AWSTemplateFormatVersion: 2010-09-09
Transform: AWS::Serverless-2016-10-31
Description: >
  Log Processing utilities stack.
  Provides a dedicated Kinesis stream for log ingestion.
  Subscribe new and existing Lambda function logs named `Airline` to Kinesis
  and only log entries that have `REPORT` or `MONITORING` as strings
  Expire ALL log entries after 14 days
  Creates Custom Metrics for Memory Used, Size, and Estimated Cost for each function and version
  Also creates custom metrics based on "MONITORING|<metric_value>|<metric_unit>|<metric_name>|<namespace>|<dimensions>" format
Resources:
  # Kinesis Stream that will receive Logs from CloudWatch Logs
  LogProcessingStream:
    Type: AWS::Kinesis::Stream
    Properties:
      RetentionPeriodHours: 48
      ShardCount: 1

  # Subscribe new and existing CloudWatch Log groups to ship logs to Kinesis
  SubscribeLogsToProcessingStream:
    Type: AWS::Serverless::Application
    Properties:
      Location:
        ApplicationId: arn:aws:serverlessrepo:us-east-1:374852340823:applications/auto-subscribe-log-group-to-arn
        SemanticVersion: 1.11.1
      Parameters:
        # The ARN of the Lambda function or Kinesis stream to subscribe a newly created CloudWatch log group to
        DestinationArn: !Sub ${LogProcessingStream.Arn}
        ## Disables processing of own logs
        ExcludePrefix: "ProcessCustomMetricsAsync" # Uncomment to override default value
        # Only subscribe to functions created for this project
        ## Otherwise we'd override all CloudWatch Logs by subscribing to our Kinesis
        Prefix: "/aws/lambda/monitoring-app" # Uncomment to override default value
        # Only captures Custom Metrics and INFO|WARN|ERROR log events; reduces cost and unnecessary noise
        FilterPattern:  "?INFO ?ERROR ?WARN ?REPORT ?MONITORING" # "{ $._logLevel != \"debug\" || $.MetricData IS TRUE }" in cases of custom consumer applications.

  # SAR App that will consume from Kinesis stream and create Custom Metrics
  ProcessCustomMetricsAsync:
    Type: AWS::Serverless::Application
    Properties:
      Location:
        ApplicationId: arn:aws:serverlessrepo:us-east-1:374852340823:applications/async-custom-metrics
        SemanticVersion: 1.7.0
      Parameters:
        # What's the event source you will intend to use? If logs are pushed from CloudWatch Logs to Lambda directly, then use 'Lambda'. If logs are pushed to a Kinesis Stream first, then use 'Kinesis'. Other event sources are not supported (yet).
        EventSourceType: "Kinesis" # Uncomment to override default value
        # (optional) Only relevant to the Kinesis event source type. The ARN to the Kinesis stream to  subscribe the function to.
        KinesisStreamArn: !Sub ${LogProcessingStream.Arn} # Uncomment to override default value
        # (optional) Only relevant to the Kinesis event source type. The batch size to use for the  subscription.
        # KinesisStreamBatchSize: '100' # Uncomment to override default value
        # (optional) Timeout for the Lambda function that would ship metrics to CloudWatch. Defaults to 30s.
        # TimeoutSeconds: '30' # Uncomment to override default value
        # (optional) Whether to report init duration for Lambda functions as metrics. Allowed values are "true" or "false".
        RecordLambdaColdStartMetric: 'true' # Uncomment to override default value
        # (optional) Whether to report estimated cost for Lambda functions as metrics. Allowed values are "true" or "false".
        RecordLambdaCostMetric: 'true' # Uncomment to override default value
        # (optional) Whether to collect Lambda usage metrics (i.e. billed duration, memory size,  max memory used) from the logs and turn them into metrics. Allowed values are "true" or "false".
        RecordLambdaUsageMetrics: 'true' # Uncomment to override default value

#  ProcessLogAndMetricsFunction:
#    Type: AWS::Serverless::Function
#    Properties:
#      Handler: src/handlers/index.handler
#      Description: Lambda function to parse logs from Kinesis Stream and either publish as CloudWatch Custom Metric or index logs on Elasticsearch.
#      Runtime: nodejs12.x
#      Timeout: 100
#      Tracing: Active
#      MemorySize: 1024
#      Environment:
#        Variables:
#          ENABLE_DEBUG: false
#          RECORD_LAMBDA_COLD_START_METRIC: true
#          RECORD_LAMBDA_COST_METRIC: true
#      Policies:
        #- ElasticsearchHttpPostPolicy: *
        #    DomainName: *
#        - CloudWatchPutMetricPolicy: {}
#      Events:
#        LogProcessingStream:
#          Type: Kinesis
#          Properties:
#            Stream: !Sub ${LogProcessingStream.Arn}
#            StartingPosition: LATEST
#            BatchSize: 10
#            MaximumBatchingWindowInSeconds: 10
#            Enabled: true

Outputs:
  LogProcessingStream:
    Value: !Sub ${LogProcessingStream.Arn}
    Description: Kinesis Stream used for log processing