Azure-docs: Azure App Service on Linux FAQ needs a disclaimer about WebSockets

[prajaybasu]

There needs to be a dedicated disclaimer (with appropriate formatting to make it visible) to disable the permessage-deflate extension for WebSockets (as a limitation) that is not language centric (i.e. not Node.js only).

ASP.NET Core or any other language using WebSockets is affected. For example, my Blazor SPA using SignalR seems to be affected by this limitation: aspnet/AspNetCore#10370 - the mitigation steps only applies to sockets.io in Node.js and would not help me. It would have certainly helped me find the cause of WebSockets failing in App Service for Linux faster if the section about WebSockets was not buried in a FAQ question about sockets.io on Node.js

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Document Details

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• ID: b421fa01-1f39-28a5-78c2-63dd5700c8c5
• Version Independent ID: 10ed9c91-16e0-d371-fcfc-d6d5a7f984b2
• Content: App Service on Linux FAQ - Azure
• Content Source: articles/app-service/containers/app-service-linux-faq.md
• Service: app-service
• GitHub Login: @YiLi
• Microsoft Alias: yili

[AshokPeddakotla-MSFT]

@prajaybasu Thanks for the feedback! We are currently investigating and will update you shortly.

[AjayKumar-MSFT]

@prajaybasu, Thanks for the feedback! I have assigned the issue to the content author to review further and update the document as appropriate.

[yiliaomsft]

Are you saying your .NET Core web app is affected by this limitation? If so please send your web app name and we can take a look.

[AjayKumar-MSFT]

@prajaybasu, Since we have not heard back from you we will now proceed to close this thread. If there are further questions regarding this matter, please tag us in your reply. We will gladly reopen the issue and continue the discussion.

[amistry79]

Please reopen this thread since I am running into similar situation where WebSocket must be enabled for linux based app service and we do not have nodejs application with socket.io. See the reported github issue here https://github.com/microsoft/botbuilder-js/issues/1183

[AjayKumar-MSFT]

Amit, Just to confirm, are you stating that .NET Core WebApp is affected by this limitation as yiliaomsft mentioned? Could you please describe more details on your scenario?
Or, Since the issue is not related to document, we recommend posting technical questions on the technical forum where one of our specialized engineers in the subject or the Azure community members can provide the best possible answer to your scenario or kindly continue your discussion on the other GitHub issue.

[amistry79]

Ajay, Yes, the issue is not with documentation however issue with WebApp with Linux based app service which does not support WebSocket. In case, if we have support for WebSocket on Linux based App Service then please update the document. Hope this helps...

[AjayKumar-MSFT]

Thank you Amit for your feedback!
@yiliaomsft, Requesting your insights and review further on this topic.

[mcblair]

We're seeing this as well. .NET Core 3.0 Blazor Server-Side App. Default blazor template, no changes. We don't even see the option for websockets on our app service in azure. So unfortunately the websocket doesn't open and the performance and behavior of the app is far from desired.

[AjayKumar-MSFT]

I have been discussing on this internally with the product team and the content author, this is being reviewed further and I’ll post back as soon as I have more update.

Having said that, the Azure portal shows only features that currently work for Web App for Containers. As we enable more features, they will become visible on the portal.

Screenshot 1- Shows Web Sockets feature available on native (Windows platform) App Service.

Screenshot 2: Screen capture of Linux App Service with no Web Sockets settings.
ssssss

[jcmontx]

Hello,

Any updates on this issue?

I have a ASP.NET Core MVC app running on a Linux Web App and WebSockets are not working.

[AjayKumar-MSFT]

@btardif, Requesting your advise on this.

[jcmontx]

@AjayKumar-MSFT for a quick workaround I went for Azure SignalR.

[JennyLawrance]

@jcmontx Can you share your app please? (Send a repo or zip file to jennylaw(at)microsoft.com)

[ezenwankwogabriel]

I had similar issues on Node. socket.io was failing on App services run on Linux on an azure cdn hosted domain.
Was able to mitigate this by using the Custom Domain and TLS/SSL settings to link my domain to the app service url instead of setting up an azure cdn on the app service.

[theweiweiway]

@ezenwankwogabriel can you share your SSL settings? I'm having the same problem, Linux container with node 12 and websockets is enabled. I have a custom domain set up and my DNS is on cloudflare. However I can't connect from my client and I keep getting 503 error.

[ezenwankwogabriel]

@theweiweiway after setting up custom domain

On the TSL/SSL tab, Private Key Certificate (.pfx), i generate a private key for my domain name created previously by clicking on the Create App Serviced Managed Certificate

On the dialog the pops up, choose the domain and generate private key which can now be used on the custom domain tab to link to the private key to the domain name.

[theweiweiway]

Thanks @ezenwankwogabriel, but it didn't work for me :(

[michalczerwinski]

Still have the same issue for app service linux and Blazor 3.1. What is the status of this one?

[Corstiaan84]

Same issue on Linux B1

Update: after some investigation, I found some non-Blazor related errors that we causing the behavior. However, the app now works, although the console still shows a Blazor js failing with a 503 which led me to believe the issue was Blazor related when in fact it wasn't.