[IMP] Error Handling and Tests

Signed-off-by: David Arnold <dar@devco.co>

plugins/inputs/uwsgi/uwsgi.go

@@ -1,3 +1,5 @@
+// Package uwsgi implements a telegraf plugin for
+// collecting uwsgi stats from the uwsgi stats server.
 package uwsgi
 
 import (
@@ -15,14 +17,53 @@ import (
 
 var timeout = 5 * time.Second
 
+// uWSGI Server struct
 type Uwsgi struct {
 	Servers []string `toml:"server"`
 }
 
+// Errors is a list of errors accumulated during an interval.
+type Errors []error
+
+func (errs Errors) Error() string {
+	s := ""
+	for _, err := range errs {
+		if s == "" {
+			s = err.Error()
+		} else {
+			s = s + ". " + err.Error()
+		}
+	}
+	return s
+}
+
+// NestedError wraps an error returned from deeper in the code.
+type NestedError struct {
+	// Err is the error from where the NestedError was constructed.
+	Err error
+	// NestedError is the error that was passed back from the called function.
+	NestedErr error
+}
+
+// Error returns a concatenated string of all the nested errors.
+func (ne NestedError) Error() string {
+	return ne.Err.Error() + ": " + ne.NestedErr.Error()
+}
+
+// Errorf is a convenience function for constructing a NestedError.
+func Errorf(err error, msg string, format ...interface{}) error {
+	return NestedError{
+		NestedErr: err,
+		Err:       fmt.Errorf(msg, format...),
+	}
+}
+
+// Description returns the plugin description
 func (u *Uwsgi) Description() string {
 	return "Read uWSGI metrics."
 }
 
+// SampleConfig returns the sample configuration
 func (u *Uwsgi) SampleConfig() string {
 	return `
     ## List with urls of uWSGI Stats servers. Url must match pattern:
@@ -34,17 +75,20 @@ func (u *Uwsgi) SampleConfig() string {
 `
 }
 
+// Gather collect data from uWSGI Server
 func (u *Uwsgi) Gather(acc telegraf.Accumulator) error {
+	var errs Errors
 	for _, s := range u.Servers {
 		n, err := url.Parse(s)
 		if err != nil {
 			return fmt.Errorf("Could not parse uWSGI Stats Server url '%s': %s", s, err)
 		}
-
-		u.gatherServer(acc, n)
+		if err := u.gatherServer(acc, n); err != nil {
+			errs = append(errs, Errorf(err, "server %s", s))
+		}
 
 	}
-	return nil
+	return errs
 }
 
 func (u *Uwsgi) gatherServer(acc telegraf.Accumulator, url *url.URL) error {
@@ -59,7 +103,7 @@ func (u *Uwsgi) gatherServer(acc telegraf.Accumulator, url *url.URL) error {
 	case "http":
 		resp, err := http.Get(url.String())
 		if err != nil {
-			return fmt.Errorf("Could not connect to uWSGI Stats Server '%s': %s", url.String(), err)
+			return Errorf(err, "Could not connect to uWSGI Stats Server '%s'", url.String())
 		}
 		r = resp.Body
 	default:
@@ -67,7 +111,7 @@ func (u *Uwsgi) gatherServer(acc telegraf.Accumulator, url *url.URL) error {
 	}
 
 	if err != nil {
-		return fmt.Errorf("Could not connect to uWSGI Stats Server '%s': %s", url.String(), err)
+		return Errorf(err, "Could not connect to uWSGI Stats Server '%s'", url.String())
 	}
 	defer r.Close()
 
@@ -75,11 +119,13 @@ func (u *Uwsgi) gatherServer(acc telegraf.Accumulator, url *url.URL) error {
 	s.Url = url.String()
 
 	dec := json.NewDecoder(r)
-	dec.Decode(&s)
+	if err := dec.Decode(&s); err != nil {
+		return Errorf(err, "Could not decode json payload from server '%s'", url.String())
+	}
 
 	u.gatherStatServer(acc, &s)
 
-	return nil
+	return err
 }
 
 func (u *Uwsgi) gatherStatServer(acc telegraf.Accumulator, s *StatsServer) {

plugins/inputs/uwsgi/uwsgi_test.go

@@ -123,3 +123,57 @@ func TestBasic(t *testing.T) {
 	var acc testutil.Accumulator
 	require.NoError(t, plugin.Gather(&acc))
 }
+
+func TestInvalidJason(t *testing.T) {
+	js := `
+{
+    "version":"2.0.12",
+    "listen_queue":0,
+    "listen_queue_errors":0,
+    "signal_queue":0,
+    "load":0,
+    "pid:28372
+    "uid":10
+}
+`
+
+	fakeServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/" {
+			_, _ = w.Write([]byte(js))
+		} else {
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+
+	defer fakeServer.Close()
+
+	plugin := &uwsgi.Uwsgi{
+		Servers: []string{fakeServer.URL + "/"},
+	}
+	var acc testutil.Accumulator
+	require.Error(t, plugin.Gather(&acc))
+}
+
+func TestHttpError(t *testing.T) {
+	plugin := &uwsgi.Uwsgi{
+		Servers: []string{"http://novalidurladress/"},
+	}
+	var acc testutil.Accumulator
+	require.Error(t, plugin.Gather(&acc))
+}
+
+func TestTcpError(t *testing.T) {
+	plugin := &uwsgi.Uwsgi{
+		Servers: []string{"tcp://novalidtcpadress/"},
+	}
+	var acc testutil.Accumulator
+	require.Error(t, plugin.Gather(&acc))
+}
+
+func TestUnixSocketError(t *testing.T) {
+	plugin := &uwsgi.Uwsgi{
+		Servers: []string{"unix:///novalidunixsocket"},
+	}
+	var acc testutil.Accumulator
+	require.Error(t, plugin.Gather(&acc))
+}