Creating roles

Creating Reusable Code

Chapter 5

Concepts

what is a role
when to create a role
how to create a role
Notifications and Handlers
Pre and Post Tasks
nesting of roles using include

why roles

Address Complexity

Reusability and Sharing

Modular Code

complexity

---
  - name: Base Configurations for ALL hosts
    hosts: prod:!app2
    become: true
    tasks:
      - name: create admin user
        user: name=admin state=present uid=5001

      - name: remove dojo
        user: name=dojo  state=absent

      - name: install tree
        package:  name=tree  state=present

      - name: install ntp
        package:  name=ntp   state=present

      - name: start ntp service
        service: name=ntpd state=started enabled=yes

  - name: App Server Configurations
    hosts: app
    become: true
    tasks:
      - name: create app user
        user: name=app state=present uid=5003

      - name: install git
        package:  name=git  state=present

playbook.yml

hosts definitions, properties, tasks all in one place

specific to one environment, can not be shared

```
difficult to reuse 
```

can quickly get out of control with increasing number of applications

modular approach

---
  - name: Base Configurations for ALL hosts
    hosts: all
    become: true
    tasks:
      - name: create admin user
        user: name=admin state=present uid=5001

      - name: remove dojo
        user: name=dojo  state=absent

      - name: install tree
        yum:  name=tree  state=present

      - name: install ntp
        yum:  name=ntp   state=present

      - name: start ntp service
        service: name=ntpd state=started enabled=yes

- name: App Server Configurations
  hosts: app
  become: true
  tasks:
    - name: create app user
      user: name=app state=present uid=5003

    - name: install git
      yum:  name=git  state=present

roles

base

apache

php

playbook.yml

Strategy : Move code related to each application/feture to its own place, call it a role

simplification

roles

base

apache

---
  - name: Base Configurations for ALL hosts
    hosts: all
    become: true
    roles:
     - base

- name: App Server Configurations
  hosts: app
  become: true
  roles:
     - apache
     - php

php

playbook.yml

```
playbook is simplified
```
```
modular code 
```
```
reusable and sharable
```

before

---
  - name: Base Configurations for ALL hosts
    hosts: all
    become: true
    tasks:
      - name: create admin user
        user: name=admin state=present uid=5001

      - name: remove dojo
        user: name=dojo  state=absent

      - name: install tree
        yum:  name=tree  state=present

      - name: install ntp
        yum:  name=ntp   state=present

      - name: start ntp service
        service: name=ntpd state=started enabled=yes

- name: App Server Configurations
  hosts: app
  become: true
  tasks:
    - name: create app user
      user: name=app state=present uid=5003

    - name: install git
      yum:  name=git  state=present

---
  - name: Base Configurations for ALL hosts
    hosts: all
    become: true
    roles:
     - base

- name: App Server Configurations
  hosts: app
  become: true
  roles:
     - apache
     - php

after

what

A Role is a package which contains tasks which take action along with supporting entities such as handlers, properties, files, tests and metadata

What is a Role ?

Anatomy of a role

roles/
└── starter
    ├── defaults
    │   └── main.yml
    ├── files
    ├── handlers
    │   └── main.yml
    ├── meta
    │   └── main.yml
    ├── README.md
    ├── tasks
    │   └── main.yml
    ├── templates
    ├── tests
    │   ├── inventory
    │   └── test.yml
    └── vars
        └── main.yml

tasks

defaults

vars

files

templates

handlers

tests

meta

actions to take , using modules

default properties/vars

role specific vars

static files to be copied to nodes

files generated dynamically

actions to take on events

ansible tests

role meta data

when

1 : 1

Role

App

Feature

When to create a a Role ?

code organization strategies

Lets look at the strategies to organize the code better

code organization strategies

load balancers

app servers

db servers

apache

php

layers = inventory groups

code organization strategies

apache

php

roles

create roles for each app

haproxy

postgres

roles

code organization strategies

apache

php

play

create plays for each inventory group/layer

code organization strategies

apache

php

play

combine plays into a site wide playbook

site.yml

how

manual

There are two ways to create roles

Using

ansible-galaxy

Roles can be created by simply creating directories and files in certain order

A utility which lets you generate role scaffolding

ansible galaxy

https://galaxy.ansible.com/

ansible galaxy

a library of community contributed roles

servers as a source of reference to learn best practices

no need to reinvent the wheel. Resue and share roles

# ansible-galaxy init --init-path roles/ apache
- apache was created successfully
[root@ansible chap5]# tree roles/apache/
roles/apache/
├── defaults
│   └── main.yml
├── files
├── handlers
│   └── main.yml
├── meta
│   └── main.yml
├── README.md
├── tasks
│   └── main.yml
├── templates
├── tests
│   ├── inventory
│   └── test.yml
└── vars
    └── main.yml

8 directories, 8 files

Creating Roles with Galaxy

ansible-galaxy init --init-path roles/ apache

ansible-galaxy --help

# ansible-galaxy --help
Usage: ansible-galaxy [delete|import|info|init|install|list|login|remove|search|setup] [--help] [options] ...

Options:
  -h, --help     show this help message and exit
  -v, --verbose  verbose mode (-vvv for more, -vvvv to enable connection
                 debugging)
  --version      show program's version number and exit

seeking help

creating apache role

ge

Creating apache Role

ge

```
install httpd package
```

centrally manage httpd.conf   and copy it to all nodes

```
start httpd service
```

whenever apache configs are updated, relevant service should be  automatically restarted

Create a role for installing and configuration apache web server on CentOS platform which will,

Problem Statement

ge

cd  chap6

mkdir roles

ansible-galaxy init --offline --init-path=roles  apache

Lets begin by creating a scaffolding (directory structure) for apache role

validating

# ansible-galaxy init --init-path roles/ apache
- apache was created successfully
[root@ansible chap5]# tree roles/apache/
roles/apache/
├── defaults
│   └── main.yml
├── files
├── handlers
│   └── main.yml
├── meta
│   └── main.yml
├── README.md
├── tasks
│   └── main.yml
├── templates
├── tests
│   ├── inventory
│   └── test.yml
└── vars
    └── main.yml

8 directories, 8 files

ge

tree roles/

mapping ACTIONS to MODULES

install httpd

copy configs
and html docs

start httpd service

actions

modules

yum or apt

service

copy

Lets now come up with the actions that we would take to achieve desired state, and start mapping it to ansible modules

writing tasks

ge

We need to start defining actions and its desired state using tasks
tasks directory in roles comes with main.yml as a default task file
all actions can be defined in main.yml
however, we will create individual tasks for each action for fine grained control
and include it from main.yml

roles

apache

tasks

main.yml

install.yml

config.yml

service.yml

File: roles/apache/tasks/install.yml

---
  - name: install apache web server
    yum:
      name: httpd
      state: installed

Installing a package

ge

File: roles/apache/tasks/service.yml

---
  - name: start apache webserver
    service:
      name: httpd
      state: started
      enabled: true

starting a service

ge

File: roles/apache/tasks/main.yml

---
# tasks file for apache
  - import_tasks: install.yml
  - import_tasks: service.yml

writing main task

ge

when you call a role from playbook, it includes only main.yml task file

if you create additional task files, the only way to have those called is by including in main.yml

lets include install.yml and service.yml in main.yml for apache role

File: app.yml

---
  - hosts: app
    become: true
    roles:
      - apache

creating playbook for app

ge

As per our strategy, we are going to create a playbook for each layer

lets begin by writing app.yml for app servers

app.yml maps app servers to apply apache role

apache role will in turns point to main.yml

main.yml will then execute all included tasks from install.yml and start.yml

roles

apache

tasks

main.yml

install.yml

service.yml

root@control:/workspace/chap6# ansible-playbook app.yml                                         
                                                                                                
PLAY [app] *********************************************************************                
                                                                                                
TASK [setup] *******************************************************************                
ok: [app1]                                                                                      
ok: [app2]                                                                                      
                                                                                                
TASK [apache : Install Apache...] **********************************************                
changed: [app1]                                                                                 
changed: [app2]                                                                                 
                                                                                                
TASK [apache : Starting Apache...] *********************************************                
changed: [app2]                                                                                 
changed: [app1]                                                                                 
                                                                                                
PLAY RECAP *********************************************************************                
app1                       : ok=3    changed=2    unreachable=0    failed=0                     
app2                       : ok=3    changed=2    unreachable=0    failed=0

  ansible-playbook app.yml

Apply playbook for app

ge

root@control:/workspace/chap6# ansible app -b -a "service httpd status"                            
app2 | SUCCESS | rc=0 >>                                                                        
httpd (pid  3565) is running...                                                                 
                                                                                                
app1 | SUCCESS | rc=0 >>                                                                        
httpd (pid  3616) is running...

ansible app -b -a "which httpd"

Validate

ge

root@control:/workspace/chap6# ansible app -b -a "which httpd"                                     
app2 | SUCCESS | rc=0 >>                                                                        
/usr/sbin/httpd                                                                                 
                                                                                                
app1 | SUCCESS | rc=0 >>                                                                        
/usr/sbin/httpd

ansible app -b -a "service httpd status"

roles

apache

tasks

main.yml

install.yml

service.yml

files

httpd.conf

config.yml

in addition to installing and starting services, we also need to copy configuration file for apache

to manage centrally,  files are stored in its own dedicated files  directory inside roles

in addition, tasks to copy the  files from inside roles to appropriate destination need to be created. Lets write  config.yml  to do this

which will then be added to main.yml just like other two task files we created earlier

managing files

add files

ge

To simplify your work, httpd.conf has been given in the helper directory inside workspace

cp helper/httpd.conf roles/apache/files/

copy file to roles/apache/files

write tasks to copy files

ge

Lets now create config.yml to

---
  - name: copy over httpd configs
    copy:
      src: httpd.conf
      dest: /etc/httpd.conf
      owner: root
      group: root
      mode: 0644

path: roles/apache/tasks/config.yml

restarting service on config change

ge

Config File

~~port = 80~~

port = 8080

Service

restart

notify

handler

adding a handler

ge

roles

apache

tasks

main.yml

install.yml

start.yml

files

httpd.conf

index.html

config.yml

handlers

main.yml

just like tasks and files, handlers have their own dedicated directory

inside which you may already find main.yml. You could add handler to restart apache here

handler will get triggered only when notified

adding a handler

ge

---
# handlers file for apache
  - name: Restart apache service
    service: name=httpd state=restarted

path: roles/apache/handlers/main.yml

adding notification

ge

To notification, update config.yml

---
  - name: copy over httpd configs
    copy:
      src: httpd.conf
      dest: /etc/httpd.conf
      owner: root
      group: root
      mode: 0644
    notify: Restart apache service

path: roles/apache/tasks/config.yml

run playbook

ge

root@control:/workspace/chap6# ansible-playbook app.yml                        
                                                                               
PLAY [app:!app2] **************************************************************
*                                                                              
                                                                               
TASK [setup] ******************************************************************
*                                                                              
ok: [app1]                                                                     
                                                                               
TASK [apache : Install Apache...] *********************************************
*                                                                              
ok: [app1]                                                                     
                                                                               
TASK [apache : Starting Apache...] ********************************************
*                                                                              
ok: [app1]                                                                     
                                                                               
PLAY RECAP ********************************************************************
*                                                                              
app1                       : ok=3    changed=0    unreachable=0    failed=0

ansible-playbook app.yml

```
Were the files copied ? 
```

Was the service restarted as a result of config file updates ?

```
Create a php role
```

add tasks to install php and php-mysql packages

Exercise: Role to install PHP

copy following contents to /var/www/html/info.php

<?php
  phpinfo();  
?>

Send a notification to restart apache after installing the packages and copying the file

validate by visiting http://IPADDRESS:91/info.php

```
Create a Systems Role for common tasks
```

Move all tasks  in the systems.yml to this role.

Define role nesting with dependencies/meta-data

```
Create Site Wide Playbook
```

Exercise : Systems Role and Sitewide Playbook

1

Update httpd.conf and change some configuration parameters.

Validate the service restarts on configuration updates by applying the sitewide playbook.

Exercise  : Update Apache Configs

Creating roles

Concepts

what is a role

when to create a role

how to create a role

Notifications and Handlers

Pre and Post Tasks

nesting of roles using include

why roles

complexity

modular approach

simplification

before

after

what

Anatomy of a role

when

1 : 1

code organization strategies

code organization strategies

code organization strategies

code organization strategies

code organization strategies

how

manual

Using

ansible galaxy

ansible galaxy

Creating Roles with Galaxy

seeking help

creating apache role

ge

Creating apache Role

ge

Problem Statement

ge

validating

ge

mapping ACTIONS to MODULES

actions

modules

writing tasks

ge

Installing a package

ge

starting a service

ge

writing main task

ge

creating playbook for app

ge

Apply playbook for app

ge

Validate

ge

managing files

add files

ge

write tasks to copy files

ge

restarting service on config change

ge

adding a handler

ge

adding a handler

ge

adding notification

ge

run playbook

ge

1