Extension development for code-server compatibility

[diraneyya]

Hello everyone (and mostly @code-asher).

I am in the process of creating a PR for the vscode extension for Evidence, an awesome reporting tool, here evidence-dev/evidence#3201

The issue I am facing is that depending on whether the user is using vscode locally or via code-server, providing a seamless experience requires different measure.

Namely, unlike in native vscode, port forwarding works entirely differently in code-server. This is an important distinction for someone running the extension on a remote machine using code-server from Coder.

Is there a way to detect that we are running inside of a code-server, as compared to vscode natively, and what is the recommended way to interact with the auto port forwarding feature. Namely, when the user does not specify a preferred port or when the port is occupied and the command ends up running on a different port. This is a time where probing the auto forwarder asking for the actual port can be of great use.

Any level of information or a hint into where to look would be great.

Kind regards,
Orwa.

[diraneyya]

After posting the message above, I stumbled upon this https://code.visualstudio.com/api/advanced-topics/remote-extensions which explained a lot, however, I still have more questions.

I learnt more about auto port-forwarding and the function vscode.env.asExternalUri which gives back the port-forwarded URL's (ending with /proxy/{{port}}) but there is something that I still do not understand.

Namely, I have been struggling with performance issues in code-server which got me thinking about memory leaks and how most extension developers do not think about remote development. One unique thing about remote development is that you can close the window anytime. Namely, I do not see how the extension can get any time to cleanup.

In the code of the extension I am creating a PR for, there are a lot of so-called disposables, and I want to know if these are compatible with extensions running in a workspace remotely using code-server.

Any hints or links that you can offer me will be highly appreciated.

[code-asher]

Yeah back when I investigated this (a long time ago now), when the browser window closes the extension host process is immediately killed, and extensions are given no time to clean up. I am pretty sure the disposables are never called, or at least they were not last I checked. Not sure if things have changed since then, but it sounds like they have not.

The VS Code folks would know more, but I think this is where it happens: https://github.com/microsoft/vscode/blob/bf0108fb1e1321b025449650e6710f18116d5e64/src/vs/server/node/remoteExtensionHostAgentServer.ts#L477

When the connection is closed, the extension host is disposed, which if you follow through appears to immediately kill the process: https://github.com/microsoft/vscode/blob/bf0108fb1e1321b025449650e6710f18116d5e64/src/vs/server/node/extensionHostConnection.ts#L231

Ideally, it would let all the extensions clean up first. Unless that changes, I think extensions will have to consider they could be killed at any time. Of course, this is good practice anyway since a process can crash unexpectedly, but it does seem like a bug given how native VS Code works versus web VS Code. Assuming I am looking at this right, I could be wrong about it all. I am not actually sure disposals work consistently in even native VS Code.

[diraneyya]

evidence-dev/evidence#3201