ETag in ResponseHeader is different from staticwebassets.endpoints.json

[CodAffection]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

This my program.cs files

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddControllersWithViews(options =>
  options.Filters.Add());

var app = builder.Build();

app.UseRouting();

app.UseAuthentication();
app.UseAuthorization();


app.MapStaticAssets();
app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Article}/{action=Index}/{id?}")
    .WithStaticAssets();

app.Run();

The problem is that for custom css and js file in wwwroot/css or wwwroot/js the ETag generated in staticwebassets.endpoints.json is not what returned for particular statis files in Response.Header ETag(Strong).

and there each time the file is getting download with 200Ok instead of 304 Not Modified Status

What am I missing.

staticwebassets.endpoints.json (only the object representing site.css)

Response Header

Expected Behavior

No response

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

No response

Anything else?

No response

[javiercn]

@CodAffection thanks for contacting us.

Do you see this during build/development or also publish?

[CodAffection]

@javiercn
After going through the source I found the reason here.

This is what I understood, through runtime patching the method-AttachRuntimePatching, applied a different ETag for non-minified files for cache-busting. Correct me if I'm wrong. Still I didn't understood how come the created ETag is not there in staticwebassets.endpoints.json file,

I have one doubt though, The entire cache-busting is starting from here. and the if clause is relying on configuration key-ReloadStaticAssetsAtRuntime, isn't this entire process should be discarded for non-development environment? why isn't that considered in the if clause?

[javiercn]

@CodAffection thanks for the additional details.

The way this works is that its only enabled during development unless you explicitly enable it through config (most of our development features work that way).

[CodAffection]

@javiercn thanks for your input, really appreciated

Meaning isBuildManifest will be false for non-development environment? just confirming.

And also do we need all mechanisms in any particular environment

• fingerprinted filename eg: site.xxx.cs
• query string versioning (through asp-append-version)
• ETag & Last-Modified date-based cache validation

wouldn't it be better to only use fingerprinted filename for production and disable it for development environment?
would like to hear your suggestion.

[javiercn]

@CodAffection thanks for the additional details.

Yes, IsBuildManifest is set to false in the manifest that we generate during publish.

And also do we need all mechanisms in any particular environment

Yes and no, and I'll explain. asp-append-version precedes all the work that we did with fingerprinting. As far as I can remember, it's compatible with it (if assets are configured, then we will automatically use the fingerprinted version instead of appending to the query string).

Appending to the query string is less desirable than changing the file path name, because any proxy server in the middle might choose to ignore the query string for caching/invalidation purposes (and there have been such cases in the past), while that can't be done for the path.

As for the ETag/Cache, it's complementary because we can't essentially fingerprint everything (for example, we don't rewrite CSS to add fingerprinted assets and there is no importmap mechanism like what it exists for JS, the day this exists, we would generate the same for other resources) so it is important that we setup no-cache and ETag for things that we can't fingerprint and we setup long cache times for immutable resources.

[CodAffection]

@javiercn You cleared lot of doubts that I've been holding on to myself.

But regarding fingerprinting for CSS, It is happening in a freshly created razor app, I've tried it with default route of the app, it is working without any additional work-for the default wwwroot/css/site.css file, obviously it's not <script type="importmap"></script>, It works even without the asp-append-version property

this is the program.cs file.

app.MapStaticAssets();
app.MapRazorPages()
   .WithStaticAssets();

what do you think it is? I think it is happening while converting razor template into html document.

and the same is not working when an MVC view is rendered. (Currently I'm using .NET Core 9)

Is in this what we are trying to achieve in brief?

[javiercn]

@CodAffection thanks for the additional details.

For files that are on the razor templates (for example, things that are referenced with ~/ we are able to automatically switch to the fingerprinted names, but for resources inside that .css file we are not. The reason is because we don't process the internals of the css file.

[javiercn]

and the same is not working when an MVC view is rendered. (Currently I'm using .NET Core 9)

This might be a bug.

[CodAffection]

@javiercn thanks for your contribution.

but for resources inside that .css file we are not.

I agree, if you are referring to @import url("reset.css");

This might be a bug.

Hope it will get fixed in next preview.