# HttpCodeTarget

Count of HTTP status originating from the targets.

- Source: [`aws-elasticloadbalancingv2/lib/alb/application-load-balancer.ts`](https://github.com/aws/aws-cdk/blob/v2.274.0/packages/aws-cdk-lib/aws-elasticloadbalancingv2/lib/alb/application-load-balancer.ts#L902)

## Example

```ts
import * as cloudwatch from 'aws-cdk-lib/aws-cloudwatch';

declare const service: ecs.FargateService;
declare const blueTargetGroup: elbv2.ApplicationTargetGroup;
declare const greenTargetGroup: elbv2.ApplicationTargetGroup;
declare const listener: elbv2.IApplicationListener;

// Alarm on the number of unhealthy ECS tasks in each target group
const blueUnhealthyHosts = new cloudwatch.Alarm(this, 'BlueUnhealthyHosts', {
  alarmName: Stack.of(this).stackName + '-Unhealthy-Hosts-Blue',
  metric: blueTargetGroup.metricUnhealthyHostCount(),
  threshold: 1,
  evaluationPeriods: 2,
});

const greenUnhealthyHosts = new cloudwatch.Alarm(this, 'GreenUnhealthyHosts', {
  alarmName: Stack.of(this).stackName + '-Unhealthy-Hosts-Green',
  metric: greenTargetGroup.metricUnhealthyHostCount(),
  threshold: 1,
  evaluationPeriods: 2,
});

// Alarm on the number of HTTP 5xx responses returned by each target group
const blueApiFailure = new cloudwatch.Alarm(this, 'Blue5xx', {
  alarmName: Stack.of(this).stackName + '-Http-5xx-Blue',
  metric: blueTargetGroup.metricHttpCodeTarget(
    elbv2.HttpCodeTarget.TARGET_5XX_COUNT,
    { period: Duration.minutes(1) },
  ),
  threshold: 1,
  evaluationPeriods: 1,
});

const greenApiFailure = new cloudwatch.Alarm(this, 'Green5xx', {
  alarmName: Stack.of(this).stackName + '-Http-5xx-Green',
  metric: greenTargetGroup.metricHttpCodeTarget(
    elbv2.HttpCodeTarget.TARGET_5XX_COUNT,
    { period: Duration.minutes(1) },
  ),
  threshold: 1,
  evaluationPeriods: 1,
});

new codedeploy.EcsDeploymentGroup(this, 'BlueGreenDG', {
  // CodeDeploy will monitor these alarms during a deployment and automatically roll back
  alarms: [blueUnhealthyHosts, greenUnhealthyHosts, blueApiFailure, greenApiFailure],
  autoRollback: {
    // CodeDeploy will automatically roll back if a deployment is stopped
    stoppedDeployment: true,
  },
  service,
  blueGreenDeploymentConfig: {
    blueTargetGroup,
    greenTargetGroup,
    listener,
  },
  deploymentConfig: codedeploy.EcsDeploymentConfig.CANARY_10PERCENT_5MINUTES,
});
```

## Members

| Member | Description |
| --- | --- |
| `TARGET_2XX_COUNT` | The number of 2xx response codes from targets. |
| `TARGET_3XX_COUNT` | The number of 3xx response codes from targets. |
| `TARGET_4XX_COUNT` | The number of 4xx response codes from targets. |
| `TARGET_5XX_COUNT` | The number of 5xx response codes from targets. |