how to include multiple resource files in SAM template.yml

Question

I want to write my cloud formation yml file in a different file and load them separately. It is easy to do it in the serverless framework but I couldn't figure it out how to do it with SAM. Would you mind help me how to do it?

I provided a copy of the project below:

https://github.com/day2daychallenge/nest_application.git

my template.yml file:

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  Sample SAM Template

# Create our resources with separate CloudFormation templates
resources:
  Resources:
    # Lambda function
    - ${file(resources/lambda-functions.yml)}

My resource file(lambda-functions.yml) is as below:

  HelloWorldFunction:
    Type: AWS::Serverless::Function 
    Properties:
      CodeUri: hello-world/
      Handler: app.lambdaHandler
      Runtime: nodejs12.x
      Events:
        HelloWorld:
          Type: Api 
          Properties:
            Path: /helloworld
            Method: get

my folder structure.

Edit4:

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  Sample SAM Template

# Create our resources with separate CloudFormation templates resources:
Resources:
  yourApplicationAliasName:
    Type: AWS::Serverless::Application
    Properties:
      # Lambda function
      Location: ./resources/lambda-functions.yml

lambda-functions.yml content:

AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: AWS Lambda function.
Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function 
    Properties:
      CodeUri: ../hello-world/
      Handler: app.lambdaHandler
      Runtime: nodejs12.x
      Events:
        HelloWorld:
          Type: Api 
          Properties:
            Path: /helloworld
            Method: get

my buildspec.yml file:

version: 0.2
phases:
  install:
    runtime-versions:
      nodejs: 12
  pre_build:
    commands:
      - echo Install source NPM dependencies...
      - npm install
  build:
    commands:
      - echo packaging files by using cloudformation...
      - export BUCKET=sls-simple
      - aws cloudformation package --template-file template.yml --s3-bucket $BUCKET --output-template-file outputtemplate.yml
    finally:
      - echo This always runs even if the install command fails
artifacts:
  type: zip
  files:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
    - template.yml
    - outputtemplate.yml

Error1 in build(solved):

Transform AWS::Serverless-2016-10-31 failed with: Invalid Serverless Application Specification document. Number of errors found: 1. Structure of the SAM template is invalid. 'Resources' section is required Created time

Error2 in deployment( execute changeset)

The following resource(s) failed to create: [yourApplicationAliasName]. . Rollback requested by user. 2020-03-06 13:37:38 UTC+0800 yourApplicationAliasName CREATE_FAILED Template format error: At least one Resources member must be defined.

Error3 in the build section

[Container] 2020/03/07 15:24:43 Running command aws cloudformation package --template-file template.yml --s3-bucket $BUCKET --output-template-file outputtemplate.yml

Unable to upload artifact ./resources/lambda-functions.yml referenced by Location parameter of yourApplicationAliasName resource. Unable to upload artifact hello-world/ referenced by CodeUri parameter of HelloWorldFunction resource. Parameter CodeUri of resource HelloWorldFunction refers to a file or folder that does not exist /codebuild/output/src606023065/src/resources/hello-world

Error4: Code build is successful now, and I get below error during deployment.

Template format error: At least one Resources member must be defined.

The following resource(s) failed to create: [yourApplicationAliasName]. . Rollback requested by user.

Answer 1

you can use the Location property ( https://docs.aws.amazon.com/de_de/serverless-application-model/latest/developerguide/serverless-sam-template-nested-applications.html)

In your case should be something like

template.yml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  Sample SAM Template

# Create our resources with separate CloudFormation templates resources:
Resources:
  yourApplicationAliasName:
    Type: AWS::Serverless::Application
    Properties:
      # Lambda function
      Location: ./resources/lambda-functions.yml

and the lambda-functions.yml file

AWSTemplateFormatVersion: '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Description: AWS Lambda function.
Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function 
    Properties:
      CodeUri: hello-world/
      Handler: app.lambdaHandler
      Runtime: nodejs12.x
      Events:
        HelloWorld:
          Type: Api 
          Properties:
            Path: /helloworld
            Method: get

try to use be sam command for packaging as below:

sam package --template template.yml --output-template-file outputtemplate.yml --s3-bucket your-bucket-name

then you need to deploy it:

sam deploy --template-file outputtemplate.yml --stack-name your-bucket-name --capabilities CAPABILITY_IAM CAPABILITY_AUTO_EXPAND

** do not forget to remove your previous stack if there is any.

Thx!.........

Answer 2

EDIT: This should work now: https://github.com/aws/aws-sam-cli/issues/1213#issuecomment-789975452

@amir would be curious to hear from you as to whether you sorted this out. For those searching for this, as far as I've seen, this won't work because nested stacks don't appear to support transforms (yet) in CloudFormation.

This issue mentions that nested stacks can't use transforms like SAM, and in this closed GitHub issue, one of the maintainers of the AWS SAM CLI noted "Closing as we don't yet support Nested Templates in SAM build or any other commands except package. We should create a general issue for this support."

Please give thumbs up to the CF roadmap to ask AWS to support this.