Ansible for Beginners with exercises. Topics covered: modules, inventory, variables, loops, filters, conditionals, and register

1. Ansible Workshop

2. hello!
I am Arie Bregman
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3. What are we going to do today?
● Learn what is Ansible
● Do automation with Ansible
● Ask the instructor many question
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4. What is Ansible?
● IT Automation Tool
● Focuses on simplicity and ease-of-use
● Open Source
○ More than 4,000 contributors
○ More than 40,000 contributions
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5. Why using Ansible?
● “Why not simply use shell scripts?”
● “Why specifically Ansible and not Puppet or Chef or …?”
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6. Let’s install a package with a shell script
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YUM_CMD=$(which yum) # or dnf
APT_GET_CMD=$(which apt-get)
...
if [[ ! -z $YUM_CMD ]]; then
dnf install ntpdate
elif [[ ! -z $APT_GET_CMD ]]; then
apt-get install ntpdate
elif ...
...
else
echo "error can't install package ntpdate"
exit 1;
fi

7. Now let’s install the same package with Ansible
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- name: install ntpdate
package:
name: ntpdate
state: present
● Works on multiple distributions
● Readable
● Describes desired status rather than the action
This is called a
“task” in Ansible

8. Why specifically Ansible?
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● Python & SSH is all you need
● Simple to use
● Agentless
● Over 3300 modules!
● Great community

9. Time to have fun! but first, installation
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# Fedora, RHEL 8, CentOS 8
$ dnf install ansible -y
# For older releases, use yum instead
# Ubuntu
$ apt-get install ansible -y
# Verify you can ssh without using a password to the machine you’ll use
$ ssh x.x.x.x
# No? Then run the following
$ ssh-copy-id <user>@x.x.x.x

11. Inventory
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● The hosts/servers you manage with Ansible
● Types of inventory
○ Static
○ Dynamic
● Default inventory
○ /etc/ansible/hosts
We will define a static inventory

12. Update you inventory
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[remote]
x.x.x.x
$ sudo vi /etc/ansible/hosts
Let’s test it! :)
ansible remote -m ping
remote | SUCCESS => {
"changed": false,
"ping": "pong"
}
x.x.x.x [remote]
X.x.x.x ansible_user=vagrant
Or Or
Using this, you can
later reference in
Ansible multiple
servers with one
name

13. Write your first Playbook
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- hosts: remote
tasks:
- name: Create the file /tmp/x
file:
path: /tmp/x
state: touch
$ vi first_task.yml
* A playbooks is a collection
plays
* A play is a collection of tasks
running on a single or multiple
hosts

14. Run your first Playbook
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PLAY [remote] **************************************************
TASK [Gathering Facts] *****************************************
ok: [remote]
TASK [Create the file /tmp/x] **********************************
changed: [remote]
PLAY RECAP *****************************************************
remote : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0
$ ansible-playbook first_playbook.yml

15. Multiple Tasks
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- hosts: remote
tasks:
- name: Install the package htop
become: yes
package:
name: htop
state: present
- name: install the package python-routes
become: true
package:
name: python-routes
state: present
- hosts: webservers
tasks:
- name: Install the package htop
become: yes
package:
name: htop
state: present
- hosts: dbservers
tasks:
- name: install the package python-routes
become: root
package:
name: python-routes
state: present
Playbook
play
play

16. Exercise #1
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● Write a playbook which will:
○ Create the file /tmp/x
○ Create the file /tmp/y
○ Create the file /tmp/z
- hosts: [host or hosts group name]
tasks:
- name: [task name]
[module name]:
path: ...
state: ...
# Commands
ansible-playbook

17. What modules are there?
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$ ansible-doc <module_name>
$ ansible-doc file
$ ansible-doc -l
● List modules
● Information on specific module

18. ansible-doc format
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Module source code path
Module Description
Single option (Optional)

19. 19
Module Author and support
Examples ==
How to use the
module

20. Variables
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● Used for storing values you can reference multiple times in your
playbook, in different tasks
● It’s common to find them used in conditionals, loops, ...
- hosts: remote
vars:
file_path: /tmp/x
tasks:
- name: Create the file "{{ file_path }}"
file:
name: "{{ file_path }}"
state: touch

21. Loops
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● What if I need to create 10 files or install 30 package?
- hosts: remote
tasks:
- name: Create multiple files
file:
name: "{{ item }}"
state: touch
loop:
- /tmp/a
- /tmp/b
- /tmp/c

22. 22
PLAY [remote]
********************************************************************************************************
TASK [Gathering Facts]
************************************************************************************************
ok: [192.168.33.10]
TASK [add several users]
**************************************************************************************************
changed: [192.168.33.10] => (item=/tmp/a)
changed: [192.168.33.10] => (item=/tmp/b)
changed: [192.168.33.10] => (item=/tmp/c)
PLAY RECAP
************************************************************************************************************
192.168.33.10 : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0

23. Privileges
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● Some tasks can’t be executed by a regular user
○ Installing packages
○ Adding users
● The “become” directive helps with that
- hosts: remote
tasks:
- name: Install the package python
become: yes
package:
name: python
state: present
- hosts: remote
tasks:
- name: Install the package python
become: yes
become_user: luigi
file:
path: ~/stam_file
state: present

24. Exercise #2
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● Write a playbook which will:
○ Add the users
■ sarah, john, grace
○ Create the directories
■ /tmp/dir1 , /tmp/dir2, /tmp/dir3
# Commands
ansible-playbook
ansible-doc -l
ansible-doc <module_name>
# Directives
loop:
become:
become_user:
- hosts: remote
tasks:
- name: blip blop
file:
...
loop:
- ...

25. Facts
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ansible remote -m setup | less
...
"ansible_user_dir": "/home/vagrant",
"ansible_user_gecos": "",
"ansible_user_gid": 1000,
"ansible_user_id": "vagrant",
"ansible_user_shell": "/bin/bash",
"ansible_user_uid": 1000,
"ansible_userspace_architecture": "x86_64",
"ansible_userspace_bits": "64",
"ansible_virtualization_role": "guest",
"ansible_virtualization_type": "virtualbox",
...

26. Conditionals
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● Run task only when certain condition is met
- hosts: remote
tasks:
- name: Install apache httpd
become: yes
apt:
name: apache2
state: present
when: ansible_facts['distribution'] == "Ubuntu"

27. Conditionals: AND
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- hosts: remote
tasks:
- name: Install apache httpd
become: yes
apt:
name: apache2
state: present
when:
- ansible_facts['distribution'] in ['CentOS', 'RedHat']
- my_var < 6
- install_apache

28. Conditionals: OR
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- hosts: remote
tasks:
- name: Install apache httpd
become: yes
apt:
name: apache2
state: present
when: ansible_facts['distribution'] == "Ubuntu" or ansible_facts['distribution'] == "Suse"

29. 29
{{ [32, 3, 5, 121, 6, 7] | max }}
Filters
● Transformation of data
{{ [32, 3, 5, 121, 6, 7] | min }}
{{ [32, 3, 5, 121, 6, 7] | random }}
{{ some_path | dirname }}
{{ some_string | quote }}

30. 30
- hosts: remote
tasks:
- name: Create multiple files
file:
name: "{{ item }}"
state: touch
loop: “{{ files_list | default([]) }}” What is the result of
the task?
OK? Changed?
Skipped?
● Also useful for dealing with undefined variables

31. Exercise #3
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● Write a playbook which will:
○ Install the package htop only if the major version of the
operating system is 14
○ Install the package netcat only if the major version of the
operating system is 16
○ Add one random user of the following
■ [‘ed’, ‘eddy’, ‘eddie’]
# Commands
ansible-playbook
ansible-doc -l
ansible-doc <module_name>
ansible remote -m setup | less

32. AD-HOC
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● Run tasks without writing playbooks
● For quick and non-repeating changes
ansible [hosts_pattern] -m [module_name] -a “[module options]”

33. AD-HOC Example
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ansible remote -m file -a "name=/tmp/ad-hoc state=touch"
192.168.33.10 | CHANGED => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python"
},
"changed": true,
"dest": "/tmp/ad-hoc",
"gid": 1000,
"group": "vagrant",
"mode": "0664",
"owner": "vagrant",
"size": 0,
"state": "file",
"uid": 1000
}

34. Exercise #4
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● Create locally a file with the content
○ “I came here from a far far server”
● Using ad-hoc commands:
○ Add a user called “mario”
○ Run the service “cron” (Ubuntu) or “crond” (RHEL, Fedora)
○ Copy the file you create to the remote server
# Commands
ansible-playbook
ansible-doc -l
ansible-doc <module_name>
ansible remote -m setup | less
ansible remote -m module -a “...”
ansible [hosts_pattern] -m [module_name] -a “[module options]”

35. Command & Shell modules
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● “I want to run a customized script on a remote host”
● “I’m unable to find a module for what I need”
● Solution
○ command or shell module
name: Get blipblop version
become: yes
command: "rpm -q --qf %{VERSION} blipblop"
register: blipblop_rpm_version

36. Register Result
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● By registering the result of a task we can “connect” between tasks
- name: Get blipblop version
become: yes
command: "rpm -q --qf %{VERSION} blipblop"
register: blipblop_rpm_version
- name: Get blipblop version
become: yes
shell: |
echo “blip blop begin”
ls -l
echo “blip blop end”
when: blipblop_rpm_version.stdout == “1.2.3”

37. Register: Another Example
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● Configure an app and run it only if configuration was successful
- name: configure X app
command: configure
args:
chdir: /x_app
register: x_app_config
- name: run X app
command: run
args:
chdir: /x_app
when: x_app_config.rc == 0

38. Register: One More Example
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● Run until return code is 0
- name: run some_command
command: some_command
register: result
until: result.rc == 0
retries: 5

39. Exercise #5
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● Write the following playbook:
○ Download the file
https://gist.github.com/corysimmons/8b94c08421dec18bbaa4
○ If the download was successful, log the message “I managed to
download file with Ansible. So excited…”
# Commands
ansible-playbook
ansible-doc -l
ansible-doc <module_name>
ansible remote -m setup | less
ansible remote -m module -a “...”
# Directives
loop:
when:
become: become_user:
args:
until:
# Variables
{{ x }}
{{ x | default(“”) }}

40. Summary
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# Commands
ansible-playbook
ansible-doc -l
ansible-doc <module_name>
ansible remote -m setup | less
ansible remote -m module -a “...”
# Variables
{{ x }}
{{ x | default(“”) }}
# Directives
loop:
when:
become:
become_user
args:
until:

41. Next Steps (Suggestion)
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● Blocks
● Ansible Roles
● Dynamic Inventory
● Error Handling
● Tests

42. thanks!
Any questions?
You can contact me at
linkedin@abregman
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43. Credits
Special thanks to all the people who made and released
these awesome resources for free:
✘ Presentation template by SlidesCarnival
✘ Photographs by Unsplash
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