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README.md

Ad Hoc Commands, Templates and Variables

You have finished the lab already. But it doesn’t have to end here. We prepared some slightly more advanced bonus labs for you to follow through if you like. So if you are done with the labs and still have some time, here are some more labs for you:

Step 1 - Bonus Lab: Ad Hoc Commands

Create a new user "testuser" on node1 and node3 with a comment using an ad hoc command, make sure that it is not created on node2!

  • Find the parameters for the appropriate module using ansible-doc user (leave with q)

  • Use an Ansible ad hoc command to create the user with the comment "Test D User"

  • Use the "command" module with the proper invocation to find the userid

  • Delete the user and its directories, then check that the user has been deleted

Tip

Remember privilege escalation…​

Warning

Solution below!

Your commands could look like these:

[user@control ansible-files]$ ansible-doc -l | grep -i user
[user@control ansible-files]$ ansible-doc user
[user@control ansible-files]$ ansible node1,node3 -m user -a "name=testuser comment='Test D User'" -b
[user@control ansible-files]$ ansible node1,node3 -m command -a " id testuser" -b
[user@control ansible-files]$ ansible node2 -m command -a " id testuser" -b
[user@control ansible-files]$ ansible node1,node3 -m user -a "name=testuser state=absent remove=yes" -b
[user@control ansible-files]$ ansible web -m command -a " id testuser" -b

Step 2 - Bonus Lab: Templates and Variables

You have learned the basics about Ansible templates, variables and handlers. Let’s combine all of these.

Instead of editing and copying httpd.conf why don’t you just define a variable for the listen port and use it in a template? Here is your job:

  • Define a variable listen_port for the web group with the value 8080 and another for node2 with the value 80 using the proper files.

  • Copy the httpd.conf file into the template httpd.conf.j2 that uses the listen_port variable instead of the hard-coded port number.

  • Write a Playbook that deploys the template and restarts Apache on changes using a handler.

  • Run the Playbook and test the result using curl.

Tip

Remember the group_vars and host_vars directories? If not, refer to the chapter "Ansible Variables".

Warning

Solution below!

Define the variables:

Add this line to group_vars/web:

listen_port: 8080

Add this line to host_vars/node2:

listen_port: 80

Prepare the template:

  • Copy httpd.conf to httpd.conf.j2

  • Edit the "Listen" directive in httpd.conf.j2 to make it look like this:

[...]
Listen {{ listen_port }}
[...]

Create the Playbook

Create a playbook called apache_config_tpl.yml:

---
- name: Apache httpd.conf
  hosts: web
  become: yes
  tasks:
  - name: Create Apache configuration file from template
    template:
      src: httpd.conf.j2
      dest: /etc/httpd/conf/httpd.conf
    notify:
        - restart apache
  handlers:
    - name: restart apache
      service:
        name: httpd
        state: restarted

Run and test

First run the playbook itself, then run curl against node1 with port 8080 and node2 with port 80.

[user@control ansible-files]$ ansible-playbook apache_config_tpl.yml
[...]
[user@control ansible-files]$ curl http://192.168.55.201:8080
<body>
<h1>This is a development webserver, have fun!</h1>
</body>
[user@control ansible-files]$ curl http://192.168.55.202:80
<body>
<h1>This is a production webserver, take care!</h1>
</body>

Click here to return to the Ansible for Red Hat Enterprise Linux Workshop