Serverless Framework Error: Every Resources object must contain a Type member

Question

I'm trying to mount an EFS to my Lambda function so that I can use large dependencies. So far I've been following this tutorial.

I slightly modified the .yml.

serverless.yml

service: test2EFS

plugins:
  - serverless-pseudo-parameters

custom:
  efsAccessPoint: fsap-00**********
  LocalMountPath: /mnt/efs
  subnetsId: subnet-0b**********
  securityGroup: sg-0b7**********

provider:
  name: aws
  runtime: python3.6
  region: us-east-2

package:
  exclude:
    - node_modules/**
    - .vscode/**
    - .serverless/**
    - .pytest_cache/**
    - __pychache__/**

functions:
  test:
    handler: handler.handler
    environment: # Service wide environment variables
      MNT_DIR: ${self:custom.LocalMountPath}
    vpc:
      securityGroupIds:
        - ${self:custom.securityGroup}
      subnetIds:
        - ${self:custom.subnetsId}
    iamManagedPolicies:
      - arn:aws:iam::aws:policy/AmazonElasticFileSystemClientReadWriteAccess
    events:
      - http:
          path: test
          method: get

resources:
  extensions:
    # Name of function
    test2EFSLambdaFunction:
      Properties:
        FileSystemConfigs:
          - Arn: 'arn:aws:elasticfilesystem:${self:provider.region}:#{AWS::AccountId}:access-point/${self:custom.efsAccessPoint}'
            LocalMountPath: '${self:custom.LocalMountPath}'

Whenever I run severless deploy I get the following error:

Serverless: Uploading artifacts...
Serverless: Uploading service test2EFS.zip file to S3 (926 B)...
Serverless: Validating template...
 
  Error --------------------------------------------------
 
  Error: The CloudFormation template is invalid: Template format error: [/Resources/test2EFSLambdaFunction] Every Resources object must contain a Type member.
      at provider.request.catch (/usr/local/lib/node_modules/serverless/lib/plugins/aws/deploy/lib/validateTemplate.js:20:13)
      at tryCatcher (/usr/local/lib/node_modules/serverless/node_modules/bluebird/js/release/util.js:16:23)
      at Promise._settlePromiseFromHandler (/usr/local/lib/node_modules/serverless/node_modules/bluebird/js/release/promise.js:547:31)
      at Promise._settlePromise (/usr/local/lib/node_modules/serverless/node_modules/bluebird/js/release/promise.js:604:18)
      at Promise._settlePromise0 (/usr/local/lib/node_modules/serverless/node_modules/bluebird/js/release/promise.js:649:10)
      at Promise._settlePromises (/usr/local/lib/node_modules/serverless/node_modules/bluebird/js/release/promise.js:725:18)
      at _drainQueueStep (/usr/local/lib/node_modules/serverless/node_modules/bluebird/js/release/async.js:93:12)
      at _drainQueue (/usr/local/lib/node_modules/serverless/node_modules/bluebird/js/release/async.js:86:9)
      at Async._drainQueues (/usr/local/lib/node_modules/serverless/node_modules/bluebird/js/release/async.js:102:5)
      at Immediate.Async.drainQueues [as _onImmediate] (/usr/local/lib/node_modules/serverless/node_modules/bluebird/js/release/async.js:15:14)
      at runCallback (timers.js:705:18)
      at tryOnImmediate (timers.js:676:5)
      at processImmediate (timers.js:658:5)
      at process.topLevelDomainCallback (domain.js:126:23)

I tried commenting out various parts, and narrowed down the error to somewhere within

resources:
  extensions:
    # Name of function
    test2EFSLambdaFunction:
      Properties:
        FileSystemConfigs:
          - Arn: 'arn:aws:elasticfilesystem:${self:provider.region}:#{AWS::AccountId}:access-point/${self:custom.efsAccessPoint}'
            LocalMountPath: '${self:custom.LocalMountPath}'

besides renaming (what I think is) an insignificant function name, this code snippet is the same as the reference. I tried hard coding #{AWS::AccountId} based on my account ID, but that didn't work. I'm now a bit stumped.

Answer 1

Normally CloudFormation expects a Type parameter in a resource definition, e.g. Type: AWS::Lambda::Function, hence why you're seeing the error. In your case you're using the Override AWS CloudFormation Resource functionality by Serverless though, i.e. the name needs to exactly match the normalized function name Serverless assigns (see the doc linked above), in your case this would be TestLambdaFunction.

Change your code to:

resources:
  extensions:
    TestLambdaFunction:
      Properties:
        [...]