Why probes keep applications healthy in Kubernetes - See It in Action

Why probes keep applications healthy

📖 Scenario: You are managing a Kubernetes cluster that runs a simple web application. To keep the application healthy and responsive, Kubernetes uses probes to check the application's status regularly.Probes help Kubernetes decide when to restart the application or stop sending traffic to it if it is not working properly.

🎯 Goal: Learn how to define and use Kubernetes probes (liveness and readiness) in a pod configuration to keep the application healthy.

📋 What You'll Learn

Create a basic pod configuration with a container running a simple web server

Add a liveness probe to check if the application is alive

Add a readiness probe to check if the application is ready to serve traffic

Print the final pod configuration YAML

💡 Why This Matters

🌍 Real World

Kubernetes probes help keep applications running smoothly by automatically detecting problems and restarting containers if needed.

💼 Career

Understanding probes is essential for DevOps engineers and site reliability engineers to maintain healthy and reliable applications in production.

1

Create a basic pod configuration

Create a variable called pod_config that holds a dictionary representing a Kubernetes pod configuration with these exact values: apiVersion set to v1, kind set to Pod, metadata with name set to myapp-pod, and spec with one container named myapp-container running the image nginx:1.21.

Kubernetes

# Create the pod_config dictionary with the specified keys and values
# Your code here

Need a hint?

Use nested dictionaries and lists to build the pod configuration.

2

Add a liveness probe

Add a livenessProbe to the container inside pod_config. The probe should use an httpGet action with path set to /healthz, port set to 80, and initialDelaySeconds set to 5.

Kubernetes

pod_config = {
    'apiVersion': 'v1',
    'kind': 'Pod',
    'metadata': {
        'name': 'myapp-pod'
    },
    'spec': {
        'containers': [
            {
                'name': 'myapp-container',
                'image': 'nginx:1.21'
                # Add livenessProbe here
            }
        ]
    }
}
# Your code here

Need a hint?

The livenessProbe is a dictionary inside the container dictionary.

3

Add a readiness probe

Add a readinessProbe to the container inside pod_config. The probe should use an httpGet action with path set to /ready, port set to 80, and initialDelaySeconds set to 3.

Kubernetes

pod_config = {
    'apiVersion': 'v1',
    'kind': 'Pod',
    'metadata': {
        'name': 'myapp-pod'
    },
    'spec': {
        'containers': [
            {
                'name': 'myapp-container',
                'image': 'nginx:1.21',
                'livenessProbe': {
                    'httpGet': {
                        'path': '/healthz',
                        'port': 80
                    },
                    'initialDelaySeconds': 5
                }
                # Add readinessProbe here
            }
        ]
    }
}
# Your code here

Need a hint?

The readinessProbe is similar to the livenessProbe but with different path and delay.

4

Print the final pod configuration

Write a print statement to display the pod_config dictionary.

Kubernetes

pod_config = {
    'apiVersion': 'v1',
    'kind': 'Pod',
    'metadata': {
        'name': 'myapp-pod'
    },
    'spec': {
        'containers': [
            {
                'name': 'myapp-container',
                'image': 'nginx:1.21',
                'livenessProbe': {
                    'httpGet': {
                        'path': '/healthz',
                        'port': 80
                    },
                    'initialDelaySeconds': 5
                },
                'readinessProbe': {
                    'httpGet': {
                        'path': '/ready',
                        'port': 80
                    },
                    'initialDelaySeconds': 3
                }
            }
        ]
    }
}
# Your code here

Need a hint?

Use print(pod_config) to display the dictionary.