OpenShift AWS IPI Installation with Existing AWS Resources

Resources to make an IPI installation easier when using existing AWS resources

Existing VPC

First create the VPC and subnets, the CloudFormation template came from our docs

aws cloudformation deploy --template-file existing-vpc/vpc.yaml --stack-name my-existing-vpc

This will create the VPC and create subnets in three Availabilty Zones, the output will contain the subnet IDs that will plug into the install-config.yaml

install-config.yaml

...
platform:
  aws:
    region: us-east-2
    subnets:
    - subnet-public-AZ-1
    - subnet-private-AZ-2
    - subnet-public-AZ-3
    - subnet-private-AZ-4
    - subnet-public-AZ-5
    - subnet-private-AZ-6
...

If you set the CloudFormation template parameter --parameter-overrides AvailabilityZoneCount 1 then it will only create subnets in the first Availabilty Zone and further changes will be required for the install-config.yaml.

...
controlPlane:
  platform:
    aws:
      zones:
      - us-east-2a
...
compute:
- platform:
    aws:
      zones:
      - us-east-2a
...