Change the headers of static files in Asp.net Core

Question

I am using package Microsoft.AspNet.StaticFiles and configuring it in Startup.cs as app.UseStaticFiles(). How can I change the headers

Answer 1

If you're looking for a solution allowing you to configure different behaviours for each environment (development, production & more), which is also the point of having these settings in the web.config file instead of hard-coding the whole stuff, you could consider the following approach.

Add the following key/value section in the appsettings.json file:

  "StaticFiles": {
    "Headers": {
      "Cache-Control": "no-cache, no-store",
      "Pragma": "no-cache",
      "Expires": "-1"
    }
  }

Then add the following in the Startup.cs file's Configure method accordingly:

app.UseStaticFiles(new StaticFileOptions()
{
    OnPrepareResponse = (context) =>
    {
        // Disable caching for all static files.
        context.Context.Response.Headers["Cache-Control"] = Configuration["StaticFiles:Headers:Cache-Control"];
        context.Context.Response.Headers["Pragma"] = Configuration["StaticFiles:Headers:Pragma"];
        context.Context.Response.Headers["Expires"] = Configuration["StaticFiles:Headers:Expires"];
    }
});

This will allow the developer to define different cache settings using different/multiple/cascading settings files (appsettings.json, appsettings.production.json and so on) - which is something that could be done with the old web.config configuration pattern - with the ASP.NET Core's new one.

For additional info regarding the topic I also suggest to read this post on my blog and/or these great articles from the official ASP.NET Core docs:

• Configuration
• Working with Static Files