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Getting Started With Ansible - Part Twelve

This is in continuation of the articles of the series “Learning Ansible”. In the previous article, we saw templates and their real-life use case.
 
Here, in this article, we will be learning the below topics,
  • Roles in Ansible.
  • Ansible Galaxy
A playbook contains a lot of things like tasks, handlers, templates, files, variables, etc. So, over a period of time, it grows in size and then it becomes really difficult to understand.
 
For example, when you have songs on your laptop then you categorize them according to language, mood, artists, etc. So, suppose you want to listen to Hindi songs; you can directly go to that directory and look for your song.
 
Similarly, as Ansible believes in SIMPLICITY, we have something called Roles.
 
We can have a different role like MySQL, handlers, build server and these roles will have separate YAML files for execution.
 
So, we will create a directory structure for our playbook and we will distribute everything like tasks, handlers, etc. inside our playbook into different folders.
 
Ansible

So, we will create a directory with name roles and under that, we will create a subdirectory for the role names and that directory will have further directories, for example tasks and that directory will have main.yml and it will just have a list of tasks.
 
Similarly, vars/main.yml will contains only variables.

Templates will contain your templates.

Files will contain your file which we can push using the copy module.

Handlers/main.yml will contain only handlers.

Meta/main.yml will contain the metadata.

Defaults/main.yml will also contain variables but vars/main.yml have higher priority as compared to defaults/main.yml

Now let’s get started and write our playbook with the roles and after that, we will create the directory structure.
 
First, install the tree with the below command so that we can see the roles directory structure.
  1. sudo snap install tree  
Then, create a directory with the name roles and run the below commands.
  1. mkdir roles  
Ansible
  1. cd roles   
  2. ansible-galaxy inti post_setup  
Ansible
This command will generate the directory structure for the roles and will create a new role named post_setup (this name can be anything).
 
Then run tree command. 
  1. tree  
Ansible
We can see that our directory structure for roles has been generated.
 
Ansible
The next step is really simple; we can see that as of now our playbook looks something like below.
 
Our Existing Playbook Code 
  1. ---                                                                                                                                                                                                                   
  2.                                                                                                                                                                                                                       
  3. - name: Deploying NTP Service                                                                                                                                                                                         
  4.   hosts: all                                                                                                                                                                                                          
  5.   become: yes                                                                                                                                                                                                         
  6.   tasks:                                                                                                                                                                                                              
  7.           - name: Install packages on RedHat OS                                                                                                                                                                       
  8.             yum:                                                                                                                                                                                                      
  9.               name: "{{item}}"                                                                                                                                                                                        
  10.               state: present                                                                                                                                                                                          
  11.             loop:                                                                                                                                                                                                     
  12.               - ntp                                                                                                                                                                                                   
  13.               - unzip                                                                                                                                                                                                 
  14.               - git                                                                                                                                                                                                   
  15.               - wget                                                                                                                                                                                                  
  16.               - zip                                                                                                                                                                                                   
  17.             when: ansible_os_family == "RedHat"                                                                                                                                                                       
  18.                                                                                                                                                                                                                       
  19.           - name: Install packages on Debian OS                                                                                                                                                                       
  20.             apt:                                                                                                                                                                                                      
  21.               name: "{{item}}"                                                                                                                                                                                        
  22.               state: present                                                                                                                                                                                          
  23.             loop:                                                                                                                                                                                                     
  24.               - ntp                                                                                                                                                                                                   
  25.               - unzip                                                                                                                                                                                                 
  26.               - git                                                                                                                                                                                                   
  27.               - wget                                                                                                                                                                                                  
  28.               - zip                                                                                                                                                                                                   
  29.             when: ansible_os_family == "Debian"                                                                                                                                                                       
  30.                                                                                                                                                                                                                       
  31.           - name: Start and Enable NTP service in RedHat OS                                                                                                                                                           
  32.             service:                                                                                                                                                                                                  
  33.               name: ntpd                                                                                                                                                                                              
  34.               state: started                                                                                                                                                                                          
  35.               enabled: yes                                                                                                                                                                                            
  36.             when: ansible_os_family == "RedHat"                                                                                                                                                                       
  37.                                                                                                                                                                                                                       
  38.           - name: Start and Enable NTP service in Debian OS                                                                                                                                                           
  39.             service:                                                                                                                                                                                                  
  40.               name: ntp                                                                                                                                                                                               
  41.               state: started                                                                                                                                                                                          
  42.               enabled: yes                                                                                                                                                                                            
  43.             when: ansible_os_family == "Debian"                                                                                                                                                                       
  44.                                                                                                                                                                                                                       
  45.           - name: Deploy the NTP configuration file for Debian OS                                                                                                                                                     
  46.             template:                                                                                                                                                                                                 
  47.               src: templates/ntp_debian.j2                                                                                                                                                                            
  48.               dest: /etc/ntp.conf                                                                                                                                                                                     
  49.               backup: yes                                                                                                                                                                                             
  50.             when: ansible_os_family == "Debian"                                                                                                                                                                       
  51.             notify:                                                                                                                                                                                                   
  52.                 - Restart NTP service in Debian OS                                                                                                                                                                    
  53.                                                                                                                                                                                                                       
  54.                                                                                                                                                                                                                       
  55.           - name: Deploy the NTP configuration file for RedHat OS                                                                                                                                                     
  56.             template:                                                                                                                                                                                                 
  57.               src: templates/ntp_redhat.j2                                                                                                                                                                            
  58.               dest: /etc/ntp.conf                                                                                                                                                                                     
  59.               backup: yes                                                                                                                                                                                             
  60.             when: ansible_os_family == "RedHat"                                                                                                                                                                       
  61.             notify:                                                                                                                                                                                                   
  62.                 - Restart NTP service in RedHat OS                                                                                                                                                                    
  63.                                                                                                                                                                                                                       
  64.   handlers:                                                                                                                                                                                                           
  65.           - name: Restart NTP service in RedHat OS                                                                                                                                                                    
  66.             service:                                                                                                                                                                                                  
  67.               name: ntpd                                                                                                                                                                                              
  68.               state: restarted                                                                                                                                                                                        
  69.             when: ansible_os_family == "RedHat"                                                                                                                                                                       
  70.                                                                                                                                                                                                                       
  71.           - name: Restart NTP service in Debian OS                                                                                                                                                                    
  72.             service:                                                                                                                                                                                                  
  73.               name: ntp                                                                                                                                                                                               
  74.               state: restarted                                                                                                                                                                                        
  75.             when: ansible_os_family == "Debian"   

Taking out Tasks from Playbook

 
We can see there are lots of tasks and handlers. So now, we just need to copy things from here and paste them in the respective location under roles folder.
 
So first, we will copy all the tasks from our existing playbook shown above ntp_playbook.yml and will move all the tasks to roles/post_setup/tasks/main.yml file.
 
Open the file with the below command.
  1. vim roles/post_setup/tasks/main.yml  
and paste all tasks.
 
Now, our updated roles/post_setup/tasks/main.yml file looks like below.
  1. ---                                                                                                                                                                                                                   
  2. - name: Install packages on RedHat OS                                                                                                                                                                                 
  3.   yum:                                                                                                                                                                                                                
  4.     name: "{{item}}"                                                                                                                                                                                                  
  5.     state: present                                                                                                                                                                                                    
  6.   loop:                                                                                                                                                                                                               
  7.     - ntp                                                                                                                                                                                                             
  8.     - unzip                                                                                                                                                                                                           
  9.     - git                                                                                                                                                                                                             
  10.     - wget                                                                                                                                                                                                            
  11.     - zip                                                                                                                                                                                                             
  12.   when: ansible_os_family == "RedHat"                                                                                                                                                                                 
  13.                                                                                                                                                                                                                       
  14. - name: Install packages on Debian OS                                                                                                                                                                                 
  15.   apt:                                                                                                                                                                                                                
  16.     name: "{{item}}"                                                                                                                                                                                                  
  17.     state: present                                                                                                                                                                                                    
  18.   loop:                                                                                                                                                                                                               
  19.     - ntp                                                                                                                                                                                                             
  20.     - unzip                                                                                                                                                                                                           
  21.     - git                                                                                                                                                                                                             
  22.     - wget                                                                                                                                                                                                            
  23.     - zip                                                                                                                                                                                                             
  24.   when: ansible_os_family == "Debian"                                                                                                                                                                                 
  25.                                                                                                                                                                                                                       
  26. - name: Start and Enable NTP service in RedHat OS                                                                                                                                                                     
  27.   service:                                                                                                                                                                                                            
  28.     name: ntpd                                                                                                                                                                                                        
  29.     state: started                                                                                                                                                                                                    
  30.     enabled: yes                                                                                                                                                                                                      
  31.   when: ansible_os_family == "RedHat"                                                                                                                                                                                 
  32.                                                                                                                                                                                                                       
  33. - name: Start and Enable NTP service in Debian OS                                                                                                                                                                     
  34.   service:                                                                                                                                                                                                            
  35.     name: ntp                                                                                                                                                                                                         
  36.     state: started                                                                                                                                                                                                    
  37.     enabled: yes                                                                                                                                                                                                      
  38.   when: ansible_os_family == "Debian"                                                                                                                                                                                 
  39.                                                                                                                                                                                                                       
  40. - name: Deploy the NTP configuration file for Debian OS                                                                                                                                                               
  41.   template:                                                                                                                                                                                                           
  42.     src: templates/ntp_debian.j2                                                                                                                                                                                                
  43.     dest: /etc/ntp.conf                                                                                                                                                                                               
  44.     backup: yes                                                                                                                                                                                                       
  45.   when: ansible_os_family == "Debian"                                                                                                                                                                                 
  46.   notify:                                                                                                                                                                                                             
  47.       - Restart NTP service in Debian OS                                                                                                                                                                              
  48.                                                                                                                                                                                                                       
  49.                                                                                                                                                                                                                       
  50. - name: Deploy the NTP configuration file for RedHat OS                                                                                                                                                               
  51.   template:                                                                                                                                                                                                           
  52.     src: templates/ntp_redhat.j2                                                                                                                                                                                                
  53.     dest: /etc/ntp.conf                                                                                                                                                                                               
  54.     backup: yes                                                                                                                                                                                                       
  55.   when: ansible_os_family == "RedHat"                                                                                                                                                                                 
  56.   notify:                                                                                                                                                                                                             
  57.       - Restart NTP service in RedHat OS   

Taking out Handlers from Playbook


Similarly, take all handlers from ntp_playbook.yml and move them to roles/post_setup/handlers/main.yml file.
 
Open the file with the below command.
  1. vim roles/post_setup/handlers/main.yml 
Paste all handlers there and replace all the extra space on the left side like below.
 
Ansible

Below is the updated roles/post_setup/handlers/main.yml file.
  1. ---                                                                                                                                                                                                                   
  2. - name: Restart NTP service in RedHat OS                                                                                                                                                                              
  3.   service:                                                                                                                                                                                                            
  4.     name: ntpd                                                                                                                                                                                                        
  5.     state: restarted                                                                                                                                                                                                  
  6.   when: ansible_os_family == "RedHat"                                                                                                                                                                                 
  7.                                                                                                                                                                                                                       
  8. - name: Restart NTP service in Debian OS                                                                                                                                                                              
  9.   service:                                                                                                                                                                                                            
  10.     name: ntp                                                                                                                                                                                                         
  11.     state: restarted                                                                                                                                                                                                  
  12.   when: ansible_os_family == "Debian"   

Taking out Variables from Group_vars/all

 
Next, take out the variables from the group_vars/all file ( Delete the variables in group_vars/all file) and place them inside roles/post_setup/defaults/main.yml file.
 
Below is the updated roles/post_setup/defaults /main.yml file.
  1. ---   
  2. ntp0: '0.in.pool.ntp.org'   
  3. ntp1: '1.in.pool.ntp.org'   
  4. ntp2: '2.in.pool.ntp.org'   
  5. ntp3: '3.in.pool.ntp.org'   
We have put the variables in the defaults directory as they have the lowest priority.

The main reason for using roles Is reusability and we can use roles across organization across different projects. So different projects may have their data centers at different locations and they may be using different cloud providers as well. So, they are not necessarily going to use your values they may overwrite the values and thus these values defined here will act as the default values.
 

Taking out templates from Templates directory

 
We can move our template files with .j2 extension using the below command.
  1. mv templates/* roles/post_setup/templates/ 
And we will also need to modify the tasks in roles/post_setup/tasks/main.yml as now ansible will automatically pick up the template so we don’t need to specify the full path for our ntp_debian.j2 and ntp_redhat.j2 template files.

Below is the updated roles/post_setup/tasks/main.yml task file.
  1. ---                                                                                                                                                                                                                   
  2. - name: Install packages on RedHat OS                                                                                                                                                                                 
  3.   yum:                                                                                                                                                                                                                
  4.     name: "{{item}}"                                                                                                                                                                                                  
  5.     state: present                                                                                                                                                                                                    
  6.   loop:                                                                                                                                                                                                               
  7.     - ntp                                                                                                                                                                                                             
  8.     - unzip                                                                                                                                                                                                           
  9.     - git                                                                                                                                                                                                             
  10.     - wget                                                                                                                                                                                                            
  11.     - zip                                                                                                                                                                                                             
  12.   when: ansible_os_family == "RedHat"                                                                                                                                                                                 
  13.                                                                                                                                                                                                                       
  14. - name: Install packages on Debian OS                                                                                                                                                                                 
  15.   apt:                                                                                                                                                                                                                
  16.     name: "{{item}}"                                                                                                                                                                                                  
  17.     state: present                                                                                                                                                                                                    
  18.   loop:                                                                                                                                                                                                               
  19.     - ntp                                                                                                                                                                                                             
  20.     - unzip                                                                                                                                                                                                           
  21.     - git                                                                                                                                                                                                             
  22.     - wget                                                                                                                                                                                                            
  23.     - zip                                                                                                                                                                                                             
  24.   when: ansible_os_family == "Debian"                                                                                                                                                                                 
  25.                                                                                                                                                                                                                       
  26. - name: Start and Enable NTP service in RedHat OS                                                                                                                                                                     
  27.   service:                                                                                                                                                                                                            
  28.     name: ntpd                                                                                                                                                                                                        
  29.     state: started                                                                                                                                                                                                    
  30.     enabled: yes                                                                                                                                                                                                      
  31.   when: ansible_os_family == "RedHat"                                                                                                                                                                                 
  32.                                                                                                                                                                                                                       
  33. - name: Start and Enable NTP service in Debian OS                                                                                                                                                                     
  34.   service:                                                                                                                                                                                                            
  35.     name: ntp                                                                                                                                                                                                         
  36.     state: started                                                                                                                                                                                                    
  37.     enabled: yes                                                                                                                                                                                                      
  38.   when: ansible_os_family == "Debian"                                                                                                                                                                                 
  39.                                                                                                                                                                                                                       
  40. - name: Deploy the NTP configuration file for Debian OS                                                                                                                                                               
  41.   template:                                                                                                                                                                                                           
  42.     src: ntp_debian.j2                                                                                                                                                                                                
  43.     dest: /etc/ntp.conf                                                                                                                                                                                               
  44.     backup: yes                                                                                                                                                                                                       
  45.   when: ansible_os_family == "Debian"                                                                                                                                                                                 
  46.   notify:                                                                                                                                                                                                             
  47.       - Restart NTP service in Debian OS                                                                                                                                                                              
  48.                                                                                                                                                                                                                       
  49.                                                                                                                                                                                                                       
  50. - name: Deploy the NTP configuration file for RedHat OS                                                                                                                                                               
  51.   template:                                                                                                                                                                                                           
  52.     src: ntp_redhat.j2                                                                                                                                                                                                
  53.     dest: /etc/ntp.conf                                                                                                                                                                                               
  54.     backup: yes                                                                                                                                                                                                       
  55.   when: ansible_os_family == "RedHat"                                                                                                                                                                                 
  56.   notify:                                                                                                                                                                                                             
  57.       - Restart NTP service in RedHat OS   
So, we can see that we have just given the name of template file in the template module that we have used.

Now as we have moved our tasks, handlers, variables, and templates to the respective locations in roles directory, so now its time to update our playbook ntp_playbook.yml.
 
Below is the updated playbook ntp_playbook.yml.
  1. ---   
  2. - name: Deploying NTP Service   
  3. hosts: all   
  4. become: yes   
  5. roles:   
  6.    - post_setup  
Here, we just gave the role name and we can see that all the tasks and handlers have been removed.
 
Now, let’s run and see the output if it works 😊.
 
OUTPUT
 
Ansible
 
We can see that our tasks defined in post-setup roles got executed successfully.
 
After all that stuff now, it’s time to see something easy and relaxing which will ease out your work a lot.
 

Ansible Galaxy


Ansible Galaxy refers to the Galaxy website where users can share roles, and to a command-line tool for installing, creating and managing roles.
 
By now we have been writing our playbook on our own for the services like NTP, MySQL, Tomcat which are very popular, and they are already written playbooks for them. So instead of writing, we can reuse them.
 
It is a community repository and all the roles are available here which can be used. For example, there is a role called Java and if we want to install java then we can make use of this link.
 
Ansible
It also shows the OS which it supports and on which OS this role can be installed.
 
So, we are now going to install java on all our servers. For that, we will run the below command.
 
ansible-galaxy install geerlingguy.java
 
Ansible
 
We can see that it has downloaded the role from GitHub and has installed the role in /home/ubuntu/.ansible/roles/ directory. We can also move this role to our locally created roles folder.

Now, it is time to update our playbook with the new role and run the playbook.
 
Below is the updated playbook ntp_playbook.yml,
  1. ---   
  2. - name: Deploying NTP Service   
  3. hosts: all   
  4. become: yes   
  5. roles:   
  6.    - post_setup   
  7.    - geerlingguy.java   
OUTPUT
 
Ansible

We can see that Java has been installed successfully on all the web servers and db server.
 

Summary

 
In this article, we have learned about the roles in Ansible and Ansible Galaxy. I hope you get to learn a lot of interesting things about ansible through the series “Learning Ansible”. Keep learning and if you want to learn more than follow the official documentation of ansible here.
 
I hope you find this article helpful. Stay tuned for more … Cheers!!

You can also check out some of my previous articles of the series “Learning Ansible” here,


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