1-Day1-2-AnsibleAd-hocCommands

Introduction to Ansible Ad-hoc Commands

• What are Ad-hoc Commands?

  • Ansible ad hoc commands use the /usr/bin/ansible command-line tool to automate a single task on one or more managed nodes.

  • They are quick and easy but not reusable.

  • Ad hoc commands demonstrate the simplicity and power of Ansible.

  • Concepts learned here directly apply to playbook development.

If you are familiar with Linux, we can compare the Ansible ad hoc commands with one-liner Linux shell commands; and the playbooks to shell script.

Refer the official Ansible documentation for more information.

• Use Cases for Ad-hoc Tasks:

  • Rebooting servers

  • Managing files

  • Installing packages

  • Managing users and groups

  • Managing services

  • Gathering facts

  • Check mode (dry run)

  • And more!

Practical Examples of Ansible Ad-hoc Commands

1. Ping All Hosts:

   • Verify connectivity to all hosts.

   • Command: $ ansible all -m ping

   • Sample Output:

     server1 | SUCCESS => {
         "changed": false,
         "ping": "pong"
     }
     server2 | SUCCESS => {
         "changed": false,
         "ping": "pong"
     }

(This is not the OS ping command,it is an Ansible module named ping)*

1. Check Uptime:

   • Get uptime information from hosts.

   • Command: $ ansible all -a "uptime"

   • Sample Output:

     server1 | CHANGED | rc=0 >>
     18:30:00 up 10 days,  2:45,  0 users,  load average: 0.00, 0.01, 0.05
     
     server2 | CHANGED | rc=0 >>
     18:30:00 up 5 days,  3:20,  0 users,  load average: 0.02, 0.03, 0.05

2. Memory Usage:

   • Check free memory on hosts.

   • Command: $ ansible all -a "free -m"

   • Sample Output:

     server1 | CHANGED | rc=0 >>
                   total        used        free      shared  buff/cache   available
     Mem:           1994         123        1671           0         199        1769
     Swap:          2047           0        2047
     
     server2 | CHANGED | rc=0 >>
                   total        used        free      shared  buff/cache   available
     Mem:           1994         124        1670           0         199        1768
     Swap:          2047           0        2047

3. Create a Unix User:

   • Create a user named "myuser."

   • Command: $ ansible all -a "useradd myuser"

   • Sample Output:

     server1 | CHANGED | rc=0 >>
     (no output)
     
     server2 | CHANGED | rc=0 >>
     (no output)
     

(The user creation require root privillage in the managed nodes, if not the command will fail)

1. Check User ID (UID):

   • Verify the user ID for "myuser."

   • Command: $ ansible all -a "id myuser"

   • Sample Output:

     server1 | CHANGED | rc=0 >>
     uid=1001(myuser) gid=1001(myuser) groups=1001(myuser)
     
     server2 | CHANGED | rc=0 >>
     uid=1001(myuser) gid=1001(myuser) groups=1001(myuser)

2. Create a Directory Using the File Module:

   • Create a directory named "/etc/some_directory."

   • Command: $ ansible all -m file -a "path=/etc/some_directory state=directory mode=0755"

   • Note: The Ansible file module is used to manage files and directories. It allows you to create, delete, modify permissions, copy, touch, or manipulate file ownership.

Note: (We used an Ansible module named file. We will discuss modules later in the session. If you want to know more about the file module,)please refer to the official documentation.