How to add custom Metric and Alarm to AWS Lambda function via aws-cdk

Question

I kind of stuck with configuring cdk a common use case: to have an Alarm and Metric for Lambda Function

import lambda = require("@aws-cdk/aws-lambda")
import { Duration } from "@aws-cdk/core"
import lambda = require("@aws-cdk/aws-lambda")
import { Duration } from "@aws-cdk/core";
import { LogGroup } from '@aws-cdk/aws-logs'
import { MetricFilter, FilterPattern } from '@aws-cdk/aws-logs'
import { Alarm, ComparisonOperator, TreatMissingData } from "@aws-cdk/aws-cloudwatch"

const lambdaFn = new lambda.Function(this, "VouchersPayoutQueueConsumer", {
    functionName: 'lambda-custom-name',
    runtime: lambda.Runtime.NODEJS_10_X,
    code: lambda.Code.fromAsset("dir_name"),
    timeout: Duration.seconds(15),
    memorySize: 1024,
    handler: "handler.handlerMethod",
})

const METRIC_NAME = 'metric-name'
const METRIC_NAMESPACE = 'metric-namespace'

new MetricFilter(this, `MetricFilterId`, {
    metricName: METRIC_NAME,
    metricNamespace: METRIC_NAMESPACE,
    logGroup: LogGroup.fromLogGroupName(this, "LambdaLogGroupId", `/aws/lambda/${lambdaFn.functionName}`),
    filterPattern: FilterPattern.stringValue("$.params.name", "==", "ReportErrorsToS3"),
    metricValue: "$.params.value"
})

new Alarm(this, "AlarmId", {
    metric,
    evaluationPeriods: 1,
    actionsEnabled: true,
    alarmName: `alarms-s3errors`,
    alarmDescription: "Alarm ReportErrorsToS3",
    comparisonOperator: ComparisonOperator.GREATER_THAN_THRESHOLD,
    treatMissingData: TreatMissingData.IGNORE,
    period: Duration.hours(1),
    threshold: 1,
    statistic: "max"
})

Where to get the metric and how to map it with MetricFilter?
How to set properly logGroup for MetricFilter to solve the issue:

1/4 | 11:02:05 AM | CREATE_FAILED | AWS::Logs::MetricFilter | MetricFilter (MetricFilter8E0FEF2B) The specified log group does not exist. (Service: AWSLogs; Status Code: 400; Error Code: ResourceNotFoundException; Request ID: a1395551-5768-40c3-baaa-cbb133effe7b)

AWS CDK AWS 1.22.0

elbik elbik · Accepted Answer · 2020-01-24T13:42:30

The metric is declared separately but the metricName and namespace must be the same as used for MetricFilter
LogGroup also must be instantiated separately but with the logGroupName which is the same as, the lambda will create.
- The suggestive discussion - log group config for lambda function

Result:

import { Metric } from "@aws-cdk/aws-cloudwatch";
import lambda = require("@aws-cdk/aws-lambda")
import { Duration } from "@aws-cdk/core";
import { LogGroup } from '@aws-cdk/aws-logs'
import { MetricFilter, FilterPattern } from '@aws-cdk/aws-logs'
import { Alarm, ComparisonOperator, TreatMissingData } from "@aws-cdk/aws-cloudwatch"

const LAMBDA_CUSTOM_NAME = `lambda-custom-name`

let logGroup = new LogGroup(this, 'LogGroup', {
  logGroupName: `/aws/lambda/${LAMBDA_CUSTOM_NAME}`
})

const lambdaFn = new lambda.Function(this, "VouchersPayoutQueueConsumer", {
    functionName: LAMBDA_CUSTOM_NAME,
    runtime: lambda.Runtime.NODEJS_10_X,
    code: lambda.Code.fromAsset("dir_name"),
    timeout: Duration.seconds(15),
    memorySize: 1024,
    handler: "handler.handlerMethod",
});


const METRIC_NAME = 'metric-name'
const METRIC_NAMESPACE = 'metric-namespace'

const metric = new Metric({
    namespace: METRIC_NAMESPACE,
    metricName: METRIC_NAME
})

new MetricFilter(this, `MetricFilterId`, {
    metricName: METRIC_NAME,
    metricNamespace: METRIC_NAMESPACE,
    logGroup: logGroup,
    filterPattern: FilterPattern.stringValue("$.params.name", "==", "ReportErrorsToS3"),
    metricValue: "$.params.value"
})

new Alarm(this, "AlarmId", {
    metric,
    evaluationPeriods: 1,
    actionsEnabled: true,
    alarmName: `alarms-s3errors`,
    alarmDescription: "Alarm ReportErrorsToS3",
    comparisonOperator: ComparisonOperator.GREATER_THAN_THRESHOLD,
    treatMissingData: TreatMissingData.IGNORE,
    period: Duration.hours(1),
    threshold: 1,
    statistic: "max"
})

How to add custom Metric and Alarm to AWS Lambda function via aws-cdk

2 Answers