Example: Count log events
The simplest type of log event monitoring is to count the number of log events that occur. You might want to do this to keep a count of all events, to create a "heartbeat" style monitor or just to practice creating metric filters.
In the following CLI example, a metric filter called MyAppAccessCount is applied to the log group MyApp/access.log to create the metric EventCount in the CloudWatch namespace MyNamespace. The filter is configured to match any log event content and to increment the metric by "1".
To create a metric filter using the CloudWatch console
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Open the CloudWatch console at https://console.amazonaws.cn/cloudwatch/
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In the navigation pane, choose Log groups.
Choose the name of a log group.
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Choose
Actions, Create metric filter. -
Leave Filter Pattern and Select Log Data to Test blank.
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Choose Next, and then for Filter Name, type
EventCount. -
Under Metric Details, for Metric Namespace, type
MyNameSpace. -
For Metric Name, type
MyAppEventCount. Confirm that Metric Value is 1. This specifies that the count is incremented by 1 for every log event.
For Default Value enter 0, and then choose Next. Specifying a default value ensures that data is reported even during periods when no log events occur, preventing spotty metrics where data sometimes does not exist.
Choose Create metric filter.
To create a metric filter using the Amazon CLI
At a command prompt, run the following command:
aws logs put-metric-filter \ --log-group-name MyApp/access.log \ --filter-name EventCount \ --filter-pattern " " \ --metric-transformations \ metricName=MyAppEventCount,metricNamespace=MyNamespace,metricValue=1,defaultValue=0
You can test this new policy by posting any event data. You should see data points published to the metric MyAppAccessEventCount.
To post event data using the Amazon CLI
At a command prompt, run the following command:
aws logs put-log-events \ --log-group-name MyApp/access.log --log-stream-name TestStream1 \ --log-events \ timestamp=1394793518000,message="Test event 1" \ timestamp=1394793518000,message="Test event 2" \ timestamp=1394793528000,message="This message also contains an Error"