LogGroup

Source: src/AWS/Logs/LogGroup.ts

A CloudWatch Logs log group — the container for log streams and the unit that retention, encryption, metric filters, and subscriptions attach to.

Creating Log Groups

ECS Task Log Group

const logs = yield* LogGroup("TaskLogs", {
  retention: "7 days",
});

Encrypted Log Group with Deletion Protection

const key = yield* AWS.KMS.Key("LogsKey");
const logs = yield* LogGroup("AuditLogs", {
  retention: "30 days",
  kmsKeyId: key.keyArn,
  deletionProtectionEnabled: true,
});

Writing Custom Log Events

Declare a LogStream and use the PutLogEvents binding inside a Lambda function (or the batching LogEventSink for high-volume streams).

// init
const logGroup = yield* AWS.Logs.LogGroup("AuditLogs", {
  retention: "30 days",
});
const stream = yield* AWS.Logs.LogStream("AuditStream", {
  logGroupName: logGroup.logGroupName,
  logStreamName: "audit",
});
const putLogEvents = yield* AWS.Logs.PutLogEvents(logGroup);

// runtime
yield* putLogEvents({
  logStreamName: "audit",
  logEvents: [{ timestamp, message: "user.login id=123" }],
});

Consuming Log Events

// Subscribe a Lambda handler to matching events (creates the
// subscription filter + invoke permission automatically).
yield* AWS.Logs.consumeLogEvents(
  logGroup,
  { filterPattern: "?ERROR ?Error" },
  (events) =>
    Stream.runForEach(events, (event) =>
      Effect.log(`${event.logStream}: ${event.message}`),
    ),
);

Metrics

yield* AWS.Logs.MetricFilter("ErrorCount", {
  logGroupName: logGroup.logGroupName,
  filterPattern: '"ERROR"',
  metricTransformations: [{
    metricName: "ErrorCount",
    metricNamespace: "MyApp",
    metricValue: "1",
  }],
});