Creating a load-balanced web service on cloud with Ansible

With the following playbook, we create the load balancer, indicating the name of our backend instances:

$ cat gce-lb.yml

---
- name: Playbook to create gce load balancing instance
  hosts: localhost
  connection: local
  gather_facts: True

  vars:
     service_account_email: <Your gce service account email>
     credentials_file: <Your json credentials file>
     project_id: <Your project id>

 tasks:
    - name: Create gce load balancer
    gce_lb:
      name: lbserver
      state: present
      region: us-central1
      members: ['us-central1-a/web1','us-central1-a/web2','us-central1-a/web3']
      httphealthcheck_name: hc
      httphealthcheck_port: 80
      httphealthcheck_path: "/"
      service_account_email: "{{ service_account_email }}"
      credentials_file: "{{ credentials_file }}"
      project_id: "{{ project_id }}"
$

We use the following playbook to join both tasks and obtain the simple instances of GCE Red Hat Enterprise Linux / Apache with load balancing:

$ cat gce-lb-apache.yml

---
# Playbook to create simple instances of gce centos/apache with load balancing
- import_playbook: gce-apache.yml
- import_playbook: gce-lb.yml
$

Run the playbook:

$ ansible-playbook gce-lb-apache.yml --key-file <Your_id_rsa_key>

When finished, we can check by curl, that the load balancer ip responds with the page published by each instance:

$ curl http://<your.load.balancer.ip>

Check out the video of the playbook run:

Summary and Closing

What we’ve done here is to create (or re-use) playbooks to manage a task that would normally take an admin an hour or more if done manually. The initial learning curve around Ansible playbooks will pay off quickly when you start to use it for repetitive tasks that it can accomplish in minutes versus the time it takes you to do it manually. It also provides a form of documentation for new hires and more junior admins who can see how it’s done by reading off Ansible playbooks.

Finally, automation is key for shops that are looking to embrace DevOps best practices. I hope this example encourages you to use Ansible today to tackle a task you can automate!

Alex Callejas is a Technical Account Manager (TAM) based in Mexico City with more than 10 years experience as a system administrator.