As we've seen before, Lambda functions save their log events to CloudWatch. This lets us to watch our application's status easily, and we do not have to maintain any logging infrastructure for that. This is already a cool feature.
If you've ever used a logging solution such as Kibana, you should be familiar with saving search patterns in it, so you can create graphs using the occurrence frequency of a pattern in your logs. This is possible to have some functionality very easily in CloudWatch logs. This feature is called Create Metric Filter and automatically tests custom patterns against log lines and pushes them as a metric to CloudWatch. With that, for example, you can see how many times your log contained an ERROR string, you can monitor it via CloudWatch graphics, or you can even create alarms and take action...