wanting to keep the directory structure simple.

The fetch module in Ansible is used to fetch files from remote hosts to the local host. In this configuration, it's used to fetch a file named "example_1.txt" from the remote host's /home/labex/example/ directory and store it as "example_1.txt" in the local host's /home/labex/project/ directory. The flat: true parameter ensures that the fetched file is placed directly in the destination directory without any subdirectories.

Then, run the playbook with the following command:

ansible-playbook fetching_a_single_file.yml

Example output:

[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that
the implicit localhost does not match 'all'

PLAY [Fetch Module Lab] **************************************************

TASK [Fetch a single file] *****************************************************
changed: [localhost]

PLAY RECAP *********************************************************************
localhost                  : ok=1    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Finally, verify that the example_1.txt file has been fetched locally from the remote host.

ll /home/labex/project/example_1.txt

Example output:

-rw-rw-r-- 1 labex labex 23 Mar 14 10:45 /home/labex/project/example_1.txt

Fetching Multiple Files

In this step, you will enhance your understanding of the Fetch module by fetching multiple files from a remote machine. This will allow you to collect multiple files in a single task.

First, complete /home/labex/project/fetching_multiple_files.yml file.
Open it in a text editor and add the following content to the playbook file:

- name: Fetch Module Lab
  hosts: localhost
  gather_facts: false

  tasks:
    - name: Fetch multiple files
      loop:
        - example_2.txt
        - example_3.txt
      fetch:
        src: "/home/labex/example/{{ item }}"
        dest: "/home/labex/project/{{ item }}"
        flat: true

loop: This keyword is used to iterate over a list of items.
fetch: This is the Ansible module used to fetch files from remote hosts.
src: This specifies the source path of the file to be fetched. The {{ item }} placeholder is replaced with each item from the loop, resulting in fetching example_2.txt and example_3.txt from the /home/labex/example/ directory.
dest: This specifies the destination path where the fetched files should be stored. Again, the {{ item }} placeholder is used to ensure that each file is placed in the corresponding directory within /home/labex/project/.
flat: This parameter controls the behavior of the destination path. When set to true, it ensures that the fetched file is placed in the destination directory without creating any subdirectories. This is useful when fetching a single file and wanting to keep the directory structure simple.

In this configuration, it's used to fetch multiple files (example_2.txt and example_3.txt) from the /home/labex/example/ directory on the local host and store them in the corresponding directories within /home/labex/project/. The loop construct allows iterating over a list of items and performing the fetch operation for each item in the list.

Then, run the playbook with the following command:

ansible-playbook fetching_multiple_files.yml

Example output:

[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that
the implicit localhost does not match 'all'

PLAY [Fetch Module Lab] **************************************************

TASK [Fetch multiple files] ****************************************************
changed: [localhost] => (item=example_2.txt)
changed: [localhost] => (item=example_3.txt)

PLAY RECAP *********************************************************************
localhost                  : ok=1    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Finally, verify that example_2.txt and example_3.txt have been fetched locally from the remote host.

ll /home/labex/project/ | grep example

Example output:

-rw-rw-r-- 1 labex labex  23 Mar 14 10:45 example_1.txt
-rw-rw-r-- 1 labex labex  23 Mar 14 11:00 example_2.txt
-rw-rw-r-- 1 labex labex  23 Mar 14 11:00 example_3.txt

Using Variables in Fetch Module

In this step, you will explore a more advanced usage of the Ansible Fetch module by incorporating variables. You will fetch files based on dynamic values defined in your playbook.

First, complete /home/labex/project/using_variablesin_fetch_modules.yml file.
Open it in a text editor and add the following content to the playbook file:

- name: Fetch Module Lab
  hosts: localhost
  gather_facts: false
  vars:
    file_path: "/home/labex/example/example_4.txt"
    dest_path: "/home/labex/project/example_4.txt"

  tasks:
    - name: Fetch files using variables
      fetch:
        src: "{{ file_path }}"
        dest: "{{ dest_path }}"
        flat: true

vars: This section allows defining variables to be used within the playbook.
fetch: This is the Ansible module used to fetch files from remote hosts.
src: This specifies the source path of the file to be fetched. It uses the file_path variable to dynamically provide the source file path.
dest: This specifies the destination path where the fetched file should be stored. It uses the dest_path variable to dynamically provide the destination file path.
flat: This parameter controls the behavior of the destination path. When set to true, it ensures that the fetched file is placed in the destination directory without creating any subdirectories. This is useful when fetching a single file and wanting to keep the directory structure simple.

In this configuration, it's used to fetch a file from the source file path (file_path variable) on the remote host and store it in the destination file path (dest_path variable) on the local Ansible control node. The use of variables allows for dynamic specification of file paths, providing flexibility and reusability in the playbook.

Then, run the playbook with the following command:

ansible-playbook using_variablesin_fetch_modules.yml

Example output:

[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that
the implicit localhost does not match 'all'

PLAY [Fetch Module Lab] **************************************************

TASK [Fetch files using variables] *********************************************
changed: [localhost]

PLAY RECAP *********************************************************************
localhost                  : ok=1    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Next, verify that the example_4.txt file has been fetched locally from the remote host.

ll /home/labex/project/example_4.txt

Example output:

-rw-rw-r-- 1 labex labex 23 Mar 14 11:16 /home/labex/project/example_4.txt

Finally, try specifying file_path and dest_path with the -e option:

ansible-playbook using_variablesin_fetch_modules.yml -e file_path="/tmp/example_5.txt" -e dest_path="/tmp/target/example_5.txt"

Example output:

[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that
the implicit localhost does not match 'all'

PLAY [Fetch Module Lab] **************************************************

TASK [Fetch files using variables] *********************************************
changed: [localhost]

PLAY RECAP *********************************************************************
localhost                  : ok=1    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Verify that the example_5.txt file has been fetched locally from the remote host.

ll /tmp/target/example_5.txt

Example output:

-rw-rw-r-- 1 labex labex 23 Mar 14 11:24 /tmp/target/example_5.txt

Summary

Congratulations on completing the Ansible Fetch Module Lab! In this lab, you learned how to use the Ansible Fetch module to retrieve files from remote machines and copy them to the control machine. Starting with fetching a single file, you progressed to fetching multiple files and incorporating variables for dynamic file retrieval.

By completing this lab, you have gained valuable experience in leveraging the Fetch module to collect specific files or artifacts from your managed hosts. Keep exploring Ansible and its modules to further enhance your automation capabilities.

Happy automating!