Improve documentation and validation

cdklabs · Oct 20, 2023 · 8983536 · 8983536
1 parent dbce9aa
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Showing 2 changed files with 11 additions and 2 deletions.
diff --git a/lib/monitoring/aws-elasticache/ElastiCacheClusterMetricFactory.ts b/lib/monitoring/aws-elasticache/ElastiCacheClusterMetricFactory.ts
@@ -115,6 +115,9 @@ export class ElastiCacheClusterMetricFactory {
   /**
    * @see https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/CacheMetrics.Redis.html
    * Because Redis is single-threaded, you can use this metric to analyze the load of the Redis process itself.
+   * Note that you may want to monitor both Engine CPU Utilization as well as CPU Utilization as background
+   * processes can take up a significant portion of the CPU workload. This is especially important for 
+   * hosts with 2 vCPUs or less
    */
   metricMaxRedisEngineCpuUtilizationInPercent() {
     return this.metricFactory.createMetric(

diff --git a/lib/monitoring/aws-elasticache/ElastiCacheClusterMonitoring.ts b/lib/monitoring/aws-elasticache/ElastiCacheClusterMonitoring.ts
@@ -44,12 +44,14 @@ export interface ElastiCacheClusterMonitoringOptions
   readonly clusterType: ElastiCacheClusterType;
 
   /**
-   * Add CPU usage alarm
+   * Add CPU usage alarm (useful for all clusterTypes including Redis)
    */
   readonly addCpuUsageAlarm?: Record<string, UsageThreshold>;
 
   /**
    * Add redis engine CPU usage alarm
+   * Note: it is recommended to monitor CPU Utilization as well
+   * for hosts with two vCPUs or less
    */
   readonly addRedisEngineCpuUsageAlarm?: Record<string, UsageThreshold>;
 
@@ -114,7 +116,7 @@ export class ElastiCacheClusterMonitoring extends Monitoring {
   ) {
     super(scope, props);
 
-    this.elastiCacheClusterType = props.clusterType;
+    this.clusterType = props.clusterType;
 
     const clusterType = capitalizeFirstLetterOnly(
       ElastiCacheClusterType[props.clusterType]
@@ -173,6 +175,10 @@ export class ElastiCacheClusterMonitoring extends Monitoring {
       this.addAlarm(createdAlarm);
     }
 
+    if (props.addRedisEngineCpuUsageAlarm !== undefined && props.clusterType !== ElastiCacheClusterType.REDIS) {
+      throw new Error("It is only possible to alarm on Redis Engine CPU Usage for Redis clusters")
+    }
+
     for (const disambiguator in props.addRedisEngineCpuUsageAlarm) {
       const alarmProps = props.addRedisEngineCpuUsageAlarm[disambiguator];
       const createdAlarm = this.usageAlarmFactory.addMaxCpuUsagePercentAlarm(