Mark err as downstream if its from the secure socks proxy (#1136)

backend/proxy/secure_socks_proxy.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/grafana/grafana-plugin-sdk-go/backend/log"
+	"github.com/grafana/grafana-plugin-sdk-go/experimental/status"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"golang.org/x/net/proxy"
@@ -334,6 +335,9 @@ func (d *instrumentedSocksDialer) DialContext(ctx context.Context, n, addr strin
 		log.DefaultLogger.Error("received err from dialer", "network", n, "addr", addr, "err", err)
 		code = "dial_error"
 	}
+	if err != nil {
+		err = status.DownstreamError(err)
+	}
 
 	secureSocksRequestsDuration.WithLabelValues(code, d.datasourceName, d.datasourceType).Observe(time.Since(start).Seconds())
 	return c, err

backend/proxy/secure_socks_proxy_test.go

@@ -350,7 +350,7 @@ func TestInstrumentedSocksDialer(t *testing.T) {
 		c, err := cd.DialContext(context.Background(), "n", "addr")
 		assert.Nil(t, c)
 		assert.NotNil(t, err)
-		assert.Equal(t, "custom error", err.Error())
+		assert.Equal(t, "downstream error: custom error", err.Error())
 	})
 }