Introduction

In today's IT landscape, the automation of cloud infrastructure has become a pivotal aspect of managing scalable, reliable, and efficient systems. Oracle Cloud Infrastructure (OCI) is one such platform that benefits greatly from automation. This article will guide you through creating a compute instance pool and launching instances in OCI using Ansible, providing a detailed example and best practices.

Understanding Ansible

Ansible is an open-source automation tool that simplifies the management of complex IT environments. It uses a human-readable language, YAML, to describe automation jobs, known as playbooks. Ansible is agentless, using SSH or WinRM for communication, making it a secure and efficient choice for IT automation.

Key Features of Ansible

1. Human-Readable Automation: Uses YAML for playbooks, making it easy to read and write.

2. Agentless Architecture: Requires no agents on the managed nodes, reducing overhead and security risks.

3. Cross-Platform Support: Works with Linux, Windows, UNIX, and network devices.

4. Extensible: Can be extended with modules and plugins written in any language.

Setting Up the Environment

Before diving into the playbook, ensure you have the following prerequisites:

1. Ansible Installed: Ensure Ansible is installed on your control node. You can install it using pip:

``bash

pip install ansible

`

2. OCI CLI Configured: Configure the OCI CLI on your control node. Follow the [OCI CLI installation guide](https://docs.oracle.com/en-us/iaas/Content/API/SDKDocs/cliinstall.htm).

Sample Playbook: Creating a Compute Instance Pool

Below is a sample Ansible playbook to create a compute instance pool in OCI and launch instances.

``yaml

---

Copyright (c) 2020, 2024 Oracle and/or its affiliates.

This software is made available to you under the terms of the GPL 3.0 license or the Apache 2.0 license.

GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)

Apache License v2.0

See LICENSE.TXT for details.

  • name: Create a compute instance pool and launch instances

hosts: localhost

collections:

- oracle.oci

vars:

# Common networking definitions

quad_zero_route: "0.0.0.0/0"

TCP_protocol: "6"

SSH_port: "22"

vcn_name: "ansible-sample-create-instance-pool-vcn"

vcn_cidr_block: "10.0.0.0/16"

vcn_dns_label: "samplevcn"

ig_name: "ansible-sample-create-instance-pool-ig"

route_table_name: "ansible-sample-create-instance-pool-rt"

# Route all internet access to our Internet Gateway

route_table_rules:

- cidr_block: "{{ quad_zero_route }}"

network_entity_id: "{{ ig_id }}"

subnet_cidr: "10.0.0.48/28"

subnet_name: "ansible-sample-create-instance-pool-subnet"

subnet_dns_label: "samplesubnet"

securitylist_name: "ansible-sample-create-instance-pool-sec-list"

instance_shape: "{{ lookup('env', 'SAMPLE_INSTANCE_SHAPE') | default('VM.Sta