serverless.yml

service: twitter-backend
frameworkVersion: '2'

plugins:
  - serverless-appsync-plugin
  - serverless-iam-roles-per-function
  - serverless-export-env
  - serverless-layers

provider:
  name: aws
  runtime: nodejs12.x
  region: eu-west-1
  environment:
    STAGE: ${self:custom.stage}
    AWS_NODEJS_CONNECTION_REUSE_ENABLED: "1"

package:
  exclude:
    - package-lock.json
    - package.json

custom:
  region: ${opt.region, self:provider.region}
  stage: ${opt:stage, self:provider.stage}
  appSync:
    - ${file(serverless.appsync-api.yml)}
  serverless-layers:
    layersDeploymentBucket: ${ssm:/appsyncmasterclass/${self:custom.stage}/layer-deployment-bucket-twitter}

functions:
  confirmUserSignup:
    handler: functions/confirm-user-signup.handler
    environment:
      USERS_TABLE: !Ref UsersTable
    iamRoleStatements:
      - Effect: Allow
        Action: dynamodb:PutItem
        Resource: !GetAtt UsersTable.Arn

  getImageUploadUrl:
    handler: functions/get-image-upload-url.handler
    environment:
      BUCKET_NAME: !Ref AssetsBucket
    iamRoleStatements:
      - Effect: Allow
        Action:
          - s3:PutObject
          - s3:PutObjectAcl
        Resource: !Sub ${AssetsBucket.Arn}/* # every object inside this bucket

  tweetFunction:
    handler: functions/tweet.handler
    environment:
      USERS_TABLE: !Ref UsersTable
      TWEETS_TABLE: !Ref TweetsTable
      TIMELINES_TABLE: !Ref TimelinesTable
    iamRoleStatements:
      - Effect: Allow
        Action: dynamodb:UpdateItem
        Resource: !GetAtt UsersTable.Arn
      - Effect: Allow
        Action: dynamodb:PutItem
        Resource:
          - !GetAtt TweetsTable.Arn
          - !GetAtt TimelinesTable.Arn

  retweetFunction:
    handler: functions/retweet.handler
    environment:
      USERS_TABLE: !Ref UsersTable
      TWEETS_TABLE: !Ref TweetsTable
      TIMELINES_TABLE: !Ref TimelinesTable
      RETWEETS_TABLE: !Ref RetweetsTable
    iamRoleStatements:
      - Effect: Allow
        Action: dynamodb:GetItem
        Resource: !GetAtt TweetsTable.Arn
      - Effect: Allow
        Action: dynamodb:UpdateItem
        Resource:
          - !GetAtt UsersTable.Arn
          - !GetAtt TweetsTable.Arn
      - Effect: Allow
        Action: dynamodb:PutItem
        Resource:
          - !GetAtt TweetsTable.Arn
          - !GetAtt TimelinesTable.Arn
          - !GetAtt RetweetsTable.Arn

  replyFunction:
    handler: functions/reply.handler
    environment:
      USERS_TABLE: !Ref UsersTable
      TWEETS_TABLE: !Ref TweetsTable
      TIMELINES_TABLE: !Ref TimelinesTable
    iamRoleStatements:
      - Effect: Allow
        Action: dynamodb:GetItem
        Resource: !GetAtt TweetsTable.Arn
      - Effect: Allow
        Action: dynamodb:UpdateItem
        Resource:
          - !GetAtt UsersTable.Arn
          - !GetAtt TweetsTable.Arn
      - Effect: Allow
        Action: dynamodb:PutItem
        Resource:
          - !GetAtt TweetsTable.Arn
          - !GetAtt TimelinesTable.Arn

  unretweetFunction:
    handler: functions/unretweet.handler
    environment:
      USERS_TABLE: !Ref UsersTable
      TWEETS_TABLE: !Ref TweetsTable
      TIMELINES_TABLE: !Ref TimelinesTable
      RETWEETS_TABLE: !Ref RetweetsTable
    iamRoleStatements:
      - Effect: Allow
        Action: dynamodb:GetItem
        Resource: !GetAtt TweetsTable.Arn
      - Effect: Allow
        Action: dynamodb:Query
        Resource: !Sub "${TweetsTable.Arn}/index/retweetsByCreator"
      - Effect: Allow
        Action: dynamodb:UpdateItem
        Resource:
          - !GetAtt UsersTable.Arn
          - !GetAtt TweetsTable.Arn
      - Effect: Allow
        Action: dynamodb:DeleteItem
        Resource:
          - !GetAtt TweetsTable.Arn
          - !GetAtt TimelinesTable.Arn
          - !GetAtt RetweetsTable.Arn

  distributeTweets:
    handler: functions/distribute-tweets.handler
    environment:
      RELATIONSHIPS_TABLE: !Ref RelationshipsTable
      TIMELINES_TABLE: !Ref TimelinesTable
    events:
      - stream:
          type: dynamodb
          arn: !GetAtt TweetsTable.StreamArn
    iamRoleStatements:
      - Effect: Allow
        Action:
          - dynamodb:PutItem
          - dynamodb:DeleteItem
          - dynamodb:BatchWriteItem
        Resource: !GetAtt TimelinesTable.Arn
      - Effect: Allow
        Action: dynamodb:Query
        Resource: !Sub "${RelationshipsTable.Arn}/index/byOtherUser"

  distributeTweetsToFollower:
    handler: functions/distribute-tweets-to-follower.handler
    environment:
      TWEETS_TABLE: !Ref TweetsTable
      TIMELINES_TABLE: !Ref TimelinesTable
      MAX_TWEETS: "100"
    events:
      - stream:
          type: dynamodb
          arn: !GetAtt RelationshipsTable.StreamArn
    iamRoleStatementsName: ${self:service}-${self:custom.stage}-distributeTweetsToFollower
    iamRoleStatements:
      - Effect: Allow
        Action: dynamodb:Query
        Resource:
          - !Sub "${TweetsTable.Arn}/index/byCreator"
          - !Sub "${TimelinesTable.Arn}/index/byDistributedFrom"
      - Effect: Allow
        Action:
          - dynamodb:BatchWriteItem
          - dynamodb:PutItem
          - dynamodb:DeleteItem
        Resource: !GetAtt TimelinesTable.Arn

  syncUsersToAlgolia:
    handler: functions/sync-users-to-algolia.handler
    events:
      - stream:
          type: dynamodb
          arn: !GetAtt UsersTable.StreamArn
    iamRoleStatements:
      - Effect: Allow
        Action: ssm:GetParameters
        Resource:
          - !Sub arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/${self:custom.stage}/algolia-app-id
          - !Sub arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/${self:custom.stage}/algolia-admin-key

  syncTweetsToAlgolia:
    handler: functions/sync-tweets-to-algolia.handler
    events:
      - stream:
          type: dynamodb
          arn: !GetAtt TweetsTable.StreamArn
    iamRoleStatements:
      - Effect: Allow
        Action: ssm:GetParameters
        Resource:
          - !Sub arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/${self:custom.stage}/algolia-app-id
          - !Sub arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/${self:custom.stage}/algolia-admin-key

  search:
    handler: functions/search.handler
    iamRoleStatements:
      - Effect: Allow
        Action: ssm:GetParameters
        Resource:
          - !Sub arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/${self:custom.stage}/algolia-app-id
          - !Sub arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/${self:custom.stage}/algolia-admin-key

  getHashTag:
    handler: functions/get-hash-tag.handler
    iamRoleStatements:
      - Effect: Allow
        Action: ssm:GetParameters
        Resource:
          - !Sub arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/${self:custom.stage}/algolia-app-id
          - !Sub arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/${self:custom.stage}/algolia-admin-key

  notify:
    handler: functions/notify.handler
    environment:
      GRAPHQL_API_URL: !GetAtt AppsyncmasterclassGraphQlApi.GraphQLUrl
      TWEETS_TABLE: !Ref TweetsTable
      USERS_TABLE: !Ref UsersTable
    events:
      - stream:
          type: dynamodb
          arn: !GetAtt TweetsTable.StreamArn
    iamRoleStatements:
      - Effect: Allow
        Action: appsync:GraphQL
        Resource: !Sub ${AppsyncmasterclassGraphQlApi.Arn}/*
      - Effect: Allow
        Action: dynamodb:GetItem
        Resource: !GetAtt TweetsTable.Arn
      - Effect: Allow
        Action: dynamodb:Query
        Resource: !Sub ${UsersTable.Arn}/index/byUsername

  notifyLiked:
    handler: functions/notify-liked.handler
    environment:
      GRAPHQL_API_URL: !GetAtt AppsyncmasterclassGraphQlApi.GraphQLUrl
      TWEETS_TABLE: !Ref TweetsTable
    events:
      - stream:
          type: dynamodb
          arn: !GetAtt LikesTable.StreamArn
    iamRoleStatements:
      - Effect: Allow
        Action: appsync:GraphQL
        Resource: !Sub ${AppsyncmasterclassGraphQlApi.Arn}/*
      - Effect: Allow
        Action: dynamodb:GetItem
        Resource: !GetAtt TweetsTable.Arn

resources:
 Resources:
  UsersTable:
    Type: AWS::DynamoDB::Table
    Properties:
      BillingMode: PAY_PER_REQUEST
      KeySchema:
        - AttributeName: id
          KeyType: HASH
      AttributeDefinitions:
        - AttributeName: id
          AttributeType: S
        - AttributeName: username
          AttributeType: S
      GlobalSecondaryIndexes:
        - IndexName: byUsername
          KeySchema:
            - AttributeName: username
              KeyType: HASH
          Projection:
            ProjectionType: ALL
      StreamSpecification:
          StreamViewType: NEW_AND_OLD_IMAGES
      Tags:
        - Key: Environment
          Value: ${self:custom.stage}
        - Key: Name
          Value: users-table

  TweetsTable:
    Type: AWS::DynamoDB::Table
    Properties:
      BillingMode: PAY_PER_REQUEST
      KeySchema:
        - AttributeName: id
          KeyType: HASH
      AttributeDefinitions:
        - AttributeName: id
          AttributeType: S
        - AttributeName: creator
          AttributeType: S
        - AttributeName: retweetOf
          AttributeType: S
        - AttributeName: inReplyToTweet
          AttributeType: S
      GlobalSecondaryIndexes:
        - IndexName: byCreator
          KeySchema:
            - AttributeName: creator
              KeyType: HASH
            - AttributeName: id
              KeyType: RANGE
          Projection:
            ProjectionType: ALL
        - IndexName: retweetsByCreator
          KeySchema:
            - AttributeName: creator
              KeyType: HASH
            - AttributeName: retweetOf
              KeyType: RANGE
          Projection:
            ProjectionType: ALL
        - IndexName: repliesForTweet
          KeySchema:
            - AttributeName: inReplyToTweet
              KeyType: HASH
            - AttributeName: id
              KeyType: RANGE
          Projection:
            ProjectionType: ALL
      StreamSpecification:
          StreamViewType: NEW_AND_OLD_IMAGES
      Tags:
        - Key: Environment
          Value: ${self:custom.stage}
        - Key: Name
          Value: tweets-table

  TimelinesTable:
    Type: AWS::DynamoDB::Table
    Properties:
      BillingMode: PAY_PER_REQUEST
      KeySchema:
        - AttributeName: userId
          KeyType: HASH
        - AttributeName: tweetId
          KeyType: RANGE
      AttributeDefinitions:
        - AttributeName: userId
          AttributeType: S
        - AttributeName: tweetId
          AttributeType: S
        - AttributeName: distributedFrom
          AttributeType: S
      GlobalSecondaryIndexes:
        - IndexName: byDistributedFrom
          KeySchema:
            - AttributeName: userId
              KeyType: HASH
            - AttributeName: distributedFrom
              KeyType: RANGE
          Projection:
            ProjectionType: ALL
      Tags:
        - Key: Environment
          Value: ${self:custom.stage}
        - Key: Name
          Value: timelines-table

  LikesTable:
    Type: AWS::DynamoDB::Table
    Properties:
      BillingMode: PAY_PER_REQUEST
      KeySchema:
        - AttributeName: userId
          KeyType: HASH
        - AttributeName: tweetId
          KeyType: RANGE
      AttributeDefinitions:
        - AttributeName: userId
          AttributeType: S
        - AttributeName: tweetId
          AttributeType: S
      StreamSpecification:
          StreamViewType: NEW_AND_OLD_IMAGES
      Tags:
        - Key: Environment
          Value: ${self:custom.stage}
        - Key: Name
          Value: likes-table

  RetweetsTable:
    Type: AWS::DynamoDB::Table
    Properties:
      BillingMode: PAY_PER_REQUEST
      KeySchema:
        - AttributeName: userId
          KeyType: HASH
        - AttributeName: tweetId
          KeyType: RANGE
      AttributeDefinitions:
        - AttributeName: userId
          AttributeType: S
        - AttributeName: tweetId
          AttributeType: S
      Tags:
        - Key: Environment
          Value: ${self:custom.stage}
        - Key: Name
          Value: retweets-table

  RelationshipsTable:
      Type: AWS::DynamoDB::Table
      Properties:
        BillingMode: PAY_PER_REQUEST
        KeySchema:
          - AttributeName: userId
            KeyType: HASH
          - AttributeName: sk
            KeyType: RANGE
        AttributeDefinitions:
          - AttributeName: userId
            AttributeType: S
          - AttributeName: sk
            AttributeType: S
          - AttributeName: otherUserId
            AttributeType: S
        GlobalSecondaryIndexes:
          - IndexName: byOtherUser
            KeySchema:
              - AttributeName: otherUserId
                KeyType: HASH
              - AttributeName: sk
                KeyType: RANGE
            Projection:
              ProjectionType: ALL
        StreamSpecification:
          StreamViewType: NEW_AND_OLD_IMAGES
        Tags:
          - Key: Environment
            Value: ${self:custom.stage}
          - Key: Name
            Value: relationships-table

  NotificationsTable:
      Type: AWS::DynamoDB::Table
      Properties:
        BillingMode: PAY_PER_REQUEST
        KeySchema:
          - AttributeName: id
            KeyType: HASH
          - AttributeName: userId
            KeyType: RANGE
        AttributeDefinitions:
          - AttributeName: id
            AttributeType: S
          - AttributeName: userId
            AttributeType: S
        GlobalSecondaryIndexes:
          - IndexName: byUserId
            KeySchema:
              - AttributeName: userId
                KeyType: HASH
              - AttributeName: id
                KeyType: RANGE
            Projection:
              ProjectionType: ALL
        Tags:
          - Key: Environment
            Value: ${self:custom.stage}
          - Key: Name
            Value: notifications-table

  CognitoUserPool:
    Type: AWS::Cognito::UserPool
    Properties:
      AutoVerifiedAttributes:
        - email
      Policies:
        PasswordPolicy:
          MinimumLength: 8
          RequireLowercase: false
          RequireNumbers: false
          RequireUppercase: false
          RequireSymbols: false
      UsernameAttributes:
        - email
      Schema:
        - AttributeDataType: String
          Name: name
          Required: false
          Mutable: true
      LambdaConfig:
        PostConfirmation: !GetAtt ConfirmUserSignupLambdaFunction.Arn

  # Grants CognitoUserPool permission to call the ConfirmUserSignupLambdaFunction
  UserPoolInvokeConfirmUserSignupLambdaPermission:
    Type: AWS::Lambda::Permission
    Properties:
      Action: lambda:invokeFunction
      FunctionName: !Ref ConfirmUserSignupLambdaFunction
      Principal: cognito-idp.amazonaws.com
      SourceArn: !GetAtt CognitoUserPool.Arn

  # Amazon Cognito User Pool Client provides a way to generate authentication tokens used to authorize a user for an application.
  WebUserPoolClient:
    Type: AWS::Cognito::UserPoolClient
    Properties:
      UserPoolId: !Ref CognitoUserPool
      ClientName: web
      ExplicitAuthFlows:
        - ALLOW_USER_SRP_AUTH
        - ALLOW_USER_PASSWORD_AUTH
        - ALLOW_REFRESH_TOKEN_AUTH
      PreventUserExistenceErrors: ENABLED

  AssetsBucket:
    Type: AWS::S3::Bucket
    Properties:
      AccelerateConfiguration:
        AccelerationStatus: Enabled
      CorsConfiguration:
        CorsRules:
          - AllowedMethods:
              - GET
              - PUT
            AllowedOrigins:
              - '*' # in prod, don't want this
            AllowedHeaders:
              - '*' # in prod, don't want this

 Outputs:
    AwsRegion:
      Value: ${self:custom.region}

    CognitoUserPoolId:
      Value: !Ref CognitoUserPool

    WebCognitoUserPoolClientId:
      Value: !Ref WebUserPoolClient

    ApiUrl:
      Value: !GetAtt AppsyncmasterclassGraphQlApi.GraphQLUrl