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 withq
) -
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 theweb
group with the value8080
and another fornode2
with the value80
using the proper files. -
Copy the
httpd.conf
file into the templatehttpd.conf.j2
that uses thelisten_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
andhost_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
tohttpd.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>
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