oauthex: build defaultDiscoveryTransport lazily instead of at import - #1278
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| func TestImportDoesNotCacheProxyEnv(t *testing.T) { | ||
| t.Setenv("HTTPS_PROXY", "http://127.0.0.1:9") | ||
| req, _ := http.NewRequest(http.MethodGet, "https://example.com/", nil) | ||
| got, err := http.ProxyFromEnvironment(req) | ||
| if err != nil || got == nil { | ||
| t.Fatalf("proxy not detected: got=%v err=%v", got, err) | ||
| } | ||
| } |
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this test fails when is not run in isolation
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Yeah, that's it — another discovery test calls newDiscoveryClient which calls defaultDiscoveryTransport() before my test, so ProxyFromEnvironment is already cached by the time my t.Setenv runs. It only passed because I ran it alone.
I'll drop the test. Since that proxy env is read once per process, any test I write here is at the mercy of whatever runs first, so it's not reliable. The change itself is small and the fix is clear.
is that okay ?
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let's drop the test, but leave a comment explaining why OnceValue is used, thanks for the fix!
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defaultDiscoveryTransport was a package-level var, so it got built the moment the package was imported. Building it runs proxyConfigured, which calls http.DefaultTransport's proxy func (that's http.ProxyFromEnvironment). The problem is net/http only reads the proxy env vars once and caches the result forever. So the first call wins, and here that first call happens at import time, before main() has had a chance to set HTTPS_PROXY. By the time the app sets it, it's already too late and the setting gets ignored. You didn't hit this in v1.7.0 because this code didn't exist yet. Just importing .../mcp pulls in oauthex, which was enough to trigger it even if you never called anything in the SDK. Fixing it by wrapping the setup in sync.OnceValue so it runs on first use instead of at import. By then the app has set its proxy env. It's still only built once and reused, same as before. Fixes modelcontextprotocol#1276
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Fixes #1276
What's happening
oauthexbuildsdefaultDiscoveryTransportas a package-level var, so itruns at import time. That path calls
proxyConfigured, which invokeshttp.DefaultTransport's proxy func (http.ProxyFromEnvironment). net/httpreads the proxy env vars only once and caches the result, so this import-time
call freezes the proxy config before
main()can setHTTPS_PROXY.New in v1.8.0, which is why it's a regression — just importing
.../mcp(which pulls in
oauthex) triggers it, even with no use of the SDK.Fix
Wrap the setup in
sync.OnceValueso it runs on first use instead of atimport. Still built once and reused.
Testing (removed)
replace: printsproxy=http://127.0.0.1:9now,proxy=<nil>before.oauthex.go test ./...passes.