OpenUnison Console Hangs: Fixing Pod Exec And Orchestra Issues

by Alex Johnson 63 views

Are you experiencing issues with your OpenUnison console hanging after opening multiple pod exec terminals, and are you also seeing your orchestra pod failing its liveness probe? This is a common problem that can be quite frustrating. Let's dive into the details of the bug, how to reproduce it, what's happening, and, most importantly, how to fix it. This guide will cover the root cause, steps to replicate the problem, the behavior you might observe, and, finally, a practical solution to get your console back up and running smoothly. We'll also consider the environment where these issues are most likely to appear and the orchestra deployment configuration that can influence the problem. Finally, we'll suggest a potential hypothesis based on observations.

Understanding the Problem: The Console Hang and Orchestra Failure

The primary issue revolves around the OpenUnison console becoming unresponsive when you open multiple pod terminal sessions (using exec) in different browser tabs. This leads to the console failing to load other Kubernetes resources. After the console hangs for a while, the orchestra pod, a critical component of OpenUnison, starts failing its liveness probe, eventually leading to restarts. This creates a cycle of instability, disrupting your access to the console and your ability to manage your Kubernetes resources. The problem seems to be directly linked to how the console handles WebSocket connections created by the pod exec sessions. When these connections are not properly managed, they can lead to resource exhaustion and, consequently, the observed failures. We'll explore the environment, Kubernetes versions, and deployment configurations to provide a comprehensive understanding of the issue. This is crucial for correctly identifying and resolving the problem. Let's delve deeper into how this issue manifests and how you can address it effectively.

The Ripple Effect: From Console Freeze to Pod Restart

When the console freezes, it's not just a minor inconvenience; it's a symptom of a deeper issue that affects the overall health of your OpenUnison deployment. The UI freeze is a consequence of the backend becoming saturated by the persistent WebSocket connections. This backend saturation leads to the crucial orchestra pod failing its liveness probe. This probe is designed to check the health of the pod and ensure it's functioning correctly. When the probe fails, Kubernetes recognizes the pod as unhealthy and attempts to restart it. While a restart might seem like a temporary fix, it's a reactive solution that doesn't address the underlying problem. The cycle of the console freeze, the orchestra pod failing its liveness probe, and the subsequent restart can severely impact your operational efficiency. It can disrupt workflows and cause delays. Therefore, it is important to address the root cause of these issues instead of relying on temporary fixes. This comprehensive guide will help you understand the problem thoroughly, enabling you to implement effective solutions. By addressing the root cause, you can ensure a stable and reliable OpenUnison console.

How to Recreate the Issue: Step-by-Step Guide

To fully understand the problem, you need to know how to reproduce it. Here is a detailed guide on how to replicate the issue of the console hanging and the orchestra pod failing its liveness probe. This will help you verify the fix. Make sure that you have an OpenUnison console set up and running, as this is the starting point. This section provides a step-by-step procedure to replicate the problem effectively and systematically. Following these steps can help you confirm the presence of the bug in your environment and aid in troubleshooting. Let's start the reproduction steps to ensure you can identify the problem.

Step-by-Step Reproduction Guide

Here’s a clear, concise guide to recreating the issue in your OpenUnison console:

  1. Log in to the OpenUnison console. Ensure you can access your console using your preferred method. Verify that the console is functioning correctly before starting the test.
  2. Open a pod and start a terminal (exec). Select any pod and initiate a terminal session using the exec command. Confirm that the terminal session opens and operates as expected. Keep this first terminal open.
  3. Open multiple exec terminals. Open approximately five browser tabs and start exec terminals in each tab. You can use the same pod or different pods. This is where the core of the problem lies – excessive simultaneous connections.
  4. Try to load Kubernetes resources. Attempt to load deployments, config maps, and other pods. Observe what happens when you try to navigate and interact with the console interface. Take note of any delays or failures to load resources.

By following these steps, you should be able to reproduce the console hang and witness the orchestra pod failing. Keep an eye on your Kubernetes dashboard for any signs of pod failures or restarts. Once you've reproduced the issue, you can try the provided solutions or experiment to discover the root cause.

What to Expect: Observing the Behavior

When you replicate the issue, you’ll observe a specific set of behaviors that indicate the problem. Understanding these behaviors is critical to diagnosing the root cause and verifying any solutions. Let's break down the common observations you will experience when encountering this bug. Knowing what to look for will help you identify the issue quickly and determine if your fix has worked.

Symptoms of the Issue

Here's what you'll typically see when the bug occurs:

  • Console UI Freeze: The console user interface becomes unresponsive. You will notice that the UI does not react to your clicks, and new resources don't load. The console appears frozen, with a loading indicator potentially spinning indefinitely.
  • Resource Loading Failure: When you attempt to load resources, such as deployments, config maps, or other pods, they will fail to load. The console may display an error message or simply remain in a loading state, without ever displaying the requested information.
  • Orchestra Pod Liveness Probe Failure: The orchestra pod will begin to fail its liveness probe. You can observe this in your Kubernetes dashboard or by using the kubectl get pods command. The pod's status will change to 0/1, indicating that the liveness probe is failing. The logs for the orchestra pod may provide additional details about the cause of the failure.
  • Orchestra Pod Restart: Eventually, Kubernetes will restart the orchestra pod due to repeated liveness probe failures. The pod will cycle through restarting, which will further disrupt the functionality of your OpenUnison console. You can see the pod being restarted in the Kubernetes dashboard or with the kubectl get events command.
  • Temporary Fix with Cache Clearing: Clearing the browser cache will temporarily resolve the issue. After clearing the cache, the console will become responsive again, and you will be able to load resources. However, the problem will return if you repeat the same actions of opening multiple terminal sessions.

Diving into the Details: Environment and Configuration

Understanding the environment and configuration where this issue occurs can provide important insights. Several factors can influence the frequency and severity of the console hang and orchestra pod failures. Knowing the specific environment details, such as the Kubernetes cluster type, version, OpenUnison components, browser, and ingress controller, allows us to analyze the issue effectively. The orchestra deployment configuration also plays a significant role in the problem, as it can affect resource allocation and management. Let's delve into the specific details to offer clarity.

The Environment Details

The environment in which this issue typically surfaces includes:

  • Kubernetes Clusters: The bug has been observed in both AKS (Azure Kubernetes Service) and EKS (Amazon Elastic Kubernetes Service) environments. This suggests that the issue is not specific to a particular cloud provider's Kubernetes implementation.
  • Kubernetes Version: The issue is present in Kubernetes version 1.33. Compatibility with this version is crucial for resolving the problem.
  • OpenUnison Components Version: The issue occurs with the latest versions of OpenUnison operator, orchestra, and portal-login components. Keeping these components up to date is crucial to ensure optimal functionality.
  • Kubernetes Dashboard Version: The Kubernetes dashboard version is also the latest. This dashboard is the tool used to monitor and manage Kubernetes resources. Its functionality is indirectly affected by this bug.
  • Browser: The bug is observed on both Chrome and Edge browsers, suggesting that the problem is not browser-specific. This means the issue is likely related to the underlying logic of how the OpenUnison console manages the WebSocket connections.
  • Ingress Controller: The Ingress Controller used is NGINX Ingress. The ingress controller manages external access to the services in a cluster, which may indirectly influence the connection handling. The interaction between the ingress controller and the WebSocket connections can be relevant.

Orchestra Deployment Configuration

The configuration of the orchestra pod is also important in understanding the issue. The configuration includes the number of replicas and the resource requests and limits per pod.

  • Replicas: The deployment uses two replicas. This setup provides some redundancy, but the simultaneous connection issue can still affect both replicas.
  • Resource Requests and Limits:
    • Requests: The orchestra pod requests 2 CPU and 2Gi of memory. These requests define the resources that Kubernetes guarantees the pod has available.
    • Limits: The pod is limited to 4 CPU and 8Gi of memory. The limits prevent the pod from using more resources than allocated. Limits prevent the pod from consuming excessive resources and potentially affecting the other pods in the cluster.

Observations and Hypothesis: Potential Cause

Based on these observations, the hypothesis is that the issue is related to WebSocket connections created by pod exec sessions remaining open or getting stuck. When multiple terminals are opened simultaneously, these connections are not being released correctly. This can lead to the exhaustion of resources, which causes the UI to freeze, the backend to saturate, and the liveness probe to fail, resulting in the restart of the orchestra pod. Clearing the browser cache removes or resets these stale WebSocket sessions, which temporarily resolves the issue. This suggests that the connections are not being properly closed or managed by the OpenUnison console, leading to a resource leak. Let’s dive deeper into these connections to understand how to fix the problem.

The Role of WebSocket Connections

WebSocket connections are used for real-time communication between the browser and the pod terminals. Each exec session creates a new WebSocket connection. If these connections are not properly closed when the terminal is closed or the browser tab is closed, they can remain open indefinitely. As the number of open connections increases, they can consume a lot of resources on the server side. As the number of open connections increases, they can consume a lot of resources. When the server’s resources are depleted, it leads to saturation, which slows down or stops other services, resulting in the observed console hang and liveness probe failures. Understanding how these WebSocket connections are managed is key to resolving the issue.

The Problem of Stale Connections

The stale connections issue results from connections not being properly terminated. Possible causes include issues with the console's code not closing connections on tab or session closure, network interruptions, or server-side problems that keep the connections open. These stale connections slowly but surely consume resources, leading to the console's degradation and the inevitable failure of the orchestra pod's liveness probe. These stale connections will trigger the failure in the liveness probe.

Troubleshooting and Possible Solutions

While the exact solution may depend on the specifics of the OpenUnison implementation, here are some general troubleshooting steps and possible solutions to address this issue.

Troubleshooting Steps

  1. Inspect Network Traffic: Use your browser's developer tools to inspect the network traffic when opening and closing pod exec terminals. Look for WebSocket connections and whether they are closed when the terminal is closed.
  2. Examine Server Logs: Check the OpenUnison server logs for any errors or warnings related to WebSocket connections or resource exhaustion. Look for clues that may indicate which parts of the code are causing problems.
  3. Monitor Resource Usage: Use Kubernetes monitoring tools (like Prometheus and Grafana) to monitor the resource usage of the orchestra pod and the overall cluster. Identify if there's any memory leaks or excessive CPU usage.
  4. Test with Different Browsers and Incognito Mode: Try reproducing the issue with different browsers and in incognito mode to rule out any browser-specific extensions or caching issues.

Possible Solutions

  1. Improve WebSocket Connection Management: The most crucial solution is to improve how WebSocket connections are managed. Ensure that connections are properly closed when the terminal is closed, the browser tab is closed, or the user logs out. This may involve adding code to explicitly close the WebSocket connections in the OpenUnison console.
  2. Implement Connection Timeouts: Implement connection timeouts to automatically close inactive WebSocket connections. This will prevent connections from remaining open indefinitely and consuming resources.
  3. Optimize Resource Allocation: Review and potentially increase the resource requests and limits for the orchestra pod to ensure it has enough resources to handle the load. Make sure the orchestra has enough CPU and memory to handle the load.
  4. Caching and Browser Optimization: Implement efficient caching strategies in the console to reduce the load on the server. Also, advise users to clear their browser cache periodically, or automatically clear the cache when the user closes the console, to remove any stale or broken connections.
  5. Review the NGINX Configuration: Check your NGINX ingress controller configuration to ensure it is correctly configured for WebSocket connections. The ingress controller must handle these connections correctly.
  6. Update OpenUnison: Ensure that you are running the latest version of OpenUnison, as updates may include fixes for connection management issues.

By following these steps and exploring these solutions, you should be able to resolve the console hang and orchestra pod failure issue. Remember to test thoroughly after making changes. Always make sure to test your changes.

Conclusion: Keeping Your OpenUnison Console Running Smoothly

Addressing the OpenUnison console hang and the orchestra pod failures requires a comprehensive approach. It starts with a detailed understanding of the issue, from reproducing the problem to observing its behavior and diagnosing the underlying causes. By thoroughly investigating the environment, configurations, and the role of WebSocket connections, you can pinpoint the root of the problem and implement effective solutions. Improving WebSocket connection management, setting up connection timeouts, and optimizing resource allocation are crucial steps. This guide has equipped you with the necessary knowledge and steps to resolve these challenges, ensuring that your OpenUnison console remains stable and responsive.

For additional information and support, consider checking out the official OpenUnison documentation: OpenUnison Documentation