Describe the bug
When running gh cs ssh we forward the codespaces internal port (16634) in order to connect via GRPC.
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// Tunnel the remote gRPC server port to the local port |
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go func() { |
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// Start forwarding the port locally |
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opts := portforwarder.ForwardPortOpts{ |
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Port: codespacesInternalPort, |
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Internal: true, |
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} |
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ch <- fwd.ForwardPortToListener(pfctx, opts, listener) |
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}() |
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var conn *grpc.ClientConn |
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go func() { |
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// Attempt to connect to the port |
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opts := []grpc.DialOption{ |
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grpc.WithTransportCredentials(insecure.NewCredentials()), |
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} |
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conn, err = grpc.NewClient(localAddress, opts...) |
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ch <- err // nil if we successfully connected |
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}() |
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// Wait for the connection to be established or for the context to be cancelled |
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select { |
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case <-ctx.Done(): |
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return nil, ctx.Err() |
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case err := <-ch: |
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if err != nil { |
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return nil, err |
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} |
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} |
Both the port forward and the grpc client construction write to ch when completing, then the select unblocks. However, we've seen port forwarding fail but grpc client construction succeed, resulting in a failure much down the line that was not surfaced.
Affected version
➜ gh version
gh version 2.74.2 (2025-06-17)
https://github.com/cli/cli/releases/tag/v2.74.2
Steps to reproduce the behavior
Not possible to produce without a port forwarding issue or code changes.
Apply the following patch and see that the error doesn't bubble up:
diff --git a/internal/codespaces/rpc/invoker.go b/internal/codespaces/rpc/invoker.go
index 6ba8843ac..d1d19e5b9 100644
--- a/internal/codespaces/rpc/invoker.go
+++ b/internal/codespaces/rpc/invoker.go
@@ -5,6 +5,7 @@ package rpc
import (
"context"
+ "errors"
"fmt"
"net"
"os"
@@ -104,12 +105,8 @@ func connect(ctx context.Context, fwd portforwarder.PortForwarder) (Invoker, err
// Tunnel the remote gRPC server port to the local port
go func() {
- // Start forwarding the port locally
- opts := portforwarder.ForwardPortOpts{
- Port: codespacesInternalPort,
- Internal: true,
- }
- ch <- fwd.ForwardPortToListener(pfctx, opts, listener)
+ time.Sleep(time.Second)
+ ch <- errors.New("omg")
}()
var conn *grpc.ClientConn
Describe the bug
When running
gh cs sshwe forward the codespaces internal port (16634) in order to connect via GRPC.cli/internal/codespaces/rpc/invoker.go
Lines 105 to 133 in 4c47bad
Both the port forward and the grpc client construction write to
chwhen completing, then theselectunblocks. However, we've seen port forwarding fail but grpc client construction succeed, resulting in a failure much down the line that was not surfaced.Affected version
Steps to reproduce the behavior
Not possible to produce without a port forwarding issue or code changes.
Apply the following patch and see that the error doesn't bubble up: