Propagate registration error (#34)

Author: stephen-soltesz

internal/setup/setup.go

@@ -55,7 +55,7 @@ func (f *File) Register(c *sql.Collector) error {
 		logx.Debug.Println("Unregister:", ok)
 		if !ok {
 			// This is a fatal error. If the
-			return fmt.Errorf("Failed to unregister %q", f.Name)
+			return fmt.Errorf("failed to unregister %q", f.Name)
 		}
 		f.c = nil
 	}
@@ -65,10 +65,10 @@ func (f *File) Register(c *sql.Collector) error {
 		// While collector Update could fail transiently, this may be a fatal error.
 		return err
 	}
-	logx.Debug.Println("Register: success:", f.Name)
+	logx.Debug.Println("Register:", f.Name, c.RegisterErr)
 	// Save the registered collector.
 	f.c = c
-	return nil
+	return c.RegisterErr
 }
 
 // Update runs the collector query again.

sql/collector.go

@@ -51,6 +51,9 @@ type Collector struct {
 	metrics []Metric
 	// mux locks access to types above.
 	mux sync.Mutex
+
+	// RegisterErr contains any error during registration. This should be considered fatal.
+	RegisterErr error
 }
 
 // NewCollector creates a new BigQuery Collector instance.
@@ -76,6 +79,7 @@ func (col *Collector) Describe(ch chan<- *prometheus.Desc) {
 		err := col.Update()
 		if err != nil {
 			log.Println(err)
+			col.RegisterErr = err
 		}
 		col.setDesc()
 	}