Description: SAM + Lambda + EFS

Parameters:
  ExistingEfsFileSystem:
    Type: String

  SecurityGroupIds:
    Type: List<AWS::EC2::SecurityGroup::Id>
    Description: Security Group IDs that Lambda will use

  VpcSubnetIds:
    Type: List<AWS::EC2::Subnet::Id>
    Description: VPC Subnet IDs that Lambda will use

Resources:
  EfsFileSystem:
    Type: AWS::EFS::FileSystem

  MountTarget:
    Type: AWS::EFS::MountTarget
    Properties:
      FileSystemId: !Ref EfsFileSystem
      SubnetId: subnet-abc123
      SecurityGroups: !Ref SecurityGroupIds

  AccessPoint:
    Type: AWS::EFS::AccessPoint
    Properties:
      FileSystemId: !Ref EfsFileSystem

  LambdaFunctionWithEfs:
    Type: AWS::Serverless::Function
    Properties:
      InlineCode: |
        const fs = require('fs')
        const path = require('path')
        const efsMountPath = '/mnt/efs'

        exports.handler = async (event, context, callback) => {
        const directory = path.join(efsMountPath, event.body)
        const files = fs.readdirSync(directory)
        return files
        }
      Handler: index.handler
      MemorySize: 128
      Runtime: nodejs12.x
      Timeout: 3
      VpcConfig:
        SecurityGroupIds: !Ref SecurityGroupIds
        SubnetIds: !Ref VpcSubnetIds
      FileSystemConfigs:
      - Arn: !GetAtt AccessPoint.Arn
        LocalMountPath: /mnt/EFS