InstanceTypAZCheck

This is a CloudFormation Macro that will get information about whether an instance type is available in the AZs where the instance could be built. Needed this because the InstanceType parameter was failing for some regions for the t4g.small instance type in us-east-1 region.

Properties

Property Name	Description
InstanceType	The Instance Type we want to check for availability in all the subnets
Subnets	The subnets we want to check against (will be all in the VPC generally) passed as an array

Return Values

Name	Description
AvailableInAZs	The zones that have the instance type (array)
AvailableInASubnetIds	The SubnetIds that have the instance type (comma separated)

CloudFormation snippet

  # Custom resource to get subset of zones that have the instance type available
  InstanceTypAZCheck:
    Type: Custom::CheckInstanceTypeAvailability
    Properties:
      ServiceToken: arn:aws:lambda:${AWS::Region}:${AWS::AccountId}:function:InstanceTypAZCheck
      InstanceType: !Ref InstanceType
      Subnets:
        Fn::Split:
          - ","
          - Fn::ImportValue: !Sub '${VPCDataStackName}-SubnetIds' 

InstanceTypAZCheck.go

This is the Lambda code for the Macro. It gets the VPC ID and returns the subnet IDs and count of subnets in the VPC.

create.sh

This script creates the role with the permissions that the Lambda needs and deploys the Lambda initially. Probably could combine this with the update.sh to make things easier.

To run this script, you must have a valid session, and the region must be set. In most cases this simply means you set these variables:

• AWS_PROFILE the name of a profile in your ~/.aws/config or ~/.aws/credentials file, e.g. - wf-bia-dev
• AWS_REGION the region you are going to deploy in (normally this will be us-west-2)

The steps of this script are as follows:

1. creates a role with the trust-policy.json and then attaches policies that the Lambda will need.
2. builds the InstanceTypAZCheck.go
3. Deploys the Lambda to the proper account.

update.sh

This script updates the Lambda code (particularly useful during development) same variables apply as for create.sh

The steps of this script are as follows:

1. builds the InstanceTypAZCheck.go
2. Deploys the Lambda to the proper account.

trust-policy.json

The Trust policy for Lambda to use the role that is created in create.sh