AWS API Deployment - amazon-web-services

Question

I have created a cloudformation template to create api gateway/resource/method/function on AWS platform, and also associated a lambda function to my api. Once I create the stack I get a url to hit my aws api. Whenever I hit this url, I get internal server error.
I am not sure what could be the reason, but if I toggle between 2 lambda functions from aws console for integration request and deploy, it starts working as expected.
I don't want to do it manually as deployment should be done at the time of stack creation.
Below is the template I used to create resources
Resources:
RestApi:
Type: AWS::ApiGateway::RestApi
Properties:
Name: !Sub 'testing'
EndpointConfiguration:
Types:
- 'EDGE'
ApigwResource:
Type: AWS::ApiGateway::Resource
Properties:
RestApiId: !Ref RestApi
ParentId: !GetAtt RestApi.RootResourceId
# lambda function
LambdaFunction:
Type: AWS::Lambda::Function
Properties:
Role: 'lambda_role'
Handler: lambda_s3.lambda_handler
Code:
S3Bucket: { 'Fn::ImportValue': !Sub '${S3Bucket}-S3AppsBucketId' }
S3Key: 'lambda_source_code'
Runtime: python3.7
MemorySize: 128
Timeout: 60
FunctionName: !Sub 'lambda_function'
ApiGatewayMethod:
Type: AWS::ApiGateway::Method
Properties:
HttpMethod: PUT
ResourceId: !Ref ApigwResource
RestApiId: !Ref RestApi
AuthorizationType: AWS_IAM
MethodResponses:
- ResponseModels: { 'application/json' : 'Empty' }
StatusCode: 200
Integration:
Type: AWS
IntegrationHttpMethod: PUT
IntegrationResponses:
- StatusCode: 200
Uri: !Sub
- 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${lambdaArn}/invocations'
- lambdaArn: !GetAtt LambdaFunction.Arn
ApiGatewayDeployment:
Type: AWS::ApiGateway::Deployment
DependsOn:
- 'ApiGatewayMethod'
Properties:
RestApiId: !Ref RestApi
StageName: !Ref Environment

Answer 1

I found the problem, my api gateway didn't have permission to invoke lambda function. When I was toggling lambda functions manually, it used to provide necessary permissions to my api gateway thus this work around was working. I added below piece to my cloudformation template to make this work.
ConfigLambdaPermission:
Type: "AWS::Lambda::Permission"
DependsOn:
- RestApi
- LambdaFunction
Properties:
Action: lambda:InvokeFunction
FunctionName: !Ref LambdaFunction
Principal: apigateway.amazonaws.com