Fix: Workspace Stops Before Template Version Change?

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Hey everyone! Let's dive into a tricky regression issue where our workspace wasn't stopping before a template version change, especially when dynamic parameters were enabled. This could lead to some serious resource conflicts, so let's break down what happened, why it happened, and how we're fixing it.

The Problem: Workspaces Not Stopping

So, the main issue here is that under certain conditions, our workspaces weren't stopping before we tried to update their template versions. Think of it like trying to renovate a house while people are still living there – things can get messy!

Specifically, we noticed this happening in a couple of scenarios:

  1. Dynamic Parameters Enabled: When we had dynamic parameters turned on, the workspace would just start with the new version without stopping the old one first. Oops!
  2. Explicit Version Change: If a user went in and explicitly changed the template version, the same thing would happen – no stopping, just straight into the new version.

To really understand the impact, consider this: without stopping the workspace, we risk resource conflicts. Imagine two versions of the same workspace fighting over the same resources – not a pretty picture. This is why ensuring a clean stop before starting a new version is crucial.

Current vs. Expected Behavior

Let's clarify what should be happening versus what was happening. Previously, when a user changed the template version of their workspace, we saw inconsistent behavior depending on the circumstances. Here’s a breakdown:

  • With dynamic parameters disabled: Everything worked as expected. The workspace would stop first (if it was running), and then it would start with the new version. This is the correct behavior we want.
  • With dynamic parameters enabled: Here’s where things went wrong. The workspace would immediately start with the new version without stopping, potentially causing those nasty resource conflicts we talked about.
  • When explicitly changing versions via changeWorkspaceVersion: Another bug! The workspace would start immediately without stopping, regardless of whether dynamic parameters were enabled or not. This was a consistent failure point.

So, what’s the expected behavior? Simple:

  1. Check if the workspace is running: First, we need to know the current state of the workspace.
  2. Stop the workspace if running: If it’s running, we need to stop it and wait for it to complete its shutdown process. This is the critical step we were missing.
  3. Start the workspace with the new template version: Only after the workspace has stopped should we proceed with starting it with the new version.
  4. Handle cancellation appropriately: We also need to consider scenarios where the stop process is canceled midway. In such cases, we should bail out and not proceed with the version change.

This expected behavior ensures a smooth transition between template versions, preventing resource conflicts and maintaining the integrity of the workspace. Making sure these steps are followed is essential for a stable and reliable system.

Root Cause Analysis: Where Did We Go Wrong?

Okay, so we know what's happening and what should be happening, but why did this happen? Let's dig into the root cause. It turns out there are two main functions responsible for handling workspace updates, and they weren't playing nicely together.

We have:

updateWorkspace (api.ts:2303-2375)

This function is used when the template is updated, and the workspace needs the latest active version. Now, here's the kicker:

  • With dynamic params enabled: This is where the trouble started. The function would directly start the workspace without stopping it first (lines 2318-2338). This was a clear bypass of the stop-before-start logic.
  • With dynamic params disabled: In this case, the function actually worked correctly! It would stop the workspace before starting, as intended (lines 2358-2374).

changeWorkspaceVersion (api.ts:2254-2291)

This function is used when a user explicitly changes the template version. And guess what? It never stops the workspace before starting with the new version. Ouch!

  • Missing stop-first logic entirely: This function completely lacked the necessary code to stop the workspace, making it a prime suspect in our bug investigation.

So, the issue boils down to these two functions handling workspace updates differently. updateWorkspace had a conditional bypass for dynamic parameters, and changeWorkspaceVersion was missing the stop logic altogether. To resolve this, we need to ensure both functions follow the same consistent pattern.

Code Locations: Hunting Down the Culprits

To fix this, we needed to pinpoint the exact locations in the code where these issues were occurring. Think of it as a detective searching for clues at a crime scene. Here’s where we found the critical pieces of the puzzle:

  • site/src/api/api.ts:
    • changeWorkspaceVersion (line 2254-2291): This is where the missing stop logic resides. We need to add the stop-before-start mechanism here.
    • updateWorkspace (line 2303-2375): Specifically, the dynamic params path within this function is where the bypass occurs. We need to ensure this path also includes the stop logic.
  • site/src/api/queries/workspaces.ts:
    • changeVersion (line 162-186): This function calls API.changeWorkspaceVersion. It’s part of the chain of events leading to the bug.
    • updateWorkspace (line 188-210): This function calls API.updateWorkspace. Again, it’s a key player in the overall process.

By identifying these specific code locations, we can target our fixes more effectively. It’s like having a map that shows us exactly where we need to make changes. Knowing these locations helps us ensure we’re addressing the root cause and not just applying a band-aid solution.

Proposed Fix: The Solution We're Implementing

Alright, we've identified the problem, understood the root cause, and located the problematic code. Now, let's talk about the solution! Our proposed fix involves ensuring that both changeWorkspaceVersion and updateWorkspace functions follow the same consistent pattern – the one already correctly implemented in the non-dynamic params path of updateWorkspace.

Here's the code snippet we're going to use as our guide:

// Stop the workspace if it is already running.
if (workspace.latest_build.status === "running") {
 const stopBuild = await this.stopWorkspace(workspace.id);
 const awaitedStopBuild = await this.waitForBuild(stopBuild);
 // If the stop is canceled halfway through, we bail.
 if (awaitedStopBuild?.status === "canceled") {
 return Promise.reject(
 new Error("Workspace stop was canceled, not proceeding with version change."),
 );
 }
}

Let's break down what this code does:

  1. Check if the workspace is running: if (workspace.latest_build.status === "running") – This line checks the current status of the workspace. If it's running, we proceed to the next steps.
  2. Stop the workspace: const stopBuild = await this.stopWorkspace(workspace.id); – Here, we initiate the stop process for the workspace.
  3. Wait for the stop to complete: const awaitedStopBuild = await this.waitForBuild(stopBuild); – This is crucial. We need to wait for the workspace to fully stop before proceeding. This prevents resource conflicts.
  4. Handle cancellation:
     if (awaitedStopBuild?.status === "canceled") {

return Promise.reject( new Error("Workspace stop was canceled, not proceeding with version change."), ); } ``` This part checks if the stop process was canceled midway. If it was, we reject the promise and prevent the version change. This ensures we don't proceed with an incomplete stop.

Where will we apply this logic?

  1. In changeWorkspaceVersion: Before calling postWorkspaceBuild, we'll insert this code block. This will ensure that explicit version changes always stop the workspace first.
  2. In updateWorkspace's dynamic parameters path: We'll add this logic to the dynamic parameters path before calling postWorkspaceBuild. This will fix the bypass we identified earlier.

By implementing this fix, we're ensuring a consistent and reliable process for updating workspace template versions. This approach not only addresses the immediate bug but also strengthens the overall stability of our system.

Related Efforts: Building on Past Work

It's important to note that this fix isn't happening in isolation. We're building on previous efforts to improve workspace management. Specifically, two related items are worth mentioning:

  • PR #18425: This pull request was the original fix for the stop-before-start behavior. It laid the groundwork for ensuring workspaces stop before starting with a new version. However, as we've seen, the introduction of dynamic parameters and the changeWorkspaceVersion function created loopholes in this logic.
  • Dynamic parameters feature: The introduction of dynamic parameters, while a valuable addition, inadvertently bypassed the stop logic in the updateWorkspace function. This highlights the importance of thoroughly testing new features to ensure they don't introduce regressions.

Understanding these related efforts gives us context for the current fix. It shows that we're continuously working to improve our system and address any issues that arise. By learning from past experiences and building on previous work, we can create a more robust and reliable platform for our users.

In conclusion, by addressing this regression, we're ensuring that workspaces consistently stop before template version changes, preventing resource conflicts and maintaining system stability. Thanks for following along, and stay tuned for more updates!