fix: ignore go-fuse ctx in Lookup (#675)

Ignore context passed into Lookup as it can be cancelled by
interrupts in go-fuse. Instead create a new context when Lookup
is invoked.

internal/proxy/fuse_test.go

@@ -27,6 +27,7 @@ import (
 
 	"github.com/GoogleCloudPlatform/alloydb-auth-proxy/alloydb"
 	"github.com/GoogleCloudPlatform/alloydb-auth-proxy/internal/proxy"
+	"github.com/hanwen/go-fuse/v2/fs"
 )
 
 func randTmpDir(t interface {
@@ -296,3 +297,24 @@ func TestFUSEWithBadDir(t *testing.T) {
 		t.Fatal("proxy client should fail with bad dir")
 	}
 }
+
+func TestLookupIgnoresContext(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping fuse tests in short mode.")
+	}
+	// create context and cancel it immediately
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	d := &fakeDialer{}
+	c, _ := newTestClient(t, d, randTmpDir(t), randTmpDir(t))
+
+	// invoke Lookup with cancelled context, should ignore context and succeed
+	_, err := c.Lookup(ctx, "proj.region.cluster.instance", nil)
+	if err != fs.OK {
+		t.Fatalf("proxy.Client.Lookup(): %v", err)
+	}
+	// Close the client to close all open sockets.
+	if err := c.Close(); err != nil {
+		t.Fatalf("c.Close(): %v", err)
+	}
+}

internal/proxy/proxy_other.go

@@ -99,7 +99,8 @@ func (c *Client) Readdir(_ context.Context) (fs.DirStream, syscall.Errno) {
 // socket is connected to the requested Cloud SQL instance. Lookup returns a
 // symlink (instead of the socket itself) so that multiple callers all use the
 // same Unix socket.
-func (c *Client) Lookup(ctx context.Context, instance string, _ *fuse.EntryOut) (*fs.Inode, syscall.Errno) {
+func (c *Client) Lookup(_ context.Context, instance string, _ *fuse.EntryOut) (*fs.Inode, syscall.Errno) {
+	ctx := context.Background()
 	if instance == "README" {
 		return c.NewInode(ctx, &readme{}, fs.StableAttr{}), fs.OK
 	}