resource: automatic determine mirrors for glibc-bootstrap and PyPI resources

Library/Homebrew/env_config.rb

@@ -318,6 +318,10 @@ module EnvConfig
                      "outdated.",
         boolean:     true,
       },
+      HOMEBREW_PIP_INDEX_URL:                    {
+        description:  "If set, `brew install <formula>` will use this URL to download PyPI package resources.",
+        default_text: "`https://pypi.org/simple`.",
+      },
       HOMEBREW_PRY:                              {
         description: "If set, use Pry for the `brew irb` command.",
         boolean:     true,

Library/Homebrew/resource.rb

@@ -78,8 +78,11 @@ def owner=(owner)
   end
 
   def downloader
-    @downloader ||= download_strategy.new(url, download_name, version,
-                                          mirrors: mirrors.dup, **specs)
+    return @downloader if @downloader.present?
+
+    url, *mirrors = determine_url_mirrors
+    @downloader = download_strategy.new(url, download_name, version,
+                                        mirrors: mirrors, **specs)
   end
 
   # Removes /s from resource names; this allows Go package names
@@ -277,6 +280,31 @@ def detect_version(val)
     version unless version.null?
   end
 
+  def determine_url_mirrors
+    extra_urls = []
+
+    # glibc-bootstrap
+    if url.start_with?("https://github.com/Homebrew/glibc-bootstrap/releases/download")
+      if Homebrew::EnvConfig.artifact_domain.present?
+        extra_urls << url.sub("https://github.com", Homebrew::EnvConfig.artifact_domain)
+      end
+      if Homebrew::EnvConfig.bottle_domain != HOMEBREW_BOTTLE_DEFAULT_DOMAIN
+        tag, filename = url.split("/").last(2)
+        extra_urls << "#{Homebrew::EnvConfig.bottle_domain}/glibc-bootstrap/#{tag}/#{filename}"
+      end
+    end
+
+    # PyPI packages: PEP 503 – Simple Repository API <https://peps.python.org/pep-0503>
+    if Homebrew::EnvConfig.pip_index_url.present?
+      pip_index_base_url = Homebrew::EnvConfig.pip_index_url.chomp("/").chomp("/simple")
+      %w[https://files.pythonhosted.org https://pypi.org].each do |base_url|
+        extra_urls << url.sub(base_url, pip_index_base_url) if url.start_with?("#{base_url}/packages")
+      end
+    end
+
+    [*extra_urls, url, *mirrors].uniq
+  end
+
   # A resource containing a Go package.
   class Go < Resource
     def stage(target, &block)

Library/Homebrew/sorbet/rbi/hidden-definitions/hidden.rbi

@@ -2655,6 +2655,8 @@ module Homebrew::EnvConfig
 
   def self.no_proxy(); end
 
+  def self.pip_index_url(); end
+
   def self.pry?(); end
 
   def self.simulate_macos_on_linux?(); end