AWS SAM - How to override generated resources - amazon-web-services

Question

I'm trying to build a REST API with SAM. My YAML file looks like this:
AWSTemplateFormatVersion: "2010-09-09"
Description: >-
example-rest-api
Transform:
- AWS::Serverless-2016-10-31
Resources:
allEquipmentsFunction:
Type: AWS::Serverless::Function
Properties:
Handler: src/handlers/myModel.getAll
Runtime: nodejs18.x
Architectures:
- x86_64
MemorySize: 128
Timeout: 100
Description: example description
Events:
ApiEvent:
Type: Api
Properties:
Path: /
Method: GET
saveEquipmentFunction:
Type: AWS::Serverless::Function
Properties:
Handler: src/handlers/myModel.save
Runtime: nodejs18.x
Architectures:
- x86_64
MemorySize: 128
Timeout: 100
Description: example description
Events:
Api:
Type: Api
Properties:
Path: /
Method: POST
ApplicationResourceGroup:
Type: AWS::ResourceGroups::Group
Properties:
Name:
Fn::Join:
- ''
- - ApplicationInsights-SAM-
- Ref: AWS::StackName
ResourceQuery:
Type: CLOUDFORMATION_STACK_1_0
ApplicationInsightsMonitoring:
Type: AWS::ApplicationInsights::Application
Properties:
ResourceGroupName:
Fn::Join:
- ''
- - ApplicationInsights-SAM-
- Ref: AWS::StackName
AutoConfigurationEnabled: 'true'
DependsOn: ApplicationResourceGroup
Outputs:
WebEndpoint:
Description: API Gateway endpoint URL for Prod stage
Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/{Stage}"
As I understand it, SAM creates some resources for me in the background. For example:
"ServerlessRestApi": {
"Type": "AWS::ApiGateway::RestApi"
...
How can I override these generated resources? I want to add API Gateway validation model. For this I need to override background generated resources. AWS Resources is not clean enough. What approach should I take if I can't override?

Answer 1

You cannot "override" properties per se, but you can directly create resources if you need greater control.
When you specify an Event: ApiEvent on your function, SAM creates a AWS::ApiGateway::RestApi resource for you. As the docs say, you can reference the RestApi its Logical ID ServerlessRestApi. This is helpful for passing the RestApi to another resource, but not configuring the RestApi itself.
If you need greater control over the Api properties, you should instead explicily create a AWS::Serverless::Api resource. Configure it as required. Then pass the Api reference to your functions event source configuration as the RestApiId.
SAM is a superset of CloudFormation. You can also include AWS::ApiGateway:: resources directly in your SAM template if SAM's abstractions don't fit your use case. This gives you the greatest level of control.