YAML version of tmaslen's API Gateway cloudformation template - useful when you don't want to use SAM

example-api-gateway.yaml

---
AWSTemplateFormatVersion: '2010-09-09'
Description: Sample template that contains a Lambda function behind an API GW
Resources:
  # BEGIN: Should only need this in an empty API Gateway situation
  ApiGatewayCloudWatchLogsRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - apigateway.amazonaws.com
            Action:
              - sts:AssumeRole
      Policies:
        - PolicyName: ApiGatewayLogsPolicy
          PolicyDocument:
            Version: '2012-10-17'
            Statement:
              - Effect: Allow
                Action:
                  - logs:CreateLogGroup
                  - logs:CreateLogStream
                  - logs:DescribeLogGroups
                  - logs:DescribeLogStreams
                  - logs:PutLogEvents
                  - logs:GetLogEvents
                  - logs:FilterLogEvents
                Resource: "*"
  ApiGatewayAccount:
    Type: AWS::ApiGateway::Account
    Properties:
      CloudWatchRoleArn: !GetAtt ApiGatewayCloudWatchLogsRole.Arn
  # END: Should only need this in an empty API Gateway situation
  GreetingLambda:
    Type: AWS::Lambda::Function
    Properties:
      Code:
        ZipFile: |
          'use strict';

          // Greeter Lambda
          exports.handler = (event, context, callback) => {
            console.log('Event:', JSON.stringify(event));
            const name = event.params.querystring.name || event.body.name || 'World';
            const response = {greeting: `Hello, ${name}!`};
            callback(null, response);
          };
      Description: A greeting function
      Handler: index.handler
      Role: !GetAtt LambdaExecutionRole.Arn
      Runtime: nodejs10.x
  LambdaExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: '2012-10-17'
        Statement:
          - Effect: Allow
            Principal:
              Service:
                - lambda.amazonaws.com
            Action:
              - sts:AssumeRole
      ManagedPolicyArns:
        - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
  GreetingApi:
    Type: AWS::ApiGateway::RestApi
    Properties:
      Description: API used for Greeting requests
      FailOnWarnings: true
      Name: !Ref AWS::StackName
      EndpointConfiguration:
        Types:
          - REGIONAL
  LambdaPermission:
    Type: AWS::Lambda::Permission
    Properties:
      Action: lambda:invokeFunction
      FunctionName: !GetAtt GreetingLambda.Arn
      Principal: apigateway.amazonaws.com
      SourceArn: !Sub 'arn:${AWS::Partition}:execute-api:${AWS::Region}:${AWS::AccountId}:${GreetingApi}/*'
  GreetingApiStage:
    DependsOn:
      - ApiGatewayAccount
    Type: AWS::ApiGateway::Stage
    Properties:
      DeploymentId: !Ref Deployment
      MethodSettings:
        - DataTraceEnabled: true
          HttpMethod: "*"
          LoggingLevel: INFO
          ResourcePath: "/*"
      RestApiId: !Ref GreetingApi
      StageName: LATEST
  Deployment:
    Type: AWS::ApiGateway::Deployment
    DependsOn:
      - GreetingRequestGET
      - GreetingRequestPOST
    Properties:
      RestApiId: !Ref GreetingApi
      StageName: Production
  GreetingResource:
    Type: AWS::ApiGateway::Resource
    Properties:
      RestApiId: !Ref GreetingApi
      ParentId: !GetAtt GreetingApi.RootResourceId
      PathPart: greeting
  GreetingRequestGET:
    DependsOn: LambdaPermission
    Type: AWS::ApiGateway::Method
    Properties:
      AuthorizationType: NONE
      HttpMethod: GET
      Integration:
        Type: AWS
        IntegrationHttpMethod: POST
        Uri: !Sub 'arn:${AWS::Partition}:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GreetingLambda.Arn}/invocations'
        IntegrationResponses:
          - StatusCode: 200
        RequestTemplates:
          application/json: |
            ##  See http://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-mapping-template-reference.html
            ##  This template will pass through all parameters including path, querystring, header, stage variables, and context through to the integration endpoint via the body/payload
            #set($allParams = $input.params())
            {
            "body" : $input.json('$'),
            "params" : {
            #foreach($type in $allParams.keySet())
                #set($params = $allParams.get($type))
            "$type" : {
                #foreach($paramName in $params.keySet())
                "$paramName" : "$util.escapeJavaScript($params.get($paramName))"
                    #if($foreach.hasNext),#end
                #end
            }
                #if($foreach.hasNext),#end
            #end
            },
            "stageVariables" : {
            #foreach($key in $stageVariables.keySet())
            "$key" : "$util.escapeJavaScript($stageVariables.get($key))"
                #if($foreach.hasNext),#end
            #end
            },
            "context" : {
                "accountId" : "$context.identity.accountId",
                "apiId" : "$context.apiId",
                "apiKey" : "$context.identity.apiKey",
                "authorizerPrincipalId" : "$context.authorizer.principalId",
                "caller" : "$context.identity.caller",
                "cognitoAuthenticationProvider" : "$context.identity.cognitoAuthenticationProvider",
                "cognitoAuthenticationType" : "$context.identity.cognitoAuthenticationType",
                "cognitoIdentityId" : "$context.identity.cognitoIdentityId",
                "cognitoIdentityPoolId" : "$context.identity.cognitoIdentityPoolId",
                "httpMethod" : "$context.httpMethod",
                "stage" : "$context.stage",
                "sourceIp" : "$context.identity.sourceIp",
                "user" : "$context.identity.user",
                "userAgent" : "$context.identity.userAgent",
                "userArn" : "$context.identity.userArn",
                "requestId" : "$context.requestId",
                "resourceId" : "$context.resourceId",
                "resourcePath" : "$context.resourcePath"
                }
            }
      RequestParameters:
        method.request.querystring.name: false
      ResourceId: !Ref GreetingResource
      RestApiId: !Ref GreetingApi
      MethodResponses:
        - StatusCode: 200
  GreetingRequestPOST:
    DependsOn: LambdaPermission
    Type: AWS::ApiGateway::Method
    Properties:
      AuthorizationType: NONE
      HttpMethod: POST
      Integration:
        Type: AWS
        IntegrationHttpMethod: POST
        Uri: !Sub 'arn:${AWS::Partition}:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GreetingLambda.Arn}/invocations'
        IntegrationResponses:
          - StatusCode: 200
        RequestTemplates:
          application/json: |
            ##  See http://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-mapping-template-reference.html
            ##  This template will pass through all parameters including path, querystring, header, stage variables, and context through to the integration endpoint via the body/payload
            #set($allParams = $input.params())
            {
            "body" : $input.json('$'),
            "params" : {
            #foreach($type in $allParams.keySet())
                #set($params = $allParams.get($type))
            "$type" : {
                #foreach($paramName in $params.keySet())
                "$paramName" : "$util.escapeJavaScript($params.get($paramName))"
                    #if($foreach.hasNext),#end
                #end
            }
                #if($foreach.hasNext),#end
            #end
            },
            "stageVariables" : {
            #foreach($key in $stageVariables.keySet())
            "$key" : "$util.escapeJavaScript($stageVariables.get($key))"
                #if($foreach.hasNext),#end
            #end
            },
            "context" : {
                "accountId" : "$context.identity.accountId",
                "apiId" : "$context.apiId",
                "apiKey" : "$context.identity.apiKey",
                "authorizerPrincipalId" : "$context.authorizer.principalId",
                "caller" : "$context.identity.caller",
                "cognitoAuthenticationProvider" : "$context.identity.cognitoAuthenticationProvider",
                "cognitoAuthenticationType" : "$context.identity.cognitoAuthenticationType",
                "cognitoIdentityId" : "$context.identity.cognitoIdentityId",
                "cognitoIdentityPoolId" : "$context.identity.cognitoIdentityPoolId",
                "httpMethod" : "$context.httpMethod",
                "stage" : "$context.stage",
                "sourceIp" : "$context.identity.sourceIp",
                "user" : "$context.identity.user",
                "userAgent" : "$context.identity.userAgent",
                "userArn" : "$context.identity.userArn",
                "requestId" : "$context.requestId",
                "resourceId" : "$context.resourceId",
                "resourcePath" : "$context.resourcePath"
                }
            }
      RequestParameters:
        method.request.querystring.name: false
      ResourceId: !Ref GreetingResource
      RestApiId: !Ref GreetingApi
      MethodResponses:
        - StatusCode: 200
Outputs:
  RootUrl:
    Description: Root URL of the API gateway
    Value: !Sub 'https://${GreetingApi}.execute-api.${AWS::Region}.amazonaws.com'