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feat: alarms
1 parent 4c2fd17 commit 9e16206

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Lines changed: 312 additions & 0 deletions

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‎packages/cdk/bin/PfPApiApp.ts‎

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@@ -30,6 +30,7 @@ function main() {
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tc007NhsNumberValue: getConfigFromEnvVar("tc007NhsNumberValue", CDK_ENV_PREFIX, "not_in_use"),
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tc008NhsNumberValue: getConfigFromEnvVar("tc008NhsNumberValue", CDK_ENV_PREFIX, "not_in_use"),
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tc009NhsNumberValue: getConfigFromEnvVar("tc009NhsNumberValue", CDK_ENV_PREFIX, "not_in_use"),
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enableAlerts: getBooleanConfigFromEnvVar("enableAlerts", CDK_ENV_PREFIX, "true"),
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mutualTlsTrustStoreKey: props.isPullRequest ? undefined : getConfigFromEnvVar("trustStoreFile"),
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// CSOC API GW log destination - do not change
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csocApiGatewayDestination: "arn:aws:logs:eu-west-2:693466633220:destination:api_gateway_log_destination",

‎packages/cdk/constructs/MetricAlarm.ts‎

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import {Duration} from "aws-cdk-lib"
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import {Construct} from "constructs"
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import {
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Alarm,
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ComparisonOperator,
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Metric,
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TreatMissingData,
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Unit
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} from "aws-cdk-lib/aws-cloudwatch"
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import {ITopic} from "aws-cdk-lib/aws-sns"
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type AlarmDefinition = {
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name: string
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metric: string
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description: string
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dimensions?: {[key: string]: string}
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threshold?: number
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comparisonOperator?: ComparisonOperator
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unit?: Unit
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}
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export interface MetricAlarmProps {
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readonly stackName: string
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readonly enableAlerts: boolean
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readonly namespace: string
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readonly alarmDefinition: AlarmDefinition
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readonly slackAlertTopic: ITopic
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}
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export class MetricAlarm extends Construct {
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alarms: {[key: string]: Alarm}
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public constructor(scope: Construct, id: string, props: MetricAlarmProps){
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super(scope, id)
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const metricFunction = (metricName: string) =>
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new Metric({
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namespace: props.namespace,
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metricName,
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dimensionsMap: props.alarmDefinition.dimensions,
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unit: props.alarmDefinition.unit ?? Unit.COUNT,
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statistic: "Sum",
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period: Duration.minutes(1)
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})
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const alarm = new Alarm(this, `${props.alarmDefinition.name}Alarm`, {
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alarmName: `${props.stackName}-${props.alarmDefinition.name}`,
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metric: metricFunction(props.alarmDefinition.metric),
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threshold: props.alarmDefinition.threshold ?? 1,
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evaluationPeriods: 1,
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comparisonOperator:
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props.alarmDefinition.comparisonOperator ?? ComparisonOperator.GREATER_THAN_OR_EQUAL_TO_THRESHOLD,
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treatMissingData: TreatMissingData.NOT_BREACHING,
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alarmDescription: props.alarmDefinition.description,
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actionsEnabled: props.enableAlerts
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})
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alarm.addAlarmAction({
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bind: () => ({alarmActionArn: props.slackAlertTopic.topicArn})
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})
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alarm.addOkAction({
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bind: () => ({alarmActionArn: props.slackAlertTopic.topicArn})
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})
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alarm.addInsufficientDataAction({
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bind: () => ({alarmActionArn: props.slackAlertTopic.topicArn})
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})
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this.alarms = {[props.alarmDefinition.name]: alarm}
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}
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}

‎packages/cdk/resources/Alarms.ts‎

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@@ -0,0 +1,144 @@
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import {Fn} from "aws-cdk-lib"
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import {Unit} from "aws-cdk-lib/aws-cloudwatch"
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import {
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MetricFilter,
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FilterPattern,
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IFilterPattern,
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ILogGroup
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} from "aws-cdk-lib/aws-logs"
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import {Topic} from "aws-cdk-lib/aws-sns"
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import {TypescriptLambdaFunction} from "@nhsdigital/eps-cdk-constructs"
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import {Construct} from "constructs"
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import {MetricAlarm} from "../constructs/MetricAlarm"
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export interface AlarmsProps {
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readonly stackName: string
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readonly enableAlerts: boolean
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readonly functions: {[key: string]: TypescriptLambdaFunction}
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}
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export class Alarms extends Construct {
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public constructor(scope: Construct, id: string, props: AlarmsProps) {
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super(scope, id)
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const createMetricFilter = (
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metricFilterId: string,
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metricFilterProps: {
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filterName: string
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filterPattern: IFilterPattern
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logGroup: ILogGroup
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metricNamespace: string
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metricName?: string
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metricValue?: string
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unit?: Unit
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dimensions?: {[key: string]: string}
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}
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) => new MetricFilter(this, metricFilterId, {
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...metricFilterProps,
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metricName: metricFilterProps.metricName ?? "ErrorCount",
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metricValue: metricFilterProps.metricValue ?? "1",
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unit: metricFilterProps.unit ?? Unit.COUNT
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})
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const slackAlertTopic = Topic.fromTopicArn(
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this,
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"SlackAlertsTopic",
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Fn.importValue("lambda-resources:SlackAlertsSnsTopicArn")
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)
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const getMyPrescriptionsFunction = props.functions.getMyPrescriptions.function
50+
const enrichPrescriptionsFunction = props.functions.enrichPrescriptions.function
51+
52+
createMetricFilter("ServiceSearchErrorsLogsMetricFilter", {
53+
filterName: "ServiceSearchErrors",
54+
filterPattern: FilterPattern.literal(
55+
`{ ($.level = "ERROR") && ($.function_name = "${getMyPrescriptionsFunction.functionName}") ` +
56+
"&& $.message = %error in request to serviceSearch% }"
57+
),
58+
logGroup: getMyPrescriptionsFunction.logGroup,
59+
metricNamespace: "LambdaLogFilterMetrics",
60+
metricName: "ServiceSearchErrorCount",
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dimensions: {
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FunctionName: "$.function_name"
63+
}
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})
65+
66+
new MetricAlarm(this, "ServiceSearchErrors", {
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stackName: props.stackName,
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enableAlerts: props.enableAlerts,
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namespace: "LambdaLogFilterMetrics",
70+
alarmDefinition: {
71+
name: "ServiceSearch_Errors",
72+
metric: "ServiceSearchErrorCount",
73+
description: "Count of Service Search errors",
74+
dimensions: {
75+
FunctionName: getMyPrescriptionsFunction.functionName
76+
}
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},
78+
slackAlertTopic
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})
80+
81+
new MetricAlarm(this, "ServiceSearchUnhandledErrors", {
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stackName: props.stackName,
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enableAlerts: props.enableAlerts,
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namespace: "Lambda",
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alarmDefinition: {
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name: "ServiceSearch_UnhandledErrors",
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metric: "Errors",
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description: "Count of Service Search unhandled errors",
89+
dimensions: {
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FunctionName: getMyPrescriptionsFunction.functionName
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}
92+
},
93+
slackAlertTopic
94+
})
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createMetricFilter("GetMyPrescriptionsErrorsLogsMetricFilter", {
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filterName: `${props.stackName}_GetMyPrescriptionsErrors`,
98+
filterPattern: FilterPattern.literal(
99+
`{ ($.level = "ERROR") && ($.function_name = "${getMyPrescriptionsFunction.functionName}") ` +
100+
"&& ($.message != %error in request to serviceSearch%) }"
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),
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logGroup: getMyPrescriptionsFunction.logGroup,
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metricNamespace: "LambdaLogFilterMetrics",
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dimensions: {
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FunctionName: "$.function_name"
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}
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})
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109+
new MetricAlarm(this, "GetMyPrescriptionsErrors", {
110+
stackName: props.stackName,
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enableAlerts: props.enableAlerts,
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namespace: "LambdaLogFilterMetrics",
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alarmDefinition: {
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name: "GetMyPrescriptions_Errors",
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metric: "ErrorCount",
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description: "Count of GetMyPrescriptions errors",
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dimensions: {
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FunctionName: getMyPrescriptionsFunction.functionName
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}
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},
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slackAlertTopic
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})
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124+
createMetricFilter("EnrichPrescriptionsErrorsLogsMetricFilter", {
125+
filterName: `${props.stackName}_EnrichPrescriptionsErrors`,
126+
filterPattern: FilterPattern.literal("ERROR"),
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logGroup: enrichPrescriptionsFunction.logGroup,
128+
metricNamespace: "LambdaLogFilterMetrics",
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metricName: `${props.stackName}EnrichPrescriptionsErrorCount`
130+
})
131+
132+
new MetricAlarm(this, "EnrichPrescriptionsErrors", {
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stackName: props.stackName,
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enableAlerts: props.enableAlerts,
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namespace: "LambdaLogFilterMetrics",
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alarmDefinition: {
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name: "EnrichPrescriptions_Errors",
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metric: `${props.stackName}EnrichPrescriptionsErrorCount`,
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description: "Count of EnrichPrescriptions errors"
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},
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slackAlertTopic
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})
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}
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}

‎packages/cdk/stacks/PfPApiStack.ts‎

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@@ -3,6 +3,7 @@ import {nagSuppressions} from "../nagSuppressions"
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import {Functions} from "../resources/Functions"
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import {StateMachines} from "../resources/StateMachines"
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import {Apis} from "../resources/Apis"
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import {Alarms} from "../resources/Alarms"
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import {StandardStackProps} from "@nhsdigital/eps-cdk-constructs"
78
import Parameters from "../resources/Parameters"
89

@@ -19,6 +20,7 @@ export interface PfPApiStackProps extends StandardStackProps {
1920
readonly tc008NhsNumberValue: string
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readonly tc009NhsNumberValue: string
2122
readonly mutualTlsTrustStoreKey: string | undefined
23+
readonly enableAlerts: boolean
2224
readonly csocApiGatewayDestination: string
2325
readonly forwardCsocLogs: boolean
2426
}
@@ -56,6 +58,12 @@ export class PfPApiStack extends Stack {
5658
functions: functions.functions
5759
})
5860

61+
new Alarms(this, "Alarms", {
62+
stackName: props.stackName,
63+
enableAlerts: props.enableAlerts,
64+
functions: functions.functions
65+
})
66+
5967
new Apis(this, "Apis", {
6068
stackName: props.stackName,
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logRetentionInDays: props.logRetentionInDays,

‎packages/cdk/tests/MetricAlarm.test.ts‎

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@@ -0,0 +1,88 @@
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import {App, Stack} from "aws-cdk-lib"
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import {Template} from "aws-cdk-lib/assertions"
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import {ComparisonOperator, Unit} from "aws-cdk-lib/aws-cloudwatch"
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import {Topic} from "aws-cdk-lib/aws-sns"
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import {describe, expect, it} from "vitest"
6+
import {MetricAlarm} from "../constructs/MetricAlarm"
7+
8+
describe("MetricAlarm construct", () => {
9+
it("applies sane defaults for simple alarm definitions", () => {
10+
const app = new App()
11+
const stack = new Stack(app, "TestStack")
12+
const slackAlertTopic = new Topic(stack, "SlackAlertsTopic")
13+
14+
new MetricAlarm(stack, "SimpleMetricAlarm", {
15+
stackName: "pfp-test-stack",
16+
enableAlerts: true,
17+
namespace: "LambdaLogFilterMetrics",
18+
alarmDefinition: {
19+
name: "MySimpleAlarm",
20+
metric: "ErrorCount",
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description: "Simple alarm"
22+
},
23+
slackAlertTopic
24+
})
25+
26+
const template = Template.fromStack(stack)
27+
28+
template.hasResourceProperties("AWS::CloudWatch::Alarm", {
29+
AlarmName: "pfp-test-stack-MySimpleAlarm",
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Namespace: "LambdaLogFilterMetrics",
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MetricName: "ErrorCount",
32+
Threshold: 1,
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ComparisonOperator: "GreaterThanOrEqualToThreshold",
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Unit: "Count",
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Statistic: "Sum",
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Period: 60,
37+
EvaluationPeriods: 1,
38+
TreatMissingData: "notBreaching",
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AlarmDescription: "Simple alarm",
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ActionsEnabled: true
41+
})
42+
})
43+
44+
it("allows overriding threshold, comparison operator, unit and dimensions", () => {
45+
const app = new App()
46+
const stack = new Stack(app, "OverrideStack")
47+
const slackAlertTopic = new Topic(stack, "SlackAlertsTopic")
48+
49+
const metricAlarm = new MetricAlarm(stack, "OverrideMetricAlarm", {
50+
stackName: "pfp-test-stack",
51+
enableAlerts: false,
52+
namespace: "CustomNamespace",
53+
alarmDefinition: {
54+
name: "MyOverrideAlarm",
55+
metric: "Latency",
56+
description: "Override alarm",
57+
dimensions: {
58+
FunctionName: "my-function"
59+
},
60+
threshold: 250,
61+
comparisonOperator: ComparisonOperator.GREATER_THAN_THRESHOLD,
62+
unit: Unit.MILLISECONDS
63+
},
64+
slackAlertTopic
65+
})
66+
67+
expect(metricAlarm.alarms.MyOverrideAlarm).toBeDefined()
68+
69+
const template = Template.fromStack(stack)
70+
71+
template.hasResourceProperties("AWS::CloudWatch::Alarm", {
72+
AlarmName: "pfp-test-stack-MyOverrideAlarm",
73+
Namespace: "CustomNamespace",
74+
MetricName: "Latency",
75+
Threshold: 250,
76+
ComparisonOperator: "GreaterThanThreshold",
77+
Unit: "Milliseconds",
78+
Dimensions: [
79+
{
80+
Name: "FunctionName",
81+
Value: "my-function"
82+
}
83+
],
84+
AlarmDescription: "Override alarm",
85+
ActionsEnabled: false
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})
87+
})
88+
})

‎packages/cdk/tests/synth.test.ts‎

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@@ -53,6 +53,7 @@ describe("CDK synth smoke tests", () => {
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CDK_CONFIG_tc007NhsNumberValue: "9000000009",
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CDK_CONFIG_tc008NhsNumberValue: "9000000017",
5555
CDK_CONFIG_tc009NhsNumberValue: "9000000025",
56+
CDK_CONFIG_enableAlerts: "true",
5657
CDK_CONFIG_forwardCsocLogs: "false"
5758
}
5859
})

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