/// <summary> /// Creates a log shipper that does nothing. It's like sending the logs to /dev/null. /// </summary> /// <param name="scope"></param> /// <returns></returns> public static Function CreateDevNullLogShipper(Construct scope) { return(new Function(scope, "DevNullLogShipper", new FunctionProps { Runtime = Runtime.NODEJS_10_X, Handler = "index.handler", Description = "Forwards kinesis records to nowhere. It simply logs that it received something.", MemorySize = 128, Code = Code.FromInline(EmbeddedResourceReader.Read("Resources.DevNullLogShipper.js")) })); }
/// <summary> /// Constructor. /// </summary> /// <param name="scope"></param> /// <param name="id"></param> /// <param name="props"></param> public LogAggregator(Construct scope, string id, LogAggregatorProps props) : base(scope, id) { // The Kinesis stream that will receive all lambda logs. var kinesisStream = new Amazon.CDK.AWS.Kinesis.Stream(this, "Stream", props.KinesisStreamProps); // Forward all records from kinesis to the log shipper. props.LogShipper.AddEventSource(new KinesisEventSource(kinesisStream, new KinesisEventSourceProps { BatchSize = props.KinesisBatchSize, MaxBatchingWindow = props.KinesisMaxBatchingWindow, StartingPosition = StartingPosition.TRIM_HORIZON, })); // Create a role (containing a policy) that can be assumed by CloudWatch logs to put records in Kinesis. var statement = new PolicyStatement(); statement.AddActions(new[] { "kinesis:PutRecords", "kinesis:PutRecord" }); statement.AddResources(new[] { kinesisStream.StreamArn }); var cloudWatchLogsToKinesisRole = new Role(this, "CloudWatchLogsToKinesis", new RoleProps { AssumedBy = new ServicePrincipal("logs.amazonaws.com") }); cloudWatchLogsToKinesisRole.AttachInlinePolicy(new Policy(this, "CanPutRecordsInKinesis", new PolicyProps { Statements = new[] { statement } })); // This CloudWatch rule will trigger whenever a new LogGroup is created. This assumes // that CloudTrail is enabled. var createLogGroupEventRule = new Rule(this, "CreateLogGroupEvent", new RuleProps { Description = "Fires whenever CloudTrail detects that a log group is created", EventPattern = new EventPattern { Source = new[] { "aws.logs" }, DetailType = new[] { "AWS API Call via CloudTrail" }, Detail = new Dictionary <string, object> { { "eventSource", new string[] { "logs.amazonaws.com" } }, { "eventName", new string[] { "CreateLogGroup" } }, } } }); if (props.CloudWatchLogRetentionInDays.HasValue) { var setLogGroupExpirationLambda = new Function(this, "SetLogGroupExpiration", new FunctionProps { Runtime = Runtime.NODEJS_10_X, Handler = "index.handler", Description = $"Sets the log retention policy to {props.CloudWatchLogRetentionInDays} days when a log group is created.", MemorySize = 128, Environment = new Dictionary <string, string> { { "retention_days", props.CloudWatchLogRetentionInDays.Value.ToString() }, { "prefix", props.LogGroupsPrefix }, }, Code = Code.FromInline(EmbeddedResourceReader.Read("Resources.SetExpiry.js")) }); // This lambda must be able to change the logs retention policy. setLogGroupExpirationLambda.AddToRolePolicy(new PolicyStatement(new PolicyStatementProps { Effect = Effect.ALLOW, Actions = new[] { "logs:PutRetentionPolicy" }, Resources = new[] { "*" }, })); // This lambda should be invoked automatically when a log group is created. createLogGroupEventRule.AddTarget(new LambdaFunction(setLogGroupExpirationLambda)); } var excludedLogGroups = props.LogShipper == null ? "" : $"/aws/lambda/{props.LogShipper.FunctionName}"; // This function will be invoked whenever a CloudWatch log group is created. It will // subscribe the log group to our Kinesis Data Stream so that all logs end up in the // DataStream. var subscribeLogGroupsToKinesisLambda = new Function(this, "SubscribeLogGroupsToKinesis", new FunctionProps { Runtime = Runtime.NODEJS_10_X, Handler = "index.handler", Description = "Subscribe logs to the Kinesis stream", MemorySize = 128, Environment = new Dictionary <string, string> { { "arn", kinesisStream.StreamArn }, { "role_arn", cloudWatchLogsToKinesisRole.RoleArn }, { "prefix", props.LogGroupsPrefix }, { "excluded_log_groups", excludedLogGroups }, { "filter_pattern", props.CloudWatchLogsFilterPattern.ToString() }, }, Code = Code.FromInline(EmbeddedResourceReader.Read("Resources.SubscribeLogGroupsToKinesis.js")) }); subscribeLogGroupsToKinesisLambda.AddToRolePolicy(new PolicyStatement(new PolicyStatementProps { Effect = Effect.ALLOW, Actions = new [] { "logs:PutSubscriptionFilter" }, Resources = new[] { "*" }, })); subscribeLogGroupsToKinesisLambda.AddToRolePolicy(new PolicyStatement(new PolicyStatementProps { Effect = Effect.ALLOW, Actions = new[] { "iam:PassRole" }, Resources = new[] { "*" }, })); createLogGroupEventRule.AddTarget(new LambdaFunction(subscribeLogGroupsToKinesisLambda)); }