OpenLambdaMonitoring.ts

/**
 * This class' sole purpose is to use LambdaFunctionMonitoring via composition rather than inheritance. The problem with the current design
 * of the library is that it tries to be one-size-fits-all and packs a lot of features into extendable template classes. The issue is that
 * these classes do not allow a decent level of customization. Extending them sometimes works, but can fail short in other cases.
 *
 * The solution? Ditch inheritance and use composition, allowing the user to do anything they want. Now, this class just becomes a thing that
 * knows about Lambda and its monitoring, but doesn't try to impose one template for monitoring, only ingredients for users to do so.
 * Thus, we just make all immutable properties public rather than protected.
 *
 * I opened a feature request on Github to get this pattern into the library directly: https://github.com/cdklabs/cdk-monitoring-constructs/issues/218
 */
export class OpenLambdaMonitoring extends LambdaFunctionMonitoring {
    public readonly title: string
    public readonly functionUrl?: string
    public readonly namingStrategy: MonitoringNamingStrategy
    public readonly metricFactory: LambdaFunctionMetricFactory
    public readonly alarmFactory: AlarmFactory
    public readonly errorAlarmFactory: ErrorAlarmFactory
    public readonly latencyAlarmFactory: LatencyAlarmFactory
    public readonly tpsAlarmFactory: TpsAlarmFactory
    public readonly taskHealthAlarmFactory: TaskHealthAlarmFactory
    public readonly ageAlarmFactory: AgeAlarmFactory
    public readonly usageAlarmFactory: UsageAlarmFactory
    public readonly latencyAnnotations: HorizontalAnnotation[]
    public readonly errorCountAnnotations: HorizontalAnnotation[]
    public readonly errorRateAnnotations: HorizontalAnnotation[]
    public readonly invocationCountAnnotations: HorizontalAnnotation[]
    public readonly invocationRateAnnotations: HorizontalAnnotation[]
    public readonly tpsAnnotations: HorizontalAnnotation[]
    public readonly cpuTotalTimeAnnotations: HorizontalAnnotation[]
    public readonly memoryUsageAnnotations: HorizontalAnnotation[]
    public readonly maxIteratorAgeAnnotations: HorizontalAnnotation[]
    public readonly tpsMetric: MetricWithAlarmSupport
    public readonly p50LatencyMetric: MetricWithAlarmSupport
    public readonly p90LatencyMetric: MetricWithAlarmSupport
    public readonly p99LatencyMetric: MetricWithAlarmSupport
    public readonly faultCountMetric: MetricWithAlarmSupport
    public readonly faultRateMetric: MetricWithAlarmSupport
    public readonly invocationCountMetric: MetricWithAlarmSupport
    public readonly throttlesCountMetric: MetricWithAlarmSupport
    public readonly throttlesRateMetric: MetricWithAlarmSupport
    public readonly concurrentExecutionsCountMetric: MetricWithAlarmSupport
    public readonly provisionedConcurrencySpilloverInvocationsCountMetric: MetricWithAlarmSupport
    public readonly provisionedConcurrencySpilloverInvocationsRateMetric: MetricWithAlarmSupport
    public readonly maxIteratorAgeMetric: MetricWithAlarmSupport
    public readonly lambdaInsightsEnabled: boolean
    public readonly enhancedMetricFactory?: LambdaFunctionEnhancedMetricFactory
    public readonly enhancedMonitoringMaxCpuTotalTimeMetric?: MetricWithAlarmSupport
    public readonly enhancedMonitoringP90CpuTotalTimeMetric?: MetricWithAlarmSupport
    public readonly enhancedMonitoringAvgCpuTotalTimeMetric?: MetricWithAlarmSupport
    public readonly enhancedMonitoringMaxMemoryUtilizationMetric?: MetricWithAlarmSupport
    public readonly enhancedMonitoringP90MemoryUtilizationMetric?: MetricWithAlarmSupport
    public readonly enhancedMonitoringAvgMemoryUtilizationMetric?: MetricWithAlarmSupport
    public readonly enhancedMetricFunctionCostMetric?: MetricWithAlarmSupport

    public createTitleWidget(): MonitoringHeaderWidget {
        return super.createTitleWidget()
    }

    public createTpsWidget(width: number, height: number): GraphWidget {
        return super.createTpsWidget(width, height)
    }

    public createLatencyWidget(width: number, height: number): GraphWidget {
        return super.createLatencyWidget(width, height)
    }

    public createErrorCountWidget(width: number, height: number): GraphWidget {
        return super.createErrorCountWidget(width, height)
    }

    public createErrorRateWidget(width: number, height: number): GraphWidget {
        return super.createErrorRateWidget(width, height)
    }

    public createRateWidget(width: number, height: number): GraphWidget {
        return super.createRateWidget(width, height)
    }

    public createInvocationWidget(width: number, height: number): GraphWidget {
        return super.createInvocationWidget(width, height)
    }

    public createIteratorAgeWidget(width: number, height: number): GraphWidget {
        return super.createIteratorAgeWidget(width, height)
    }

    public createLambdaInsightsCpuWidget(width: number, height: number): GraphWidget {
        return super.createLambdaInsightsCpuWidget(width, height)
    }

    public createLambdaInsightsMemoryWidget(width: number, height: number): GraphWidget {
        return super.createLambdaInsightsMemoryWidget(width, height)
    }

    public createLambdaInsightsFunctionCostWidget(width: number, height: number): GraphWidget {
        return super.createLambdaInsightsFunctionCostWidget(width, height)
    }

    constructor(monitoring: AmazonMonitoringFacade, props: LambdaFunctionMonitoringProps) {
        super(monitoring, props)
    }
}

This gist is in relation to this issue: cdklabs/cdk-monitoring-constructs#218. The class thus created was used to implement highly customized monitoring for one single lambda in the application, with special properties (triggered by a single source at a known frequency):

public monitorSnapshotGenerationFunction(fn: SecureFunction) {
    const period = SNAPSHOT_POLLING_RATE;
    const lambdaMonitoring = new OpenLambdaMonitoring(this.monitoring, this.serviceHealthAlarmCollector, {
        lambdaFunction: fn,
        addFaultCountAlarm: {
            '': {maxErrorCount: 0 /* exclusive */, evaluationPeriods: 3, datapointsToAlarm: 3, period}
        }
    })

    this.monitoring.addSegment(new class {
        widgets() {
            return [
                lambdaMonitoring.createTitleWidget(),
                lambdaMonitoring.createErrorCountWidget(DEFAULT_WIDGET_WIDTH, DEFAULT_WIDGET_HEIGHT),
                createNewSnapshotGeneratedWidget(period), // custom business metric
            ]
        }

        alarmWidgets() {return []}
        summaryWidgets() {return []}
    })
}