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Building Scalable Web Applications Using AWS CLI & WordPress

Try Out Health Checks

Explore how to use AWS CLI commands to monitor the health of your WordPress instances behind a load balancer. Learn to check target health, simulate instance failure, and understand how auto-scaling and load balancing ensure your site’s resilience.

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Let’s see if our health checks work and how we can check them. We'll use the elbv2 describe-target-health command. We just need to pass the target group ARN via the --target-group-arn parameter. So, the command would look like this:

Shell
aws elbv2 describe-target-health --target-group-arn <target-group-arn>

To get the target group ARN, we can use the describe-target-groups command again, just like we did in our last lesson. The full command, therefore, looks like this:

Shell
aws elbv2 describe-target-health \
    --target-group-arn $(aws elbv2 describe-target-groups \
    --names wordpress-instances \
    --query 'TargetGroups[*].TargetGroupArn' \
    --output text)

Run the command in the terminal below:

Terminal 1
Terminal
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The output should be similar to this:

Javascript (babel-node)
{
    "TargetHealthDescriptions": [
        {
            "Target": {
                "Id": "i-0184ea1e52d5d5029",
                "Port": 80
            },
            "HealthCheckPort": "80",
            "TargetHealth": {
                "State": "healthy"
            }
        },
        {
            "Target": {
                "Id": "i-07ee1bd00625b312c",
                "Port": 80
            },
            "HealthCheckPort": "80",
            "TargetHealth": {
                "State": "healthy"
            }
        }
    ]
}

As we can see, both targets are healthy ( ...