serverless.yml

service: instawat

provider:
  name: aws
  runtime: python2.7
  region: us-east-1

  # Set up IAM authorization for the Lambda functions. They get full access
  # to the S3 bucket and DynamoDB table.
  iamRoleStatements:
    - Effect: Allow
      Action:
        - "*"
      Resource:
        - "arn:aws:s3:::${self:custom.bucket}/*"
        - "arn:aws:dynamodb:*:*:table/instawat"
        - "arn:aws:dynamodb:*:*:table/instawat/*"

  # These environment variables are from the Python code to determine the
  # S3 bucket and DynamoDB table to use for storage.
  environment:
    BUCKET_NAME: ${self:custom.bucket}
    TABLE_NAME: instawat

# The serverless-wsgi plugin allows us to use Flask for the web app.
plugins:
  - serverless-wsgi

# Exclude anything you do not need. A smaller package bundle means less latency
# on cold invocation.
package:
  exclude:
    - images/**
    - node_modules/**

functions:
  # PART 1: APP
  app:
    handler: wsgi.handler
    events:
      - http: ANY /

  # PART 2: DOWNLOADER
  downloader:
    timeout: 30
    handler: downloader.handler
    events:
      - stream:
          # Listen for stream events when new items are added to DynamoDB.
          type: dynamodb
          # Limit the number of events to process per invocation.
          batchSize: 10
          arn:
            Fn::GetAtt:
              - InstawatTable
              - StreamArn

  # PART 3: THE WATIFIER
  watifier:
    # We'll give it some more memory/CPU as it does a bit more work.
    memorySize: 512
    timeout: 30
    handler: watifier.handler
    events:
      - s3:
          # This statement also creates the S3 bucket.
          bucket: ${self:custom.bucket}
          rules:
            # Only trigger events for originals, otherwise watified photos
            # would be watified, double-watified photos would be triple-watified
            # and all hell would break loose.
            # Your AWS bill would suffer, at the very least.
            - prefix: original/

custom:
  # The name of the bucket must be provided on the CLI as --bucket_name.
  bucket: ${opt:bucket_name}
  wsgi:
    app: app.app

# This section is pretty hairy, blame CloudFormation.
resources:
  Resources:
    # Create a table in DynamoDB.
    InstawatTable:
      Type: AWS::DynamoDB::Table
      Properties:
        TableName: instawat

        # A list of the attributes that will be used for indexes.
        AttributeDefinitions:
          - AttributeName: url
            AttributeType: S
          - AttributeName: created_at_date
            AttributeType: S
          - AttributeName: created_at_time
            AttributeType: N

        # The url is the primary key.
        KeySchema:
          - AttributeName: url
            KeyType: HASH

        # We want to show a list of the latest wats created today. For
        # this purpose, we will need a GSI that sorts by timestamp.
        GlobalSecondaryIndexes:
          - IndexName: created_at-index
            KeySchema:
            - AttributeName: created_at_date
              KeyType: HASH
            - AttributeName: created_at_time
              KeyType: RANGE
            Projection:
              ProjectionType: ALL
            ProvisionedThroughput:
              ReadCapacityUnits: 1
              WriteCapacityUnits: 1
        ProvisionedThroughput:
          ReadCapacityUnits: 1
          WriteCapacityUnits: 1

        # Stream new items to the downloader.
        StreamSpecification:
          StreamViewType: NEW_IMAGE