grpc.Dial fails to connect to unix domain socket when https_proxy is set #8207
Description
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before submitting your issue.
What version of gRPC are you using?
google.golang.org/grpc v1.71.0
What version of Go are you using (go version)?
go version go1.23.6 linux/amd64
What operating system (Linux, Windows, …) and version?
Linux (glinux, recent)
What did you do?
If possible, provide a recipe for reproducing the error.
Repro is available in Ongy/go-grpc-repro@3c23732
The repro is quite minimal and requires introspection of the debug output to recognize the error.
What did you expect to see?
I expect Dial to try and connect to a unix:///... domain socket and then fail due to some error of type "file doesn't exist"
What did you see instead?
By looking at the debug output, I can determine that the proxy logic picks up the https_proxy for a URL of schema unix://. While this just leads to a different type of error in the repro, this leads to a real error in an application where the unix socket does exist.
❯ GRPC_GO_LOG_VERBOSITY_LEVEL=99 GRPC_GO_LOG_SEVERITY_LEVEL=info go run ./...
2025/03/28 15:17:16 INFO: [core] original dial target is: "unix:///var/run/test.sock"
2025/03/28 15:17:16 INFO: [core] [Channel #1]Channel created
2025/03/28 15:17:16 INFO: [core] [Channel #1]parsed dial target is: resolver.Target{URL:url.URL{Scheme:"unix", Opaque:"", User:(*url.Userinfo)(nil), Host:"", Path:"/var/run/test.sock", RawPath:"", OmitHost:false, ForceQuery:false, RawQuery:"", Fragment:"", RawFragment:""}}
2025/03/28 15:17:16 INFO: [core] [Channel #1]Channel authority set to "localhost"
2025/03/28 15:17:16 INFO: [delegating-resolver] Proxy URL detected : http://127.0.0.1
2025/03/28 15:17:16 INFO: [delegating-resolver] Addresses received from target resolver: [{Addr: "/var/run/test.sock", ServerName: "", Attributes: {"<%!p(networktype.keyType=grpc.internal.transport.networktype)>": "unix" }, }]
2025/03/28 15:17:16 INFO: [delegating-resolver] Addresses received from proxy resolver: [{Addr: "127.0.0.1:443", ServerName: "", }]
2025/03/28 15:17:16 INFO: [core] [Channel #1]Resolver state updated: {
"Addresses": [
{
"Addr": "127.0.0.1:443",
"ServerName": "",
"Attributes": {
"\u003c%!p(proxyattributes.keyType=grpc.resolver.delegatingresolver.proxyOptions)\u003e": "\u003c%!p(proxyattributes.Options={\u003cnil\u003e /var/run/test.sock})\u003e"
},
"BalancerAttributes": null,
"Metadata": null
}
],
"Endpoints": [
{
"Addresses": [
{
"Addr": "127.0.0.1:443",
"ServerName": "",
"Attributes": {
"\u003c%!p(proxyattributes.keyType=grpc.resolver.delegatingresolver.proxyOptions)\u003e": "\u003c%!p(proxyattributes.Options={\u003cnil\u003e /var/run/test.sock})\u003e"
},
"BalancerAttributes": null,
"Metadata": null
}
],
"Attributes": null
}
],
"ServiceConfig": null,
"Attributes": null
} (resolver returned new addresses)