Blazor WASM: Javascript/css not compressing when using Brotli web.config

[Schoof-T]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When hosting a Blazor WASM application, I want to use brotli compression for the best compression possible. However when using the Microsoft suggested web.config (https://raw.githubusercontent.com/dotnet/AspNetCore.Docs/main/aspnetcore/blazor/host-and-deploy/webassembly/_samples/web.config) mine/external libraries their javascript/css files are not longer compressed.

When using the default generated web.config, the .js and .css files are compressed.

My IIS has the following installed and enabled:

• https://learn.microsoft.com/en-us/iis/extensions/iis-compression/iis-compression-overview#installation
• https://iis-umbraco.azurewebsites.net/downloads/microsoft/url-rewrite
• 
• 

Expected Behavior

I would expect the .js and .css files to also be compressed, preferebly in brotli or otherwise in gzip.

Steps To Reproduce

• create a new Blazor WASM (not hosted) application
• run dotnet publish -c release
• host the application in IIS
• Note that all content is now GZIP compressed
• Update the pre-generated web.config to the Microsoft provided one (https://raw.githubusercontent.com/dotnet/AspNetCore.Docs/main/aspnetcore/blazor/host-and-deploy/webassembly/_samples/web.config)
• Note now that only the files in the _framework folder are compressed. (But as brotli)

Exceptions (if any)

No response

.NET Version

.NET 7

Anything else?

A secondary question, is it possible to generate the brotli web.config when running dotnet publish? Is this the correct way to do this? https://learn.microsoft.com/en-us/aspnet/core/blazor/host-and-deploy/webassembly?view=aspnetcore-7.0

[javiercn]

@Schoof-T thanks for contacting us.

I don't think the web.config applies to files that are not part of the blazor payload. That is, during publish we will compress the Blazor runtime and related files, but we won't be compressing any other static file that you add/bring.

The configuration in the web.config requires the file to have been statically compressed to serve a compressed version. You can tweak the web.config to compress all the files or to enable dynamic compression on the ones that are not statically compressed, but that's something that we can't offer guidance on.

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[Schoof-T]

@Schoof-T thanks for contacting us.

I don't think the web.config applies to files that are not part of the blazor payload. That is, during publish we will compress the Blazor runtime and related files, but we won't be compressing any other static file that you add/bring.

The configuration in the web.config requires the file to have been statically compressed to serve a compressed version. You can tweak the web.config to compress all the files or to enable dynamic compression on the ones that are not statically compressed, but that's something that we can't offer guidance on.

Thank you for the reply, that makes sense. Is there a reason why you are not compressing other files that I'm adding? I feel like that's a great way to optimize the size of a Blazor App. Might also be a good idea to add this information to the docs, because now just enabling the Brotli web.config has actually increased the file size of my Blazor App.

I'm having a difficult time finding guidance on how to optimize the the files I added in combination with the brotli compression.

[Schoof-T]

I have started noticing even stranger things now. I managed to get the brotli compression working with the default generated web.config (I didn't retry the default web.config after installing IIS Compression)

I publish with dotnet publish --configuration Release --self-contained true --runtime win-x64.
But the file size of the some dll's are larger than with the microsoft provided web.config.

Auto generated web.config

Microsoft provided web.config

The web.config that gets auto generated for me is the following:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <staticContent>
      <remove fileExtension=".blat" />
      <remove fileExtension=".dat" />
      <remove fileExtension=".dll" />
      <remove fileExtension=".json" />
      <remove fileExtension=".wasm" />
      <remove fileExtension=".woff" />
      <remove fileExtension=".woff2" />
      <mimeMap fileExtension=".blat" mimeType="application/octet-stream" />
      <mimeMap fileExtension=".dll" mimeType="application/octet-stream" />
      <mimeMap fileExtension=".dat" mimeType="application/octet-stream" />
      <mimeMap fileExtension=".json" mimeType="application/json" />
      <mimeMap fileExtension=".wasm" mimeType="application/wasm" />
      <mimeMap fileExtension=".woff" mimeType="application/font-woff" />
      <mimeMap fileExtension=".woff2" mimeType="application/font-woff" />
    </staticContent>
    <httpCompression>
      <dynamicTypes>
        <add mimeType="application/octet-stream" enabled="true" />
        <add mimeType="application/wasm" enabled="true" />
      </dynamicTypes>
    </httpCompression>
    <rewrite>
      <rules>
        <rule name="Serve subdir">
          <match url=".*" />
          <action type="Rewrite" url="wwwroot\{R:0}" />
        </rule>
        <rule name="SPA fallback routing" stopProcessing="true">
          <match url=".*" />
          <conditions logicalGrouping="MatchAll">
            <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
          </conditions>
          <action type="Rewrite" url="wwwroot\" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

The .br files are all available after the publish. But IIS is still doing something different.

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[mkArtakMSFT]

Closing as a dupe of #52824