Ansible is an open-source automation tool that allows you to manage and configure systems. The ansible-pull command is used to quickly pull desired Ansible playbooks from a version control system (VCS) repository and execute them on the local host. This command simplifies the process of applying configurations to a local machine without requiring a centralized control node.

Use case 1: Pull a playbook from a VCS and execute a default local.yml playbook

Code:

ansible-pull -U repository_url

Motivation: In this use case, we pull a playbook from a VCS repository specified by the repository_url parameter and execute the default local.yml playbook. This is useful when you have a common playbook that needs to be run on multiple local machines.

Explanation:

• -U repository_url specifies the URL of the VCS repository where the playbook is located. The repository can be either Git or Mercurial.

Example Output:

PLAY [localhost] *****************************************************************************************

TASK [Gathering Facts] ************************************************************************************
ok: [localhost]

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

Use case 2: Pull a playbook from a VCS and execute a specific playbook

Code:

ansible-pull -U repository_url playbook

Motivation: This use case is helpful when you want to pull a specific playbook from a VCS repository using the repository_url parameter. It allows you to execute a playbook that targets specific configurations for the local host.

Explanation:

• -U repository_url specifies the URL of the VCS repository where the playbook is located.
• playbook is the name of the playbook to be executed.

Example Output:

PLAY [localhost] *****************************************************************************************

TASK [task1] **********************************************************************************************
ok: [localhost] => {
    "msg": "This is task 1"
}

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

Use case 3: Pull a playbook from a VCS at a specific branch and execute a specific playbook

Code:

ansible-pull -U repository_url -C branch playbook

Motivation: In this use case, we specify a specific branch of the VCS repository using the -C branch parameter. This allows you to pull the playbook from a particular branch and execute a specific playbook in that branch.

Explanation:

• -U repository_url specifies the URL of the VCS repository where the playbook is located.
• -C branch specifies the branch from which to pull the playbook.
• playbook is the name of the playbook to be executed.

Example Output:

PLAY [localhost] *****************************************************************************************

TASK [task1] **********************************************************************************************
ok: [localhost] => {
    "msg": "This is task 1"
}

TASK [task2] **********************************************************************************************
ok: [localhost] => {
    "msg": "This is task 2"
}

PLAY RECAP ***********************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Use case 4: Pull a playbook from a VCS, specify hosts file and execute a specific playbook

Code:

ansible-pull -U repository_url -i hosts_file playbook

Motivation: This use case allows you to specify a custom hosts file using the -i hosts_file parameter. It enables you to execute a specific playbook on a set of hosts defined in the custom hosts file.

Explanation:

• -U repository_url specifies the URL of the VCS repository where the playbook is located.
• -i hosts_file specifies the path to the custom hosts file.
• playbook is the name of the playbook to be executed.

Example Output:

PLAY [custom_hosts] ****************************************************************************************

TASK [task1] **********************************************************************************************
ok: [host1] => {
    "msg": "This is task 1"
}
ok: [host2] => {
    "msg": "This is task 1"
}

PLAY RECAP ***********************************************************************************************
host1                      : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
host2                      : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Conclusion:

The ansible-pull command is a versatile tool for quickly pulling and executing Ansible playbooks from a VCS repository on the local host. By understanding the various use cases and options available, you can streamline the configuration management process and efficiently apply configurations to your local machines.