Create a Log Alarm on error patterns

You can create a Log Alarm that monitors your logs for error patterns and sends a notification when the error count exceeds a threshold.

The following example creates a Log Alarm that transitions to ALARM state when more than 10 ERROR messages appear in 3 out of 5 query executions.

aws cloudwatch put-log-alarm \
    --alarm-name "LambdaErrors" \
    --alarm-description "Alarm when Lambda error count exceeds 10" \
    --comparison-operator GreaterThanThreshold \
    --threshold 10 \
    --query-results-to-evaluate 5 \
    --query-results-to-alarm 3 \
    --treat-missing-data notBreaching \
    --alarm-actions "arn:aws:sns:region:account-id:topic-name" \
    --scheduled-query-configuration '{
        "QueryString": "fields @timestamp, @message | filter @message like /ERROR/",
        "LogGroupIdentifiers": ["/aws/lambda/my-function"],
        "ScheduledQueryRoleARN": "arn:aws:iam::account-id:role/ScheduledQueryRole",
        "AggregationExpression": "count(*)",
        "ScheduleConfiguration": {
            "ScheduleExpression": "rate(5 minutes)",
            "StartTimeOffset": 300
        }
    }'