How to keep the same API Gateway URL for all CloudFormation nested stacks?

0
votes

I am developing a REST API using AWS Lambda, API Gateway and CloudFormation. I hit the Cloudformation 500 resources limit, so I had to go for nested stacks. Below is what I tried.

template.yaml

    AWSTemplateFormatVersion: '2010-09-09'
    Transform: AWS::Serverless-2016-10-31
    Description: >
      aws-restapi
    
      Sample SAM Template for aws-restapi
      
    # More info about Globals: https://github.com/awslabs/serverless-application-model/blob/master/docs/globals.rst
    Globals:
      Function:
        Timeout: 5
        VpcConfig:
            SecurityGroupIds:
              - sg-041f2459dcd921e8e
            SubnetIds:
              - subnet-0381db2d
              - subnet-c4d5c4cb
              - subnet-af5c03c8
              - subnet-7487df28
              - subnet-d139d69c
              - subnet-e9e88bd7
    
    Resources:
      GetAllAccountingTypesFunction:
        Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
        Properties:
          CodeUri: aws-restapi/
          Handler: source/accounting-types/accountingtypes-getall.getallaccountingtypes
          Runtime: nodejs14.x
          Events:
            GetAllAccountingTypesAPIEvent:
              Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
              Properties:
                Path: /accountingtypes/getall
                Method: get
      GetAccountingTypeByIDFunction:
        Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
        Properties:
          CodeUri: aws-restapi/
          Handler: source/accounting-types/accountingtypes-byid.getbyid
          Runtime: nodejs14.x
          Events:
            GetAllAccountingTypesAPIEvent:
              Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
              Properties:
                Path: /accountingtypes/getbyid
                Method: get
       # DependsOn: GetAllAccountingTypesFunction
    
      NestedStack:
        Type: AWS::CloudFormation::Stack
        Properties:
          TemplateURL: template_user.yaml

NestedStackTwo:
    Type: AWS::CloudFormation::Stack
    Properties:
      TemplateURL: template_two.yaml
      
    
      LambdaRole:
        Type: 'AWS::IAM::Role'
        Properties:
          AssumeRolePolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Principal:
                  Service:
                    - lambda.amazonaws.com
                Action:
                  - 'sts:AssumeRole'
          Path: /
          ManagedPolicyArns:
            - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
          Policies:
            - PolicyName: root
              PolicyDocument:
                Version: "2012-10-17"
                Statement:
                  - Effect: Allow
                    Action:
                      - ec2:DescribeNetworkInterfaces
                      - ec2:CreateNetworkInterface
                      - ec2:DeleteNetworkInterface
                      - ec2:DescribeInstances
                      - ec2:AttachNetworkInterface
                    Resource: '*'
    
    Outputs:
      # ServerlessRestApi is an implicit API created out of Events key under Serverless::Function
      # Find out more about other implicit resources you can reference within SAM
      # https://github.com/awslabs/serverless-application-model/blob/master/docs/internals/generated_resources.rst#api
      HelloWorldApi:
        Description: "API Gateway endpoint URL for Prod stage for functions"
        Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/"

template_user.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  aws-restapi

  Sample SAM Template for aws-restapi

    Globals:
      Function:
        Timeout: 5
        VpcConfig:
            SecurityGroupIds:
              - sg-041f2****cd921e8e
            SubnetIds:
              - subnet-03***b2d
              - subnet-c4d***cb
              - subnet-af5***8
              - subnet-74***f28
              - subnet-d139***c
              - subnet-e9***bd7
      
    
    Resources:
      GetUserRoleByIDFunction:
        Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
        Properties:
          CodeUri: aws-restapi/
          Handler: source/user-role/userrole-getbyid.getUserRoleByID
          Runtime: nodejs14.x
          Events: 
            GetUserRoleByIDAPIEvent:
              Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
              Properties:
                Path: /userrole/getbyid
                Method: get
    
      GetUserRoleByUserFunction:
        Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
        Properties:
          CodeUri: aws-restapi/
          Handler: source/user-role/userrole-getbyuser.getUserRoleByUser
          Runtime: nodejs14.x
          Events:
            GetUserRoleByUserAPIEvent:
              Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
              Properties:
                Path: /userrole/getbyuser
                Method: get
       # DependsOn: GetUserRoleByIDFunction
      GetUserRoleByRoleFunction:
        Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
        Properties:
          CodeUri: aws-restapi/
          Handler: source/user-role/userrole-getbyrole.getAllUsersByRole
          Runtime: nodejs14.x
          Events:
            GetUserRoleByRoleAPIEvent:
              Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
              Properties:
                Path: /userrole/getbyrole
                Method: get
        #DependsOn: GetUserRoleByUserFunction
      SaveUserRoleFunction:
        Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
        Properties:
          CodeUri: aws-restapi/
          Handler: source/user-role/userrole-save.saveUserRole
          Runtime: nodejs14.x
          Events:
            SaveUserRoleAPIEvent:
              Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
              Properties:
                Path: /userrole/save
                Method: post
       # DependsOn: GetUserRoleByRoleFunction
      UpdateUserRoleFunction:
        Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
        Properties:
          CodeUri: aws-restapi/
          Handler: source/user-role/userrole-update.updateeUserRole
          Runtime: nodejs14.x
          Events:
            UpdateUserRoleAPIEvent:
              Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
              Properties:
                Path: /userrole/update
                Method: post
        #DependsOn: SaveUserRoleFunction

template_two.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  aws-restapi

  Sample SAM Template for aws-restapi

Globals:
  Function:
    Timeout: 5
    VpcConfig:
        SecurityGroupIds:
          - sg-041f24xxxxd921e8e
        SubnetIds:
          - subnet-0381xxxd
          - subnet-c4dxxxcb
          - subnet-af5xxxc8
          - subnet-748xxx28
          - subnet-d139xxx9c
          - subnet-e9e8xxx7

Resources:
  GetAllPromotionsFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    
    Properties:
      CodeUri: aws-restapi/
      Handler: source/promotions/promotions-getall.getAllPromotions
      Runtime: nodejs14.x
      Events:
        GetAllPromotionsAPIEvent:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /promotions/getall
            Method: get
  SavePromotionsFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    
    Properties:
      CodeUri: aws-restapi/
      Handler: source/promotions/promotions-save.savePromotions
      Runtime: nodejs14.x
      Events:
        SavePromotionsAPIEvent:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /promotions/save
            Method: post
  UpdatePromotionsFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    
    Properties:
      CodeUri: aws-restapi/
      Handler: source/promotions/promotions-update.updatePromotions
      Runtime: nodejs14.x
      Events:
        UpdatePromotionsAPIEvent:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /promotions/update
            Method: post


  GetAllStaticInfoFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    
    Properties:
      CodeUri: aws-restapi/
      Handler: source/static-info/staticinfo-getall.getAllStaticInfo
      Runtime: nodejs14.x
      Events:
        GetAllStaticInfoAPIEvent:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /staticinfo/getall
            Method: get
  SaveStaticInfoFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    
    Properties:
      CodeUri: aws-restapi/
      Handler: source/static-info/staticinfo-save.saveStaticInfo
      Runtime: nodejs14.x
      Events:
        SaveStaticInfoAPIEvent:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /staticinfo/save
            Method: post
  UpdateStaticInfoFunction:
    Type: AWS::Serverless::Function # More info about Function Resource: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#awsserverlessfunction
    
    Properties:
      CodeUri: aws-restapi/
      Handler: source/static-info/staticinfo-update.updateStaticInfo
      Runtime: nodejs14.x
      Events:
        UpdateStaticInfoAPIEvent:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /staticinfo/update
            Method: post

This worked, but I noticed that API Gateway assigned different URLs for each stack I create. In this example I have two stacks and API Gateway did create 2 URLs.

  1. template.yaml URL - https://ez5khz***.execute-api.us-east-1.amazonaws.com/Prod/
  2. template_user.yaml URL - https://7imy9b6***.execute-api.us-east-1.amazonaws.com/Prod/ . template_two.yaml URL - https://8awey9b6***.execute-api.us-east-1.amazonaws.com/Prod/

I want the URL that was made with template.yaml to be applied to all lambda functions, regardless of which nested stack it is in. I also have a plan to later assign a domain into this.

How I can get this to work under a one URL?

1
amazon-web-servicesaws-lambdaamazon-cloudformationaws-api-gatewayaws-sam
You have only one NestedStack, so I'm not sure what is the issue? Why would you get two APIs from it? - Marcin
@Marcin: Hi Marcin, I am not sure what you meant . I do have many stacks in the real case, here added just two. The API Gateway URL my nested stack get is different from the one my Root stack gets. That is the problem here. - JustCause
Its different because you are create new API. If you want to use the API from the root stack, why not pass its reference to the nested stack as an input parameter to it? - Marcin
@Marcin: To make sure there are no confusions, I added another nested stack - JustCause
@Marcin: I do not have a deep knowledge on this Marcin. I am learning on the go. Do you mind showing me how to do it taking my code as an example? I will greatly appreciate that effort. - JustCause

1 Answers

0
votes

I think Marcin is right in the sense that in your top-level stack you can define your own AWS::Serverless::Api resource. Its a bit more effort than letting SAM do everything for you but it gives you the flexibility you want.

You can pass on the Api ID to other nested stacks using a simple !Ref.

For this to work, in the nested stack you need an ApiId parameter, which you then use in all of your defined lambdas:

Parameters:
   ApiId: ....

.....
Resources:
.....
      Events:
        UpdatePromotionsAPIEvent:
          Type: Api # More info about API Event Source: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#api
          Properties:
            Path: /promotions/update
            Method: post
            RestApiId: !Ref ApiId

I haven't tried this myself, but I think it should work?