Kubernetes Ephemeral Containers: Enhancing Security and Streamlining Troubleshooting in Production Clusters

Kubernetes ephemeral containers are a powerful feature designed to help operators debug and troubleshoot running Pods without disrupting primary workloads. These short-lived containers allow you to inspect file systems, network settings, or running processes in real time, then vanish without affecting the Pod’s primary containers. This capability is particularly useful for diagnosing issues that cannot be replicated in a separate environment.

In this article, we’ll explore the benefits of ephemeral containers, their use cases, and a step-by-step guide to using them effectively. We’ll also discuss how ZippyOPS, a trusted microservice consulting provider, can help you optimize your DevOps, DevSecOps, and Cloud operations.

What Are Ephemeral Containers?

Ephemeral containers are special containers added to an existing Pod for debugging purposes. Unlike regular containers, they do not run as part of the application workload. Instead, they share the same resources (network namespace, volumes, etc.) as the other containers in the Pod, making them ideal for real-time diagnosis. Once debugging is complete, the ephemeral container can be removed without needing to recreate the entire Pod.

Key Features of Ephemeral Containers:

• Short-lived: Designed exclusively for debugging or troubleshooting.

• Non-disruptive: Do not impact existing application containers in the Pod.

• Resource-sharing: Share resources like storage volumes and network namespaces with the Pod.

Security Considerations with Ephemeral Containers

Ephemeral containers enhance security by limiting prolonged access to production Pods. By enforcing strict Role-Based Access Control (RBAC) rules, you can ensure that only authorized users can add and run ephemeral containers. Since these containers are automatically removed after debugging, the attack surface is minimized, reinforcing overall cluster security.

Use Cases for Ephemeral Containers

1. Troubleshooting Application Crashes: Inspect logs or run debugging tools in a crashed or crashing container without altering the main container’s configuration.

2. Network Debugging: Install tools like tcpdump or netstat to diagnose network issues within the Pod’s network namespace.

3. Live File System Checks: Verify file corruption or incorrect file paths in real time.

Prerequisites for Using Ephemeral Containers

• Kubernetes Version: Ephemeral containers require Kubernetes 1.23 or later. For older versions, you may need to enable the EphemeralContainers feature gate.

• kubectl: Ensure your local kubectl client matches or exceeds your cluster’s control plane version.

• RBAC Permissions: You need permission to use the kubectl debug command and update Pods.

Step-by-Step Guide: Using Ephemeral Containers

1. Verify Your Cluster’s Configuration

Check your Kubernetes version to ensure compatibility:

kubectl version

Ensure the Server Version is at least 1.23. If you’re using a managed environment like EKS, AKS, or GKE, confirm the cluster version from your provider’s dashboard or CLI.

2. Identify the Pod You Want to Debug

List Pods in a specific namespace:

kubectl get pods -n 

Choose the Pod you need to troubleshoot, for example: my-app-pod-abc123.

3. Add an Ephemeral Container Using kubectl debug

Use the kubectl debug command to add an ephemeral container. For example, we’ll use a simple Ubuntu image:

kubectl debug my-app-pod-abc123 -n  \
--image=ubuntu \
--target=my-container \
--interactive=true \
--tty=true

Here’s a breakdown of the flags:

• my-app-pod-abc123: The name of the existing Pod.

• --image=ubuntu: Docker image to use for the ephemeral container.

• --target=my-container: (Optional) Specifies which container in the Pod to target for namespace sharing.

• --interactive=true and --tty=true: Allows you to get a shell session inside the ephemeral container.

Once executed, you’ll get a shell prompt in the ephemeral container. You can now run debugging commands like ls, ps, or netstat.

4. Confirm Ephemeral Container Creation

In another terminal, or after exiting the ephemeral container’s shell, run:

kubectl get pod my-app-pod-abc123 -n  -o yaml

You should see a new section under spec or status describing the ephemeral container.

5. Debug and Troubleshoot

From within the ephemeral container, you can:

• Check logs or app configuration.

• Use debugging tools like curl, wget, or telnet to verify network connectivity.

• Inspect environment variables to confirm your application’s configuration.

Example commands:

curl http://localhost:8080/health
env | grep MY_APP_
ps aux

6. Clean Up Ephemeral Containers

Ephemeral containers are removed automatically when the Pod is destroyed. To remove the ephemeral container without deleting the Pod, you can patch the Pod spec. However, ephemeral containers are not meant to be long-lived.

Best Practices for Using Ephemeral Containers

• Use Minimal Images: Choose lightweight images like busybox or distroless to reduce overhead.

• Restrict RBAC: Limit who can create ephemeral containers to minimize security risks.

• Log Debug Sessions: Keep track of ephemeral container usage for auditing and compliance.

• Avoid Dependency: Ephemeral containers are for debugging only. For permanent sidecar or helper containers, configure them in the Pod spec from the start.

Conclusion

Ephemeral containers are a versatile and powerful tool for troubleshooting issues in real time without impacting primary application containers. Whether you’re running Kubernetes on EKS, AKS, GKE, or on-prem, understanding and using ephemeral containers can significantly reduce your mean-time-to-recovery (MTTR) and improve operational efficiency.

At ZippyOPS, we specialize in helping organizations optimize their infrastructure and streamline operations. If you’re interested in exploring ephemeral containers or need expert guidance, explore our services, check out our products, or view our solutions. For a demo, visit our YouTube playlist.

If this seems interesting, please email us at [email protected] for a call. Let’s build scalable, efficient, and secure systems together!