feat: support to send the metrics to prometheus

Experimental support to send the performance metrics to the prometheus,
powerred by the k6 plugin xk6-output-prometheus-remote.

Signed-off-by: chlins <[email protected]>

README.md

@@ -37,7 +37,7 @@ Then:
   go run mage.go
   ```
 
-## The environment variables  and targets
+## The environment variables and targets
 
 The environment variables in the table are the configurations for the performance testing. Use `VAR1=value1 VAR2=value2 go run mage.go target` format to apply the variables to the testing
 
@@ -53,6 +53,16 @@ The environment variables in the table are the configurations for the performanc
 | K6_JSON_OUTPUT    | Make k6 output detailed statistics in JSON format            | false         |
 | HARBOR_REPORT     | Whether generate testing report                              | false         |
 
+**Experimental** to send the metrics to the prometheus. (Refer to <https://k6.io/docs/results-output/real-time/prometheus-remote-write> for more details)
+| Variable          | Description                                                  | Default value |
+| ----------------- | ------------------------------------------------------------ | ------------- |
+| K6_PROMETHEUS_RW_SERVER_URL | URL of the Prometheus remote write implementation's endpoint |     |
+| K6_PROMETHEUS_RW_USERNAME | User for the HTTP Basic authentication at the Prometheus remote write endpoint | |
+| K6_PROMETHEUS_RW_PASSWORD |  Password for the HTTP Basic authentication at the Prometheus remote write endpoint| |
+| K6_PROMETHEUS_RW_TREND_AS_NATIVE_HISTOGRAM | If true, it maps the all defined trend metrics as Native Histograms | false |
+| K6_PROMETHEUS_RW_TREND_STATS | It's a comma-separated list of stats functions | min,p(90),p(95),p(99),max |
+| K6_PROMETHEUS_RW_INSECURE_SKIP_TLS_VERIFY | If true, the HTTP client skips TLS verification on the endpoint | false |
+
 
 The following table includes the targets.
 

magefile.go

@@ -34,6 +34,15 @@ const (
 
 	K6CsvOutputEnvKey  = "K6_CSV_OUTPUT"
 	K6JsonOutputEnvKey = "K6_JSON_OUTPUT"
+
+	// xk6-output-prometheus-remote related configurations
+	K6Out                                = "K6_OUT"
+	K6PrometheusRwInsecureSkipTlsVerify  = "K6_PROMETHEUS_RW_INSECURE_SKIP_TLS_VERIFY"
+	K6PrometheusRwServerURL              = "K6_PROMETHEUS_RW_SERVER_URL"
+	K6PrometheusRwUsername               = "K6_PROMETHEUS_RW_USERNAME"
+	K6PrometheusRwPassword               = "K6_PROMETHEUS_RW_PASSWORD"
+	K6PrometheusRwTrendAsNativeHistogram = "K6_PROMETHEUS_RW_TREND_AS_NATIVE_HISTOGRAM"
+	K6PrometheusRwTrendStats             = "K6_PROMETHEUS_RW_TREND_STATS"
 )
 
 // Default target to run when none is specified
@@ -226,6 +235,34 @@ func addHarborEnv(env map[string]string) map[string]string {
 		env["HARBOR_PASSWORD"], _ = u.User.Password()
 	}
 
+	// send metrics to prometheus
+	if promURL := os.Getenv(K6PrometheusRwServerURL); promURL != "" {
+		env[K6PrometheusRwServerURL] = promURL
+		env[K6Out] = "xk6-prometheus-rw"
+
+		if username := os.Getenv(K6PrometheusRwUsername); username != "" {
+			env[K6PrometheusRwUsername] = username
+		}
+		if password := os.Getenv(K6PrometheusRwPassword); password != "" {
+			env[K6PrometheusRwPassword] = password
+		}
+
+		if getEnvBool(K6PrometheusRwTrendAsNativeHistogram) {
+			env[K6PrometheusRwTrendAsNativeHistogram] = "true"
+		}
+
+		if getEnvBool(K6PrometheusRwInsecureSkipTlsVerify) {
+			env[K6PrometheusRwInsecureSkipTlsVerify] = "true"
+		}
+
+		if stats := os.Getenv(K6PrometheusRwTrendStats); stats != "" {
+			env[K6PrometheusRwTrendStats] = stats
+		} else {
+			// set the following trend stats by default
+			env[K6PrometheusRwTrendStats] = "min,p(90),p(95),p(99),max"
+		}
+	}
+
 	return env
 }
 
@@ -271,6 +308,19 @@ func getK6RunArgs(script string) []string {
 	if hasOutputs {
 		args = append(args, "--tag", fmt.Sprintf("script=%s", scriptName))
 	}
+	// append testid as tag if send metrics to prometheus
+	if os.Getenv(K6PrometheusRwServerURL) != "" {
+		size := os.Getenv(HarborSizeEnvKey)
+		vus := os.Getenv(HarborVusEnvKey)
+		if vus == "" {
+			// the default VUS in script is 500 if user not specified
+			vus = "500"
+		}
+		// these tags will be the custom label for prom metrics
+		args = append(args, "--tag", fmt.Sprintf("testid=%s", scriptName))
+		args = append(args, "--tag", fmt.Sprintf("size=%s", size))
+		args = append(args, "--tag", fmt.Sprintf("vus=%s", vus))
+	}
 
 	return args
 }