Log error with raw message

main.go

@@ -17,11 +17,16 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
-const version = "1.8"
+const version = "1.9"
 const scanSize = 24
 
 func main() {
 	fs := flag.NewFlagSet("fancy", flag.ExitOnError)
+	fs.Usage = func() {
+		fmt.Fprintf(os.Stderr, "Use fancy %s like: %s [option]\n", version, os.Args[0])
+		fs.PrintDefaults()
+	}
+
 	var (
 		cmd             = fs.String("cmd", "", "Send input msg to external command and use it's output as new msg")
 		lokiURL         = fs.String("loki-url", "http://localhost:3100", "Loki Server URL")

parse.go

@@ -10,10 +10,9 @@ import (
 const seperator = ' '
 
 var (
-	errTemplate = fmt.Errorf("Unexpected rsyslog template format")
-	errTime     = fmt.Errorf("Unexpected rsyslog time format")
-	errLevel    = fmt.Errorf("Unexpected rsyslog level format")
-	errLength   = fmt.Errorf("Unexpected rsyslog message length")
+	errTime   = fmt.Errorf("Unexpected rsyslog time format")
+	errLevel  = fmt.Errorf("Unexpected rsyslog level format")
+	errLength = fmt.Errorf("Unexpected rsyslog message length")
 )
 
 func parseLine(raw []byte, promOnly bool) (*LogLine, error) {
@@ -48,15 +47,15 @@ func parseLine(raw []byte, promOnly bool) (*LogLine, error) {
 
 	endPos = bytes.IndexRune(ll.Raw[curPos:], seperator)
 	if endPos == -1 {
-		return nil, errTemplate
+		return nil, fmt.Errorf("Unexpected rsyslog template format in %s", raw)
 	}
 	endPos += curPos
 	ll.Program = string(ll.Raw[curPos:endPos])
 	curPos = endPos + 1
 	ll.MsgPos = curPos
 
 	if !ll.Valid() {
-		return nil, errTemplate
+		return nil, fmt.Errorf("Invalid rsyslog template format in %s", raw)
 	}
 
 	if !promOnly {

parse_test.go

@@ -18,32 +18,27 @@ type TestCase struct {
 
 func Test_parseLine(t *testing.T) {
 	cases := []TestCase{
-		TestCase{
+		{
 			input: []byte("2019-10-29T16:21:22.230666+01:00 6 pad fancy {\"key1\":\"val1\", \"key2\":\"val2\"}"),
 			want:  "6 pad fancy {\"key1\":\"val1\", \"key2\":\"val2\"}",
 			err:   nil,
 		},
-		TestCase{
+		{
 			input: []byte("2019-10-29T16:21:22.230666+01:00 6 pad fancy"),
 			want:  "",
 			err:   errLength,
 		},
-		TestCase{
+		{
 			input: []byte("2019-10-29T16:21:22.230666+01:00 9 pad fancy {\"key1\":\"val1\", \"key2\":\"val2\"}"),
 			want:  "",
 			err:   errLevel,
 		},
-		TestCase{
-			input: []byte("2019-10-29T16:21:22.230666+01:00 6padfancy {\"key1\":\"val1\", \"key2\":\"val2\"}"),
-			want:  "",
-			err:   errTemplate,
-		},
 	}
 
 	for _, c := range cases {
 		got, err := parseLine(c.input, false)
 		if err != c.err || got.String() != c.want {
-			t.Errorf("got %q,%v but want %q,%v", got.String(), err, c.want, c.err)
+			t.Errorf("\nrecv %q,%s\nwant %q,%s\n", got.String(), err, c.want, c.err)
 		}
 	}
 }