Ansible ad-hoc is a feature of Ansible that allows you to run simple, one-time commands on remote hosts without the need for writing a playbook. It provides a way to perform quick tasks or execute ad-hoc operations on multiple hosts simultaneously. Ad-hoc commands are useful for tasks that don't require complex orchestration or are not part of a larger automation workflow.
When using ad-hoc commands, you can specify the target hosts, the module to run, and any necessary arguments directly from the command line. Ansible will connect to the specified hosts via SSH or other transport mechanisms and execute the command using the specified module.
The syntax for running an ad-hoc command is as follows:
ansible <hosts> -m <module> -a "<arguments>"
Here, `<hosts>` can be a specific host or group from the inventory, `module` represents the task to be performed, and `<arguments>` provide additional details or parameters for the task.
Some commonly used modules for ad-hoc commands include `command`, `shell`, `copy`, `apt`, `yum`, `service`, `ping`, and `setup`. Each module has its own set of arguments and options to customize the behavior of the command.
Ansible ad-hoc commands allow you to execute one-off tasks or perform quick operations on remote hosts without the need to create a playbook. Ad-hoc commands are useful for tasks that do not require complex orchestration or are not part of a larger automation workflow. Here's an example of how to use Ansible ad-hoc commands:
1. Ping all hosts in an inventory:
ansible all -m ping
This command sends a ping to all hosts defined in the inventory and checks if they are reachable.
2. Run a command on remote hosts:
ansible all -m command -a "ls -l /path/to/directory"
This command executes the `ls -l /path/to/directory` command on all hosts defined in the inventory and displays the output.
3. Copy a file to remote hosts:
ansible all -m copy -a "src=/local/path/file.txt dest=/remote/path/"
This command copies the file `file.txt` from the local machine to the `/remote/path/` directory on all hosts defined in the inventory.
4. Install a package on remote hosts:
ansible all -m package -a "name=nginx state=present"
This command installs the `nginx` package on all hosts defined in the inventory using the package manager appropriate for the target system.
5. Gather facts from remote hosts:
ansible all -m setup
This command gathers facts about the remote hosts, including hardware details, network interfaces, operating system information, and more.
These examples demonstrate the basic syntax of Ansible ad-hoc commands. The command starts with `ansible`, followed by the target hosts (e.g., `all` or a specific host/group from the inventory), the module (`-m`) specifying the task to perform, and the module arguments (`-a`) providing additional details for the task.
Ad-hoc commands are useful for quick tasks or troubleshooting scenarios. However, for complex and repeatable tasks, it is recommended to create playbooks to maintain code reusability, readability, and better management of your infrastructure configuration.
