Ansible Service Module

Introduction to Ansible Service Module

Ansible has many built-in modules in it and many custom modules you can create based on your needs. Importance of modules depends upon the work they do and the node on which you are going to push the change. For Unix/Linux remote hosts, one such important module is a service module, which supports init systems like systemd, sysV, BSD init, OpenRC, etc. In this article, we will try to understand ansible service module, its various options and ways of working.

What is Ansible Service Module?

As service module is for Unix/Linux machines, similarly, for windows, there is a similar module named win_service module. Also, if the remote hosts use systemd to manage services on it, then there is another module named system which can be used to manage services on remote hosts from Ansible control node. Like any other module, Ansible service module comes with some parameters and these parameters have their own options or acceptable values. Using these parameters with required values, we can manage services by doing operations like stop, start, reload etc. on remote hosts. We will see these operations in coming sections of this article.

Parameters & Options of Ansible Service Module

In Ansible, below are the available parameters which can be used to manage service on remote hosts: –

1. Enable: To set whether service should start on boot up. Below are acceptable

• yes: if it should.
• no: if it shouldn’t.

2. Name: The name of service. It accepts strings as service.

3. Sleep: If restart is used, then this value will be the waiting period between stop and start of service. But system doesn’t support it. It accepts integer values as seconds to wait as sleep.

4. State: To define the required state of service and operation with service if this is not in desired state. This accepts below values: –

• started: To start a service if not.
• stopped: To stop a service if not.
• restarted: To restart a service by bouncing.
• reloaded: To reload a service means to start if not already.

5. Use: If there is a preference for service manager on remote hosts, the this can be Otherwise, by default, service modules use ansible_service_mgr fact for auto-detecting the service manager on remote hosts.

6. Pattern: If status command doesn’t respond for the service name given. Then you can use a substring as pattern to check against the output of ps command which then checks the matching process on remote hosts for this pattern value. If match is found, then service is assumed to be

Examples of Ansible Service Module

Before we start, let’s first understand the environment, we use here. We have two nodes named host- one and host-two which are managed by Ansible Control server ansible-controller.

1. Start a Service

To start a service using ansible command, but the output will be in JSON format and more

ansible all -m service -a "name=httpd state=started"

Similarly, for doing the same task by using ansible-playbook you need to create a file like below:

Code:

- hosts: all tasks:
- name: starting a service service:
name: httpd state: started

Then use the below command to run it, which will start httpd service on target nodes.

ansible-playbook start_service.yaml

Output:

2. Stop a Service

To stop a service using ansible command:

ansible all -m service -a "name=crond state=stopped"

Similarly, for doing the same task by using ansible-playbook you need to create a file like below:

Code:

- hosts: all tasks:
- name: stopping a service service:
name: httpd state: stopped

Then use the below command to run it, which will start httpd service on target nodes.

ansible-playbook stop_service.yaml

Output:

3. Restart Service

To restart a service using ansible command:

ansible all -m service -a "name=httpd state=restarted"

Similarly, for doing the same task by using ansible-playbook you need to create a file like below:

Code:

- hosts: all tasks:
- name: restarting a service service:
name: httpd state: restarted

Then use the below command to run it, which will start httpd service on target nodes.

ansible-playbook restart_service.yaml

Output:

4. Start and Enable Service

To start and enable a service using ansible command, so that service will automatically start on server:

ansible all -m service -a "name=httpd state=started enabled=yes"

Similarly, for doing the same task by using ansible-playbook you need to create a file like below:

Code:

- hosts: all tasks:
- name: starting and enabling a service service:
name: httpd state: started enabled: yes

Then use the below command to run it, which will start httpd service on target nodes.

ansible-playbook start_enable_service.yaml

Output:

5. Working on Multiple Services in Single Playbook

For doing this task by using ansible-playbook you need to create a file like below:

Code:

-hosts: all tasks:
-name: reload multiple services service:
name: "{{ item }}" state: reloaded with_items:
-crond
-httpd

Then use the below command to run it, which will start httpd service on target nodes.

ansible-playbook reload_multiple_service.yaml

Output:

6. Working Differently on Different Servers

For doing this task by using ansible- playbook you need to create a file like below:

Code:

hosts: host-one tasks:
name: start httpd on host-one service:
name: httpd state: started
hosts: host-two tasks:
name: stop httpd on host-two service:
name: httpd state: stopped

Then use the below command to run it, which will start httpd service on target nodes.

ansible-playbook diff_service_diff_server.yaml

Output:

7. Capturing the Output & Display

For doing this task by using ansible-playbook you need to create a file like below:

Code:

hosts: host-one tasks:
- name: start service crond service:
name: crond state: started enabled: true
register: service_output
debug: var=service_output.state

Then use the below command to run it, which will start httpd service on target nodes.

ansible-playbook service_operation_status.yaml

Output:

Conclusion

Ansible service module is one of those modules which you need very frequently while doing automation of configuration management of your infrastructure remotely. Though it doesn’t have too many options and parameters, but as this is one of the basic modules, your hands-on experience on it, is needed in the production environment.

Recommended Article

This is a guide to Ansible Service Module. Here we discuss What is Ansible Service Module and its different parameters along with examples as well as Code Implementation. You can also go through our other suggested articles to learn more –

1. Ansible Commands
2. Ansible Architecture
3. Ansible Filters
4. Ansible Debug