CNTRLPLANE-3751: Add dynamic proxy CA reload for outbound IdP transports

[tchap]

When PROXY_TRUSTED_CA_FILE is set, the OAuth Server watches the proxy CA file on disk and rebuilds outbound HTTP transports when it changes. The proxy CA is combined with any static IdP CA in the transport's RootCAs, so TLS-intercepting or HTTPS proxies are trusted alongside IdP endpoints.

The dynamicCARoundTripper uses DynamicFileCAContent (fsnotify + periodic poll) and swaps the underlying transport atomically. On reload failure the old transport is preserved.

Summary by CodeRabbit

• New Features

  • Added support for dynamically updating trusted CA certificates used by OAuth-related outbound connections.
  • OAuth and password-auth connections can now use proxy-trusted CA settings from server configuration.

• Bug Fixes

  • Improved TLS client setup for authentication and provider requests, including better handling of certificate, key, and CA combinations.
  • Fixed CA reload behavior so existing connections remain usable while trust settings update in the background.

[openshift-ci-robot]

@tchap: This pull request references CNTRLPLANE-3751 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "5.0.0" version, but no target version was set.

Details

In response to this:

When PROXY_TRUSTED_CA_FILE is set, the OAuth Server watches the proxy CA file on disk and rebuilds outbound HTTP transports when it changes. The proxy CA is combined with any static IdP CA in the transport's RootCAs, so TLS-intercepting or HTTPS proxies are trusted alongside IdP endpoints.

The dynamicCARoundTripper uses DynamicFileCAContent (fsnotify + periodic poll) and swaps the underlying transport atomically. On reload failure the old transport is preserved.

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[openshift-ci]

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[coderabbitai]

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Walkthrough

Adds a dynamicCARoundTripper that hot-reloads a proxy trusted CA bundle from a file, using an atomically-swapped http.Transport. OAuthServerConfig gains proxyTrustedCA (from PROXY_TRUSTED_CA_FILE env) and dynamicTransports fields; transport construction is moved to (*OAuthServerConfig).transportFor, which routes through the dynamic or static path; a post-start hook starts all dynamic watchers.

Changes

Dynamic Proxy CA Transport

Layer / File(s)	Summary
ExtraOAuthConfig fields and startup hook pkg/oauthserver/oauth_apiserver.go	ExtraOAuthConfig gains proxyTrustedCA and dynamicTransports fields. NewOAuthServerConfig reads PROXY_TRUSTED_CA_FILE into proxyTrustedCA. A new postStartHook (openshift.io-StartDynamicCAWatchers) starts each dynamicTransport's run(ctx) in a goroutine.
dynamicCARoundTripper implementation pkg/oauthserver/dynamic_transport.go	New file introduces dynamicCARoundTripper: constructor loads DynamicFileCAContent and builds the initial transport; buildTransport assembles an x509.CertPool from optional IdP CA file and current proxy CA bundle; Enqueue atomically swaps in a new transport and closes idle connections on the old one; RoundTrip delegates to the atomic transport; run starts the file watcher.
OAuthServerConfig.transportFor pkg/oauthserver/auth.go	Package-level transportFor/transportForInner replaced by (*OAuthServerConfig).transportFor and (*OAuthServerConfig).transportForInner. When proxyTrustedCA is set, creates and registers a dynamicCARoundTripper; otherwise builds a static TLS transport. All callers in getOAuthProvider and getPasswordAuthenticator updated to use c.transportFor(...).
Tests pkg/oauthserver/dynamic_transport_test.go	Adds helpers for ephemeral CA/cert generation and TLS test servers. Five test cases: proxy-CA-only, combined IdP+proxy CAs, hot-reload after PEM overwrite, error resilience on corrupt PEM, and constructor failure on nonexistent file.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

Tools execution failed with the following error:

Failed to run tools: 13 INTERNAL: Received RST_STREAM with code 2 (Internal server error)

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[tchap]

/jira refresh

[openshift-ci-robot]

@tchap: This pull request references CNTRLPLANE-3751 which is a valid jira issue.

Details

In response to this:

/jira refresh

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.

[openshift-ci]

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