add support for bunyan

.gitignore

@@ -11,6 +11,7 @@
 # Output of the go coverage tool.
 *.out
 coverage.html
+cover.html
 
 # Random pieces of test data I accumuate while writing this program.
 testlog

integration-tests/loggers_test.go

@@ -135,6 +135,33 @@ func TestLoggers(t *testing.T) {
 				l.Error("line 3", exampleError)
 			},
 		},
+		{
+			name: "bunyan",
+			ins: &parse.InputSchema{
+				LevelKey:    "level",
+				MessageKey:  "msg",
+				TimeKey:     "time",
+				LevelFormat: parse.BunyanV0LevelParser,
+				TimeFormat:  parse.DefaultTimeParser,
+				Strict:      true,
+				DeleteKeys:  []string{"v"},
+			},
+			f: func(buf *bytes.Buffer) {
+				// This is a node library.  We could bundle webpack and a JS
+				// interpreter, but I just ran this program and copied in the
+				// output.
+
+				// var bunyan = require("bunyan");
+				// var log = bunyan.createLogger({ name: "test" });
+				// log.info("line 1");
+				// log.info({ string: "value", int: 42, object: { foo: "bar" } }, "line 2");
+				// log.info({ error: "whoa" }, "line 3");
+				buf.Write([]byte(`{"level":30,"msg":"line 1","time":"2021-03-09T17:44:26.203Z","v":0}
+{"level":30,"string":"value","int":42,"object":{"foo":"bar"},"msg":"line 2","time":"2021-03-09T17:44:26.204Z","v":0}
+{"level":30,"error":"whoa","msg":"line 3","time":"2021-03-09T17:44:26.204Z","v":0}
+`))
+			},
+		},
 	}
 
 	f := &ignoreTimeFormatter{

pkg/parse/default_parsers.go

@@ -91,6 +91,28 @@ func LagerLevelParser(in interface{}) (Level, error) {
 	}
 }
 
+// BunyanV0LLevelParser maps bunyan's float64 levels to log levels.
+func BunyanV0LevelParser(in interface{}) (Level, error) {
+	x, ok := in.(float64)
+	if !ok {
+		return LevelUnknown, fmt.Errorf("invalid bunyan log level %T(%v), want float64", in, in)
+	}
+	if x <= 10 {
+		return LevelTrace, nil
+	} else if x <= 20 {
+		return LevelDebug, nil
+	} else if x <= 30 {
+		return LevelInfo, nil
+	} else if x <= 40 {
+		return LevelWarn, nil
+	} else if x <= 50 {
+		return LevelError, nil
+	} else if x <= 60 {
+		return LevelFatal, nil
+	}
+	return LevelUnknown, fmt.Errorf("invalid bunyan log level %v", x)
+}
+
 // DefaultLevelParser uses common strings to determine the log level.  Case does not matter; info is
 // the same log level as INFO.
 func DefaultLevelParser(in interface{}) (Level, error) {

pkg/parse/default_parsers_test.go

@@ -80,6 +80,14 @@ func TestLevelParsers(t *testing.T) {
 		{float64(1), LagerLevelParser, LevelInfo, false},
 		{float64(2), LagerLevelParser, LevelError, false},
 		{float64(3), LagerLevelParser, LevelFatal, false},
+		{float64(10), BunyanV0LevelParser, LevelTrace, false},
+		{float64(20), BunyanV0LevelParser, LevelDebug, false},
+		{float64(30), BunyanV0LevelParser, LevelInfo, false},
+		{float64(40), BunyanV0LevelParser, LevelWarn, false},
+		{float64(50), BunyanV0LevelParser, LevelError, false},
+		{float64(60), BunyanV0LevelParser, LevelFatal, false},
+		{"foo", BunyanV0LevelParser, LevelUnknown, true},
+		{float64(61), BunyanV0LevelParser, LevelUnknown, true},
 	}
 	for i, test := range testData {
 		got, err := test.parser(test.in)

pkg/parse/parse.go

@@ -48,6 +48,10 @@ type InputSchema struct {
 	// If true, print an error when non-JSON lines appear in the input.  If false, treat them
 	// as normal messages with as much information extracted as possible.
 	Strict bool
+
+	// DeleteKeys contains a list of keys to delete; used when the log lines contain version
+	// information that is used for guessing the schema.
+	DeleteKeys []string
 }
 
 // OutputFormatter describes an object that actually does the output formatting.  Methods take a
@@ -345,6 +349,18 @@ func (s *InputSchema) guessSchema(l *line) {
 		s.MessageKey = "message"
 		return
 	}
+	if has("time") && has("level") && has("v") && has("msg") {
+		// bunyan
+		if v, ok := l.fields["v"].(float64); ok && v == 0 {
+			s.TimeKey = "time"
+			s.TimeFormat = DefaultTimeParser // RFC3339
+			s.LevelKey = "level"
+			s.LevelFormat = BunyanV0LevelParser
+			s.MessageKey = "msg"
+			s.DeleteKeys = append(s.DeleteKeys, "v")
+			return
+		}
+	}
 	if has("time") && has("level") && has("msg") {
 		// logrus default json encoder
 		s.TimeKey = "time"
@@ -430,6 +446,9 @@ func (s *InputSchema) ReadLine(l *line) error {
 	} else {
 		pushError(fmt.Errorf("no level key %q in incoming log", s.LevelKey))
 	}
+	for _, k := range s.DeleteKeys {
+		delete(l.fields, k)
+	}
 	return retErr
 }