cmd: add --report-summary flag

Add --report-summary flag for "k6 run", the parameter is output file to
write report summary in JSON format. Empty string means output to
standard out.

Close #355

cmd/config.go

@@ -54,17 +54,20 @@ func configFlagSet() *pflag.FlagSet {
 	flags.Bool("no-usage-report", false, "don't send anonymous stats to the developers")
 	flags.Bool("no-thresholds", false, "don't run thresholds")
 	flags.Bool("no-summary", false, "don't show the summary at the end of the test")
+	reportSummaryUsage := "output summary to file in json format, empty string means output to standard out"
+	flags.StringP("report-summary", "r", "", reportSummaryUsage)
 	return flags
 }
 
 type Config struct {
 	lib.Options
 
-	Out           []string  `json:"out" envconfig:"out"`
-	Linger        null.Bool `json:"linger" envconfig:"linger"`
-	NoUsageReport null.Bool `json:"noUsageReport" envconfig:"no_usage_report"`
-	NoThresholds  null.Bool `json:"noThresholds" envconfig:"no_thresholds"`
-	NoSummary     null.Bool `json:"noSummary" envconfig:"no_summary"`
+	Out           []string    `json:"out" envconfig:"out"`
+	Linger        null.Bool   `json:"linger" envconfig:"linger"`
+	NoUsageReport null.Bool   `json:"noUsageReport" envconfig:"no_usage_report"`
+	NoThresholds  null.Bool   `json:"noThresholds" envconfig:"no_thresholds"`
+	NoSummary     null.Bool   `json:"noSummary" envconfig:"no_summary"`
+	ReportSummary null.String `json:"reportSummary" envconfig:"report_summary"`
 
 	Collectors struct {
 		InfluxDB influxdb.Config `json:"influxdb"`
@@ -93,6 +96,9 @@ func (c Config) Apply(cfg Config) Config {
 	if cfg.NoSummary.Valid {
 		c.NoSummary = cfg.NoSummary
 	}
+	if cfg.ReportSummary.Valid {
+		c.ReportSummary = cfg.ReportSummary
+	}
 	c.Collectors.InfluxDB = c.Collectors.InfluxDB.Apply(cfg.Collectors.InfluxDB)
 	c.Collectors.Cloud = c.Collectors.Cloud.Apply(cfg.Collectors.Cloud)
 	c.Collectors.Kafka = c.Collectors.Kafka.Apply(cfg.Collectors.Kafka)
@@ -119,6 +125,7 @@ func getConfig(flags *pflag.FlagSet) (Config, error) {
 		NoUsageReport: getNullBool(flags, "no-usage-report"),
 		NoThresholds:  getNullBool(flags, "no-thresholds"),
 		NoSummary:     getNullBool(flags, "no-summary"),
+		ReportSummary: getNullString(flags, "report-summary"),
 	}, nil
 }
 

cmd/run.go

@@ -26,6 +26,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 	"os"
 	"os/signal"
@@ -455,9 +456,22 @@ a commandline interface for interacting with it.`,
 				Metrics: engine.Metrics,
 				Time:    engine.Executor.GetTime(),
 			}
-			// TODO: add json summary later
-			switch {
-			default:
+			if conf.ReportSummary.Valid {
+				var w io.Writer = stdout
+				if conf.ReportSummary.String != "" {
+					f, err := os.Create(conf.ReportSummary.String)
+					if err != nil {
+						panic(err)
+					}
+					w = f
+					defer func() {
+						if err := f.Close(); err != nil {
+							panic(err)
+						}
+					}()
+				}
+				ui.SummarizeJSON(w, data)
+			} else {
 				ui.Summarize(stdout, "", data)
 			}