[cocoapods] Proxy CocoaPods CDN source metadata

[sjchmiela]

Summary

Adds CocoaPods podspec metadata proxying to expo-cocoapods-proxy via CocoaPods supported :source_provider plugin hook.

When EAS_BUILD_COCOAPODS_CACHE_URL is set, the plugin now registers a proxied CDN source backed by the existing trunk repo directory, then registers canonical TrunkSource as fallback. The proxied source rewrites CocoaPods CDN metadata requests to ${EAS_BUILD_COCOAPODS_CACHE_URL}/cdn.cocoapods.org/ without creating or warming a separate second CDN repo.

Why

The existing proxy behavior covered pod source downloads through Pod::Downloader::Http and Pod::Downloader::Git, but CocoaPods CDN podspec metadata is resolved through Pod::CDNSource, bypassing those downloaders. That allowed podspec metadata requests to go directly to CocoaPods/GitHub and hit rate limits.

Behavior

• Podfiles without explicit source entries use the plugin-provided proxied source first.
• Cache misses can reuse the already-prewarmed local trunk repo directory.
• If the EAS CocoaPods cache source fails while resolving metadata, CocoaPods falls back to canonical trunk.
• Existing HTTP and Git downloader proxy behavior is unchanged.

Validation

Based on turtle-v2, iOS worker images use Ruby 3.2 and CocoaPods 1.13.0, 1.14.3, 1.15.2, or 1.16.2.

• Ruby 3.2.11 + CocoaPods 1.13.0 + ActiveSupport 6.1.7.6: 24 examples, 0 failures
• Ruby 3.2.11 + CocoaPods 1.14.3: 24 examples, 0 failures
• Ruby 3.2.11 + CocoaPods 1.15.2: 24 examples, 0 failures
• Ruby 3.2.11 + CocoaPods 1.16.2: 24 examples, 0 failures
• Ruby 3.3.9 + CocoaPods 1.13.0, 1.14.3, 1.15.2, 1.16.2: 24 examples, 0 failures for each version
• Ruby 3.3.9 + CocoaPods 1.12.0: 24 examples, 0 failures
• rubocop --disable-pending-cops on the modified Ruby files: no offenses
• git diff --check: clean

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.64%. Comparing base (64874f7) to head (32715f4).
⚠️ Report is 26 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3726      +/-   ##
==========================================
+ Coverage   56.51%   56.64%   +0.14%     
==========================================
  Files         887      892       +5     
  Lines       38416    38541     +125     
  Branches     8007     8024      +17     
==========================================
+ Hits        21707    21828     +121     
- Misses      16611    16615       +4     
  Partials       98       98              

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[github-actions]

⏩ The changelog entry check has been skipped since the "no changelog" label is present.

[github-actions]

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[Copilot]

Pull request overview

Adds CocoaPods CDN metadata proxying to expo-cocoapods-proxy by registering a proxied CDN source via CocoaPods’ :source_provider hook, enabling podspec metadata requests to go through EAS_BUILD_COCOAPODS_CACHE_URL (with trunk as a fallback) to reduce direct hits to CocoaPods/GitHub.

Changes:

• Introduces a FallbackableCDNSource and SourceProvider hook to add a proxied CDN source (and then canonical trunk) when EAS_BUILD_COCOAPODS_CACHE_URL is set.
• Registers the plugin as a default CocoaPods plugin so the hook runs even without explicit Podfile plugin configuration.
• Adds unit + integration specs that exercise proxied CDN usage and fallback behavior during pod install.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
packages/expo-cocoapods-proxy/lib/expo_cocoapods_proxy/proxy.rb	Adds :source_provider hook integration, proxied CDN source + fallback behavior, and default plugin registration.
packages/expo-cocoapods-proxy/spec/expo_cocoapods_proxy/proxy_spec.rb	Adds tests for source registration and end-to-end pod install behavior with proxy and fallback scenarios.

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