feat(logcli): Add timestamp format flag via cli argument for default output

cmd/logcli/main.go

@@ -28,14 +28,31 @@ import (
 )
 
 var (
-	app        = kingpin.New("logcli", "A command-line for loki.").Version(version.Print("logcli"))
-	quiet      = app.Flag("quiet", "Suppress query metadata").Default("false").Short('q').Bool()
+	app = kingpin.New("logcli", "A command-line for loki.").
+		Version(version.Print("logcli"))
+	quiet = app.Flag("quiet", "Suppress query metadata").
+		Default("false").
+		Short('q').
+		Bool()
 	statistics = app.Flag("stats", "Show query statistics").Default("false").Bool()
-	outputMode = app.Flag("output", "Specify output mode [default, raw, jsonl]. raw suppresses log labels and timestamp.").Default("default").Short('o').Enum("default", "raw", "jsonl")
-	timezone   = app.Flag("timezone", "Specify the timezone to use when formatting output timestamps [Local, UTC]").Default("Local").Short('z').Enum("Local", "UTC")
-	cpuProfile = app.Flag("cpuprofile", "Specify the location for writing a CPU profile.").Default("").String()
-	memProfile = app.Flag("memprofile", "Specify the location for writing a memory profile.").Default("").String()
-	stdin      = app.Flag("stdin", "Take input logs from stdin").Bool()
+	outputMode = app.Flag("output", "Specify output mode [default, raw, jsonl]. raw suppresses log labels and timestamp.").
+			Default("default").
+			Short('o').
+			Enum("default", "raw", "jsonl")
+	timezone = app.Flag("timezone", "Specify the timezone to use when formatting output timestamps [Local, UTC]").
+			Default("Local").
+			Short('z').
+			Enum("Local", "UTC")
+	outputTimestampFmt = app.Flag("output-timestamp-format", "Specify the format of timestamps in the default output mode [rfc3339, rfc3339nano, rfc822z, rfc1123z, stampmicro, stampmilli, stampnano,unixdate]").
+				Default("rfc3339").
+				Enum("rfc3339", "rfc3339nano", "rfc822z", "rfc1123z", "stampmicro", "stampmilli", "stampnano", "unixdate")
+	cpuProfile = app.Flag("cpuprofile", "Specify the location for writing a CPU profile.").
+			Default("").
+			String()
+	memProfile = app.Flag("memprofile", "Specify the location for writing a memory profile.").
+			Default("").
+			String()
+	stdin = app.Flag("stdin", "Take input logs from stdin").Bool()
 
 	queryClient = newQueryClient(app)
 
@@ -62,6 +79,8 @@ or provide specific start and end times with --from and --to respectively.
 Notice that when using --from and --to then ensure to use RFC3339Nano
 time format, but without timezone at the end. The local timezone will be added
 automatically or if using  --timezone flag.
+In default output mode the --output-timestamp-format flag can be used to 
+modify the output timestamp.
 
 Example:
 
@@ -72,6 +91,15 @@ Example:
 	   --output=jsonl
 	   'my-query'
 
+Example with --output-timestamp-format:
+
+	logcli query
+	   --timezone=UTC
+	   --from="2021-01-19T10:00:00Z"
+	   --to="2021-01-19T20:00:00Z"
+	   --output-timestamp-format=rfc3339nano
+	   'my-query'
+
 The output is limited to 30 entries by default; use --limit to increase.
 
 While "query" does support metrics queries, its output contains multiple
@@ -358,6 +386,25 @@ func main() {
 			ColoredOutput: rangeQuery.ColoredOutput,
 		}
 
+		switch *outputTimestampFmt {
+		case "rfc3339nano":
+			outputOptions.TimestampFormat = time.RFC3339Nano
+		case "rfc822z":
+			outputOptions.TimestampFormat = time.RFC822Z
+		case "rfc1123z":
+			outputOptions.TimestampFormat = time.RFC1123Z
+		case "stampmilli":
+			outputOptions.TimestampFormat = time.StampMilli
+		case "stampmicro":
+			outputOptions.TimestampFormat = time.StampMicro
+		case "stampnano":
+			outputOptions.TimestampFormat = time.StampNano
+		case "unixdate":
+			outputOptions.TimestampFormat = time.UnixDate
+		default:
+			outputOptions.TimestampFormat = time.RFC3339
+		}
+
 		out, err := output.NewLogOutput(os.Stdout, *outputMode, outputOptions)
 		if err != nil {
 			log.Fatalf("Unable to create log output: %s", err)

pkg/logcli/output/default.go

@@ -19,7 +19,12 @@ type DefaultOutput struct {
 
 // Format a log entry in a human readable format
 func (o *DefaultOutput) FormatAndPrintln(ts time.Time, lbls loghttp.LabelSet, maxLabelsLen int, line string) {
-	timestamp := ts.In(o.options.Timezone).Format(time.RFC3339)
+	format := o.options.TimestampFormat
+	if format == "" {
+		format = time.RFC3339
+	}
+
+	timestamp := ts.In(o.options.Timezone).Format(format)
 	line = strings.TrimSpace(line)
 
 	if o.options.NoLabels {

pkg/logcli/output/default_test.go

@@ -14,7 +14,7 @@ import (
 func TestDefaultOutput_Format(t *testing.T) {
 	t.Parallel()
 
-	timestamp, _ := time.Parse(time.RFC3339, "2006-01-02T15:04:05+07:00")
+	timestamp, _ := time.Parse(time.RFC3339Nano, "2006-01-02T15:04:05.123456789+07:00")
 	emptyLabels := loghttp.LabelSet{}
 	someLabels := loghttp.LabelSet(map[string]string{
 		"type": "test",
@@ -76,6 +76,22 @@ func TestDefaultOutput_Format(t *testing.T) {
 			"Hello",
 			"2006-01-02T08:04:05Z Hello\n",
 		},
+		"TimestampFormat using RFC3339Nano": {
+			&LogOutputOptions{Timezone: time.UTC, TimestampFormat: time.RFC3339Nano},
+			timestamp,
+			emptyLabels,
+			0,
+			"Hello",
+			"2006-01-02T08:04:05.123456789Z {} Hello\n",
+		},
+		"TimestampFormat using StampMicro truncated": {
+			&LogOutputOptions{Timezone: time.UTC, TimestampFormat: time.StampMicro},
+			timestamp,
+			emptyLabels,
+			0,
+			"Hello",
+			"Jan  2 08:04:05.123456 {} Hello\n",
+		},
 	}
 
 	for testName, testData := range tests {

pkg/logcli/output/output.go

@@ -33,17 +33,23 @@ type LogOutput interface {
 }
 
 // LogOutputOptions defines options supported by LogOutput
+// TimestampFormat can be one of RFC3339 (default), RFC3339Nano, RFC822Z, RFC1123Z, StampMilli, StampMicro, StampNano, UnixDate
 type LogOutputOptions struct {
-	Timezone      *time.Location
-	NoLabels      bool
-	ColoredOutput bool
+	Timezone        *time.Location
+	NoLabels        bool
+	ColoredOutput   bool
+	TimestampFormat string
 }
 
 // NewLogOutput creates a log output based on the input mode and options
 func NewLogOutput(w io.Writer, mode string, options *LogOutputOptions) (LogOutput, error) {
 	if options.Timezone == nil {
 		options.Timezone = time.Local
 	}
+	// in case TimestampFormat is not set, default to RFC3339
+	if options.TimestampFormat == "" {
+		options.TimestampFormat = time.RFC3339
+	}
 
 	switch mode {
 	case "default":

pkg/logcli/output/output_test.go

@@ -8,11 +8,12 @@ import (
 )
 
 func TestNewLogOutput(t *testing.T) {
-	options := &LogOutputOptions{time.UTC, false, false}
+	options := &LogOutputOptions{Timezone: time.UTC, NoLabels: false, ColoredOutput: false}
 
 	out, err := NewLogOutput(nil, "default", options)
 	assert.NoError(t, err)
 	assert.IsType(t, &DefaultOutput{nil, options}, out)
+	assert.Equal(t, time.RFC3339, out.(*DefaultOutput).options.TimestampFormat)
 
 	out, err = NewLogOutput(nil, "jsonl", options)
 	assert.NoError(t, err)