In Ansible, the role is the primary mechanism for breaking a playbook into multiple files. This simplifies writing complex playbooks, and it makes them easier to reuse. The breaking of playbook allows you to logically break the playbook into reusable components.

Each role is basically limited to a particular functionality or desired output, with all the necessary steps to provide that result either within that role itself or in other roles listed as dependencies.

Roles are not playbooks. Roles are small functionality which can be independently used but have to be used within playbooks. There is no way to directly execute a role. Roles have no explicit setting for which host the role will apply to.

Top-level playbooks are the bridge holding the hosts from your inventory file to roles that should be applied to those hosts.

Creating a New Role

The directory structure for roles is essential to create a new role.

Role Structure

Roles have a structured layout on the file system. The default structure can be changed but for now let us stick to defaults.

Each role is a directory tree in itself. The role name is the directory name within the /roles directory.

$ ansible-galaxy -h

Usage

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.

Creating a Role Directory

The above command has created the role directories.

$ ansible-galaxy init vivekrole
ERROR! The API server (https://galaxy.ansible.com/api/) is not responding, please try again later.
$ ansible-galaxy init --force --offline vivekrole
- vivekrole was created successfully

$ tree vivekrole/
vivekrole/
├── 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

Not all the directories will be used in the example and we will show the use of some of them in the example.

Utilizing Roles in Playbook

This is the code of the playbook we have written for demo purpose. This code is of the playbook vivek_orchestrate.yml. We have defined the hosts: tomcat-node and called the two roles – install-tomcat and start-tomcat.

The problem statement is that we have a war which we need to deploy on a machine via Ansible.

—

– hosts: tomcat-node

roles:

– {role: install-tomcat}

– {role: start-tomcat}

Contents of our directory structure from where we are running the playbook.

ansi 4

$ ls

ansible.cfg hosts roles vivek_orchestrate.retry vivek_orchestrate.yml

ansi 5

There is a tasks directory under each directory and it contains a main.yml. The main.yml contents of install-tomcat are −

—

#Install vivek artifacts
-
block:
- name: Install Tomcat artifacts
action: >
yum name = "demo-tomcat-1" state = present
register: Output
always:
- debug:
msg:
- "Install Tomcat artifacts task ended with message: {{Output}}"
- "Installed Tomcat artifacts - {{Output.changed}}"
The contents of main.yml of the start tomcat are −
#Start Tomcat
-
block:
- name: Start Tomcat
command: <path of tomcat>/bin/startup.sh"
register: output
become: true
always:
- debug:
msg:
- "Start Tomcat task ended with message: {{output}}"
- "Tomcat started - {{output.changed}}"

The advantage of breaking the playbook into roles is that anyone who wants to use the Install tomcat feature can call the Install Tomcat role.

Breaking a Playbook into a Role

If not for the roles, the content of the main.yml of the respective role can be copied in the playbook yml file. But to have modularity, roles were created.

Any logical entity which can be reused as a reusable function, that entity can be moved to role. The example for this is shown above

Ran the command to run the playbook.

-vvv option for verbose output – verbose output
$ cd vivek-playbook/
This is the command to run the playbook
$ sudo ansible-playbook -i hosts vivek_orchestrate.yml –vvv

—————————————————————–

———————————————————————–

Output

The generated output is as seen on the screen −

Using /users/demo/vivek-playbook/ansible.cfg as config file.
PLAYBOOK: vivek_orchestrate.yml *********************************************************
***********************************************************
1 plays in vivek_orchestrate.yml
PLAY [tomcat-node] **********************************************************************
******** *************************************************
TASK [Gathering Facts] *************************************************
****************************** *********************************************
Tuesday 21 November 2017  13:02:05 +0530 (0:00:00.056) 0:00:00.056 ******
Using module file /usr/lib/python2.7/sitepackages/ansible/modules/system/setup.py
<localhost> ESTABLISH LOCAL CONNECTION FOR USER: root
<localhost> EXEC /bin/sh -c 'echo ~ && sleep 0'
<localhost> EXEC /bin/sh -c '( umask 77 && mkdir -p "` echo
/root/.ansible/tmp/ansible-tmp-1511249525.88-259535494116870 `" &&
echo ansible-tmp-1511249525.88-259535494116870="`
echo /root/.ansible/tmp/ansibletmp-1511249525.88-259535494116870 `" ) && sleep 0'
<localhost> PUT /tmp/tmpPEPrkd TO
/root/.ansible/tmp/ansible-tmp-1511249525.88259535494116870/setup.py
<localhost> EXEC /bin/sh -c 'chmod u+x
/root/.ansible/tmp/ansible-tmp1511249525.88-259535494116870/
/root/.ansible/tmp/ansible-tmp-1511249525.88259535494116870/setup.py && sleep 0'
<localhost> EXEC /bin/sh -c '/usr/bin/python
/root/.ansible/tmp/ansible-tmp1511249525.88-259535494116870/setup.py; rm -rf
"/root/.ansible/tmp/ansible-tmp1511249525.88-259535494116870/" > /dev/null 2>&1 && sleep 0'
ok: [server1]
META: ran handlers
TASK [install-tomcat : Install Tomcat artifacts] ***********************************
***************************************************************
task path: /users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:5
Tuesday 21 November 2017  13:02:07 +0530 (0:00:01.515)       0:00:01.572 ******
Using module file /usr/lib/python2.7/sitepackages/ansible/modules/packaging/os/yum.py
<localhost> ESTABLISH LOCAL CONNECTION FOR USER: root
<localhost> EXEC /bin/sh -c 'echo ~ && sleep 0'
<localhost> EXEC /bin/sh -c '( umask 77 && mkdir -p "` echo
/root/.ansible/tmp/ansible-tmp-1511249527.34-40247177825302 `" && echo
ansibletmp-1511249527.34-40247177825302="` echo
/root/.ansible/tmp/ansible-tmp1511249527.34-40247177825302 `" ) && sleep 0'
<localhost> PUT /tmp/tmpu83chg TO
/root/.ansible/tmp/ansible-tmp-1511249527.3440247177825302/yum.py
<localhost> EXEC /bin/sh -c 'chmod u+x
/root/.ansible/tmp/ansible-tmp1511249527.34-40247177825302/
/root/.ansible/tmp/ansible-tmp-1511249527.3440247177825302/yum.py && sleep 0'
<localhost> EXEC /bin/sh -c '/usr/bin/python
/root/.ansible/tmp/ansible-tmp1511249527.34-40247177825302/yum.py; rm -rf
"/root/.ansible/tmp/ansible-tmp1511249527.34-40247177825302/" > /dev/null 2>
&1 && sleep 0'
changed: [server1] => {
"changed": true,
"invocation": {
"module_args": {
"conf_file": null,
"disable_gpg_check": false,
"disablerepo": null,
"enablerepo": null,
"exclude": null,
"install_repoquery": true,
"installroot": "/",
"list": null,
"name": ["demo-tomcat-1"],
"skip_broken": false,
"state": "present",
"update_cache": false,
"validate_certs": true
}
},
"msg": "",
"rc": 0,
"results": [
"Loaded plugins: product-id,
search-disabled-repos,
subscriptionmanager\nThis system is not registered to Red Hat Subscription Management.
You can use subscription-manager to register.\nResolving Dependencies\n-->
Running transaction check\n--->
Package demo-tomcat-1.noarch 0:SNAPSHOT-1 will be installed\n--> Finished Dependency
Resolution\n\nDependencies Resolved\n
\n================================================================================\n
Package Arch Version Repository
Size\n==================================================================\nInstalling:\n
demo-tomcat-1 noarch SNAPSHOT-1 demo-repo1 7.1 M\n\nTransaction
Summary\n==================================================================\nInstall  1
Package\n\nTotal download size: 7.1 M\nInstalled size: 7.9 M\nDownloading
packages:\nRunning transaction
check\nRunning transaction test\nTransaction test succeeded\nRunning transaction\n  Installing :
demotomcat-1-SNAPSHOT-1.noarch 1/1 \n  Verifying  :
demo-tomcat-1-SNAPSHOT-1.noarch 1/1 \n\nInstalled:\n
demo-tomcat-1.noarch 0:SNAPSHOT-1 \n\nComplete!\n"
]
}
TASK [install-tomcat : debug] **********************************************************
***************************************************************************
task path: /users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:11
Tuesday 21 November 2017  13:02:13 +0530 (0:00:06.757) 0:00:08.329 ******
ok: [server1] => {
"changed": false,
"msg": [
"Install Tomcat artifacts task ended with message: {
u'msg': u'', u'changed': True, u'results':
[u'Loaded plugins: product-id,
search-disabledrepos,
subscription-manager\\nThis system is not registered to Red Hat Subscription Management.
You can use subscription-manager to register.\\nResolving Dependencies\\n-->
Running transaction check\\n--->
Package demo-tomcat-1.noarch 0:SNAPSHOT-1 will be installed\\n-->
Finished Dependency Resolution\\n
\\nDependencies
Resolved\\n\\n==================================================================\\n
Package Arch Version Repository
Size\\n========================================================================
=====\\nInstalling:\\n demo-tomcat-1 noarch SNAPSHOT-1 demo-repo1 7.1 M\\n\\nTransaction
Summary\\n=========================================================\\nInstall  1
Package\\n\\nTotal download size: 7.1 M\\nInstalled size: 7.9 M\\nDownloading
packages:\\nRunning
transaction check\\nRunning transaction test\\nTransaction test succeeded\\nRunning
transaction\\n
Installing : demo-tomcat-1-SNAPSHOT-1.noarch 1/1 \\n  Verifying  :
demo-tomcat-1-SNAPSHOT-1.noarch
1/1 \\n\\nInstalled:\\n  demo-tomcat-1.noarch 0:SNAPSHOT-1  \\n\\nComplete!\\n'], u'rc': 0
}",
"Installed Tomcat artifacts - True"
]
}
TASK [install-tomcat : Clean DEMO environment] ****************************************
************************************************************
task path: /users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:19
Tuesday 21 November 2017  13:02:13 +0530 (0:00:00.057) 0:00:08.387 ******
[WARNING]: when statements should not include jinja2 templating delimiters such as {{ }} or
{% %}. Found: {{installationOutput.changed}}
Using module file /usr/lib/python2.7/sitepackages/ansible/modules/files/file.py
<localhost> ESTABLISH LOCAL CONNECTION FOR USER: root
<localhost> EXEC /bin/sh -c 'echo ~ && sleep 0'
<localhost> EXEC /bin/sh -c '( umask 77 && mkdir -p "` echo
/root/.ansible/tmp/ansible-tmp-1511249534.13-128345805983963 `" && echo
ansible-tmp-1511249534.13-128345805983963="` echo
/root/.ansible/tmp/ansibletmp-1511249534.13-128345805983963 `" ) && sleep 0'
<localhost> PUT /tmp/tmp0aXel7 TO
/root/.ansible/tmp/ansible-tmp-1511249534.13128345805983963/file.py
<localhost> EXEC /bin/sh -c 'chmod u+x
/root/.ansible/tmp/ansible-tmp1511249534.13-128345805983963/
/root/.ansible/tmp/ansible-tmp-1511249534.13128345805983963/file.py && sleep 0'
<localhost> EXEC /bin/sh -c '/usr/bin/python
/root/.ansible/tmp/ansible-tmp1511249534.13-128345805983963/file.py; rm -rf
"/root/.ansible/tmp/ansible-tmp1511249534.13-128345805983963/" > /dev/null 2>&1
&& sleep 0'
changed: [server1] => {
"changed": true,
"diff": {
"after": {
"path": "/users/demo/DEMO",
"state": "absent"
},
"before": {
"path": "/users/demo/DEMO",
"state": "directory"
}
},
"invocation": {
"module_args": {
"attributes": null,
"backup": null,
"content": null,
"delimiter": null,
"diff_peek": null,
"directory_mode": null,
"follow": false,
"force": false,
"group": null,
"mode": null,
"original_basename": null,
"owner": null,
"path": "/users/demo/DEMO",
"recurse": false,
"regexp": null,
"remote_src": null,
"selevel": null,
"serole": null,
"setype": null,
"seuser": null,
"src": null,
"state": "absent",
"unsafe_writes": null,
"validate": null
}
},
"path": "/users/demo/DEMO",
"state": "absent"
}
TASK [install-tomcat : debug] ********************************************************
*************************************************************
task path: /users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:29
Tuesday 21 November 2017  13:02:14 +0530 (0:00:00.257)       0:00:08.645 ******
ok: [server1] => {
"changed": false,
"msg": [
"Clean DEMO environment task ended with message:{u'diff': {u'after': {u'path':
u'/users/demo/DEMO', u'state': u'absent'},
u'before': {u'path': u'/users/demo/DEMO', u'state': u'directory'}}, u'state': u'absent',
u'changed': True, u'path': u'/users/demo/DEMO'}",
"check value  :True"
]
}
TASK [install-tomcat : Copy Tomcat to user home] *************************************
********************************************************
task path: /users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:37
Tuesday 21 November 2017  13:02:14 +0530 (0:00:00.055)       0:00:08.701 ******
[WARNING]: when statements should not include jinja2 templating delimiters such as {{ }} or
{% %}. Found: {{installationOutput.changed}}
Using module file /usr/lib/python2.7/sitepackages/ansible/modules/commands/command.py
<localhost> ESTABLISH LOCAL CONNECTION FOR USER: root
<localhost> EXEC /bin/sh -c 'echo ~ && sleep 0'
<localhost> EXEC /bin/sh -c '( umask 77 && mkdir -p "` echo
/root/.ansible/tmp/ansible-tmp-1511249534.43-41077200718443 `" && echo
ansibletmp-1511249534.43-41077200718443="` echo
/root/.ansible/tmp/ansible-tmp1511249534.43-41077200718443 `" ) && sleep 0'
<localhost> PUT /tmp/tmp25deWs TO
/root/.ansible/tmp/ansible-tmp-1511249534.4341077200718443/command.py
<localhost> EXEC /bin/sh -c 'chmod u+x
/root/.ansible/tmp/ansible-tmp1511249534.43-41077200718443/
/root/.ansible/tmp/ansible-tmp-1511249534.4341077200718443/command.py && sleep 0'
<localhost> EXEC /bin/sh -c '/usr/bin/python
/root/.ansible/tmp/ansible-tmp1511249534.43-41077200718443/command.py; rm -rf
"/root/.ansible/tmp/ansibletmp-1511249534.43-41077200718443/" > /dev/null 2>&1
&& sleep 0'
changed: [server1] => {
"changed": true,
"cmd": [
"cp",
"-r",
"/opt/ansible/tomcat/demo",
"/users/demo/DEMO/"
],
"delta": "0:00:00.017923",
"end": "2017-11-21 13:02:14.547633",
"invocation": {
"module_args": {
"_raw_params": "cp -r /opt/ansible/tomcat/demo /users/demo/DEMO/",
"_uses_shell": false,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"warn": true
}
},
"rc": 0,
"start": "2017-11-21 13:02:14.529710",
"stderr": "",
"stderr_lines": [],
"stdout": "",
"stdout_lines": []
}
TASK [install-tomcat : debug] ********************************************************
**********************************************************
task path: /users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:47
Tuesday 21 November 2017  13:02:14 +0530 (0:00:00.260)       0:00:08.961 ******
ok: [server1] => {
"changed": false,
"msg": "Copy Tomcat to user home task ended with message {
'stderr_lines': [], u'changed': True, u'end': u'2017-11-21 13:02:14.547633', u'stdout':
u'', u'cmd': [u'cp', u'-r', u'/opt/ansible/tomcat/demo', u'/users/demo/DEMO/'], u'rc': 0,
u'start': u'2017-11-21 13:02:14.529710', u'stderr': u'', u'delta': u'0:00:00.017923',
'stdout_lines': []}"
}
TASK [start-tomcat : Start Tomcat] **************************************************
**********************************************************
task path: /users/demo/vivek-playbook/roles/start-tomcat/tasks/main.yml:5
Tuesday 21 November 2017  13:02:14 +0530 (0:00:00.044)       0:00:09.006 ******
Using module file /usr/lib/python2.7/sitepackages/ansible/modules/commands/command.py
<localhost> ESTABLISH LOCAL CONNECTION FOR USER: root
<localhost> EXEC /bin/sh -c 'echo ~ && sleep 0'
<localhost> EXEC /bin/sh -c '( umask 77 && mkdir -p "` echo
/root/.ansible/tmp/ansible-tmp-1511249534.63-46501211251197 `" && echo
ansibletmp-1511249534.63-46501211251197="` echo
/root/.ansible/tmp/ansible-tmp1511249534.63-46501211251197 `" ) && sleep 0'
<localhost> PUT /tmp/tmp9f06MQ TO
/root/.ansible/tmp/ansible-tmp-1511249534.6346501211251197/command.py
<localhost> EXEC /bin/sh -c 'chmod u+x
/root/.ansible/tmp/ansible-tmp1511249534.63-46501211251197/
/root/.ansible/tmp/ansible-tmp-1511249534.6346501211251197/command.py && sleep 0'
<localhost> EXEC /bin/sh -c '/usr/bin/python
/root/.ansible/tmp/ansible-tmp1511249534.63-46501211251197/command.py; rm -rf
"/root/.ansible/tmp/ansibletmp-1511249534.63-46501211251197/" > /dev/null 2>&1
&& sleep 0'
changed: [server1] => {
"changed": true,
"cmd": [ "/users/demo/DEMO/bin/startup.sh" ],
"delta": "0:00:00.020024",
"end": "2017-11-21 13:02:14.741649",
"invocation": {
"module_args": {
"_raw_params": "/users/demo/DEMO/bin/startup.sh",
"_uses_shell": false,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"warn": true
}
},
"rc": 0,
"start": "2017-11-21 13:02:14.721625",
"stderr": "",
"stderr_lines": [],
"stdout": "Tomcat started.",
"stdout_lines": [ "Tomcat started." ]
}
TASK [start-tomcat : debug] *************************************************
**********************************************************************
task path: /users/demo/vivek-playbook/roles/start-tomcat/tasks/main.yml:10
Tuesday 21 November 2017  13:02:14 +0530 (0:00:00.150)       0:00:09.156 ******
ok: [server1] => {
"changed": false,
"msg": [
"Start Tomcat task ended with message: {'
stderr_lines': [], u'changed': True, u'end': u'2017-11-21 13:02:14.741649', u'stdout':
u'Tomcat started.', u'cmd': [u'/users/demo/DEMO/bin/startup.sh'], u'rc': 0, u'start':
u'2017-11-21 13:02:14.721625', u'stderr': u'', u'delta': u'0:00:00.020024',
'stdout_lines': [u'Tomcat started.']}",
"Tomcat started - True"
]
}
META: ran handlers
META: ran handlers
PLAY RECAP *******************************************************************************
*********************************************************
server1  : ok = 9    changed = 4    unreachable = 0    failed = 0
Tuesday 21 November 2017  13:02:14 +0530 (0:00:00.042)       0:00:09.198 ******
===============================================================================
install-tomcat : Install Tomcat artifacts ------------------------------- 6.76s
/users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:5 --------------
Gathering Facts --------------------------------------------------------- 1.52s
------------------------------------------------------------------------------
install-tomcat : Copy Tomcat to user home ------------------------------- 0.26s
/users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:37 -------------
install-tomcat : Clean DEMO environment --------------------------------- 0.26s
/users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:19 -------------
start-tomcat : Start Tomcat --------------------------------------------- 0.15s
/users/demo/vivek-playbook/roles/start-tomcat/tasks/main.yml:5 ----------------
install-tomcat : debug -------------------------------------------------- 0.06s
/users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:11 -------------
install-tomcat : debug -------------------------------------------------- 0.06s
/users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:29 -------------
install-tomcat : debug -------------------------------------------------- 0.04s
/users/demo/vivek-playbook/roles/install-tomcat/tasks/main.yml:47 -------------
start-tomcat : debug ---------------------------------------------------- 0.04s
/users/demo/vivek-playbook/roles/start-tomcat/tasks/main.yml:10 ---------------
Hit the following URL and you will be directed to a page as shown below − http://10.76.0.134:11677/HelloWorld/HelloWorld

The deployed war just has a servlet which displays “Hello World”. The detailed output shows the time taken by each and every task because of the entry added in ansible.cfg file −
[defaults]
callback_whitelist = profile_tasks

So, this brings us to the end of blog. This Tecklearn ‘Concept of Roles in Ansible’ blog helps you with commonly asked questions if you are looking out for a job in DevOps. If you wish to learn Ansible and build a career in DevOps domain, then check out our interactive, Configuration Management using Ansible Training, that comes with 24*7 support to guide you throughout your learning period. Please find the link for course details:

https://www.tecklearn.com/course/configuration-management-using-ansible/

Configuration Management using Ansible Training

About the Course

Tecklearn has specially designed this Configuration Management using Ansible Training Course to advance your skills for a successful career in this domain. The course will cover different components of Ansible and how they are used in software development operations. You will get an in-depth knowledge of these concepts and will be able to work on related demos. Upon completion of this online training, you will hold a solid understanding and hands-on experience with Ansible.

Why Should you take Configuration Management using Ansible Training?

The average Ansible salary in USA is $136,500 per year or $70 per hour. Entry level positions start at $100,000 per year while most experienced workers make up to $187,500 per year.
Wells Fargo, Capital One, Apple, CISCO & many other MNC’s worldwide use Ansible across industries.
According to Grand View Research, the DevOps market size is estimated to be worth $12.85 billion by 2025. DevOps professionals are highly paid and in-demand throughout industries including retail, eCommerce, finance, and technology.

What you will Learn in this Course?

Introduction to DevOps

What is Software Development
Software Development Life Cycle
Why DevOps?
What is DevOps?
DevOps Lifecycle
DevOps Tools
Benefits of DevOps
How DevOps is related to Agile Delivery
DevOps Implementation

Configuration Management using Ansible

What is Ansible?
Ansible vs Puppet
Ansible Architecture
Ansible Installation
Setting up Master Slave using Ansible
Configuring Ansible Roles
Write Playbooks
Applying configuration using Ansible
Hands on

Got a question for us? Please mention it in the comments section and we will get back to you.

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