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Customizing CloudFormation Resources

UFO allows you to customize the CloudFormation template with the ECS resources by merging in your own custom YAML.

The properties in the file .ufo/config/cfn/dev.yml map directly to ufo’s CloudFormation resources. Here’s a list of the resources that you can customize:

  • Dns
  • EcsSecurityGroup
  • EcsSecurityGroupRule
  • EcsService
  • Elb
  • ElbSecurityGroup
  • ExecutionRole
  • Listener
  • ListenerSsl
  • ScalingPolicy
  • ScalingRole
  • ScalingTarget
  • TargetGroup
  • TaskDefinition
  • TaskRole

Refer to the source code for the latest list: stack/builder/resources.rb

Customization Example

Let’s customize the AWS::ElasticLoadBalancingV2::TargetGroup resource created by CloudFormation. We’ll adjust the deregistration_delay.timeout_seconds to 8. Here’s the relevant section

.ufo/config/cfn/base.yml

TargetGroup:
...
  TargetGroupAttributes:
  - Key: deregistration_delay.timeout_seconds
    Value: 8

The value will be merged to the generated CloudFormation template under the corresponding “TargetGroup Properties”. The generated template looks something like this:

TargetGroup:
  Properties:
...
    TargetGroupAttributes:
    - Key: deregistration_delay.timeout_seconds
      Value: 8
...

In this way, you can customize and override any properties associated with resources created by the ufo CloudFormation stack.

Layering Support

The base.yml file always get evaluated, and env-specific YAML file is layered or merged together. This minimizes duplication. For example, these files are merged for UFO_ENV=dev.

.ufo/config/cfn/base.yml
.ufo/config/cfn/dev.yml

Note this feature is available in v6+.