Ansible for AWS: Introduction to Spot Instance Automation

What are Spot Instance and Spot Instance Requests?

A Spot Instance is an instance that uses spare AWS EC2 capacity that is available for less than the On-Demand price. Because Spot Instances provide the ability to request unused EC2 instances at steep discounts, it can lower your Amazon EC2 costs significantly. 

Spot Instances are a cost-effective choice if you can be flexible about when your applications run and whether your applications can be interrupted. For example, Spot Instances are well-suited for data analysis, batch jobs, background processing, and optional tasks.

Managing Spot Instances with Ansible

So you want to manage your Spot Instance Requests with Ansible Automation Platform? When it comes to managing AWS resources, the Ansible Amazon AWS Collection includes a variety of Ansible content to help automate the management of AWS instances. Using Ansible to automate applications in AWS greatly increases the chances that your cloud initiative will be a success.  

With the latest addition of new modules to the Ansible Amazon AWS Collection, we have introduced two new modules to help manage Spot Instance Requests efficiently.

The ec2_spot_instance module helps in creating as well as terminating the Spot Instance Requests, while it’s companion module, ec2_spot_instance_info helps in gathering details about the Spot Instance Requests.

Let’s Deep Dive:

EC2 Spot Instance Module

The EC2 Spot Instance module helps create and terminate spot instance requests easily with Ansible Playbooks. With help of this module, we can create a simple Spot Instance Request with minimal options, create a Spot Instance Request by providing a complex set of options and remove or terminate the Spot Instance Requests that we no longer need.

To use this module in playbooks, use the amazon.aws.ec2_spot_instance key and provide the options as required for creating the Spot Instance Request.

Consider the following example for creating a simple Spot Instance Request.

The task below creates a simple Spot Instance Request with the provided launch specifications:

- name: Simple Spot Instance Request Creation
  amazon.aws.ec2_spot_instance:
    launch_specification:
        image_id: ami-123456789
        key_name: my-keypair
        instance_type: t2.medium

With this new module, we can provide various options while creating Spot Instance Requests. Some of them are mentioned below (to check the complete options, check out the Spot Instance requests documentation from AWS).

• block_device_mappings: A list of hash/dictionaries of volumes to add to the new instance.
• network_interfaces: One or more network interfaces. If you specify a network interface, you must specify subnet IDs and security group IDs using the network interface.
• placement: The placement information for the instance.
• monitoring: Indicates whether basic or detailed monitoring is enabled for the instance.
• spot_price: Maximum spot price to bid. If not set, a regular on-demand instance is requested.
• tags: A dictionary of key-value pairs for tagging the Spot Instance request on creation.

Example task for creating a Spot Instance Request with the more options:

- name: Spot Instance Request Creation with more options
  amazon.aws.ec2_spot_instance:
    launch_specification:
      image_id: ami-123456789
      key_name: my-keypair
      instance_type: t2.medium
      subnet_id: subnet-12345678
    block_device_mappings:
      - device_name: /dev/sdc
        ebs:
          delete_on_termination: True
          volume_type: io2
          volume_size: 30
      - device_name: /dev/sdc
        ebs:
          volume_type: io2
          volume_size: 30
    network_interfaces:
      - associate_public_ip_address: False
        delete_on_termination: True
        device_index: 0
    placement:
      availability_zone: us-west-2a
    monitoring:
      enabled: False
    spot_price: 0.002
    tags:
      Environment: Testing

But what do we do when we no longer need a Spot Instance Request? How do we terminate it?

An example of terminating the Spot Instance Request:

- name: Spot Instance Request Termination
  amazon.aws.ec2_spot_instance:
    spot_instance_request_ids: ['sir-12345678', 'sir-abcdefgh']
    state: absent

EC2 Spot Instance Info Module

To review with the EC2 Spot Instance module, we can now create and terminate Spot Instance Requests. But wait a minute, we have created a few Spot Instance Requests and we would like to check on them and know more details

No problem! With the new EC2 Spot Instance Info module, we have it covered for all needs with the Spot Instance Requests. We can use the new EC2 Spot Instance Info module to get details of our Spot Instance Requests.

An example to gather details of particular Spot Instance Request(s) based on IDs:

- name: describe the Spot Instance requests based on request IDs
    amazon.aws.ec2_spot_instance_info:
      spot_instance_request_ids:
  	  - sir-12345678
	  - sir-87654321

What if we have so many Spot Instance Requests that we want to filter based on an image ID, state of the request or instance type? You can use one or more filters supported by the module to filter the results as per your requirements.

Some of the filters supported are:

• launch.image-id: The ID of the AMI.
• state: The state of the Spot Instance request (open | active | closed | cancelled | failed). Spot request status information can help you track your Amazon EC2 Spot Instance requests.
• launch.instance-type: The type of instance (for example, m3.medium). 

Check out Describe Spot Instance Requests for more filters.

An example to gather details of Spot Instance Requests and filter the results:

- name: describe the Spot Instance requests based on request IDs
  amazon.aws.ec2_spot_instance_info:
    spot_instance_request_ids:
      - sir-12345678
	- sir-87654321

Example:

The playbooks below create two Spot Instance Requests, get the details about the requests, and filter the result and terminate the Spot Instance Requests.

To create Spot Instance Requests:

---
- name: test the spot_instance module creation
 hosts: localhost
 tasks:
   - name: Create a Spot Instance Request
 	amazon.aws.ec2_spot_instance:
   	  launch_specification:
     	    image_id: ami-1234567890
     	    key_name: my-key
     	    instance_type: t3.micro
          subnet_id: subnet-1234567890
 
   - name: Create another Spot Instance Request
 	amazon.aws.ec2_spot_instance:
   	  launch_specification:
     	    image_id: ami-1234567890
     	    key_name: my-key
     	    instance_type: c5.large
          subnet_id: subnet-1234567890

To get Spot Instance Request and filter results:

---
- name: test the spot_instance module creation
 hosts: localhost
 tasks:
   - name: Create a Spot Instance Request
     amazon.aws.ec2_spot_instance:
   	  launch_specification:
          image_id: ami-1234567890
          key_name: my-key
          instance_type: t3.micro
     	    subnet_id: subnet-1234567890
 
   - name: Create another Spot Instance Request
     amazon.aws.ec2_spot_instance:
   	  launch_specification:
     	    image_id: ami-1234567890
          key_name: my-key
          instance_type: c5.large
          subnet_id: subnet-1234567890

To terminate the Spot Instance Requests:

---
- name: test the new spot_instance_info module
 hosts: localhost
 tasks:
   - name: Get details about spot instance requests
 	amazon.aws.ec2_spot_instance_info:
   	spot_instance_request_ids:
     	- sir-87654321
     	- sir-12345678
   	filters:
     	launch.instance-type: t3.micro

Moving forward

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