cdk-log-notifier: Filter CloudWatch logs and post to Slack.

The AWS CDK Construct to build a system that gather CloudWatch logs, filter and post to Slack.

Example Usage

Watch the all logs contains "ERROR" from Lambda functions.

const logNotifier = new LogNotifier(this, 'logNotifier', {
  filterPattern: logs.FilterPattern.allTerms('ERROR'),
  slackIncomingWebhookUrl: 'https://hooks.slack.com/...', // Use yours.
});

logNotifier.watch(lambdaFunc1.logGroup);
logNotifier.watch(lambdaFunc2.logGroup);

Installation

npm i @thedesignium/cdk-log-notifier

API Reference

Class: LogNotifier

new LogNotifier(scope: cdk.Construct, id: string, props: LogNotifierProps)

The properties in props:

• filterPattern: The FilterPattern object in aws-cloudwatch module. The logs is filtered as specified here. Required.

• slackIncomingWebhookUrl: The Incoming Webhook URL of Slack. Create for the Slack channel the logs should be posted. Required.

• dateTimeFormatOptions: The arguments of the DateTimeFormat constructor, used to format the datetime which shown at the bottom of the Slack message. If omitted, it's formatted like 12/20, 3:00:00 AM UTC. Optional.

  Example:

    dateTimeFormatOptions: {
      locales: 'ja-JP',
      timeZone: 'Asia/Tokyo',
      month: 'numeric',
      day: 'numeric',
      hour: 'numeric',
      minute: 'numeric',
      second: 'numeric',
    }

Static Method: fromAttributes

LogNotifier.fromAttributes(scope: cdk.Construct, id: string, attrs: LogNotifierAttributes): LogNotifier

Instantiate from the attributes. Put the value of logNotifier.attributes as attrs parameter.

Method: watch

logNotifier.watch(logGroup: logs.LogGroup): void

Add the log group to watch list to notify. The logs in the watched log groups are filtered by the filterPattern and posted to Slack.

Property: attributes

attributes: LogNotifierAttributes

To use with LogNotifier.fromAttributes().

Containing Resources

• logs.SubscriptionFilter
• lambda.Function

Limitation

The watch() method attaches a Subscription to the subject logGroup. The number of subscription can be attached to a logGroup, however, is only one. So it'll fail if the logGroup has another subscription already. Similary, the watched logGroup can't be attached another subscription nor watched from another LogNotifier.

Motivation

There were 2 requirements:

1. Notice the all logs produced by console.error()(not only the crash report such InvocationError)
2. Jump easily to CloudWatch via link

We tried Lambda's error metric + CloudWatch Alarm + Chatbot and CloudWatch Metrics Filter + CloudWatch Alarm + Chatbot, but the former system don't satisfy [1] and the latter system don't satisfy [2]. That's why we need this.

FAQ

Cross Stack?

Possible. Export all values in LogNotifier.prototype.attributes, import it and use LogNotifier.fromAttributes() in another Stack.

How can I customize the Slack bot icon or name?

You can set at Slack App setting page, or Incoming Webhook configuration page if you use Legacy Incoming Webhook.

No support for other languages than TypeScript?

I'm not familiar with jsii so I leave it for now. Contribution is welcome.