Drop k6's debug output from logs pushed to Loki

This is not really helping the user debug anything. If we need to, we
can send it to our own instance, as it's more relevant to us that it's
to the user.

Signed-off-by: Marcelo E. Magallon <[email protected]>

internal/k6runner/k6runner.go

@@ -181,12 +181,23 @@ func k6LogsToLogger(logs []byte, logger logger.Logger) error {
 	// labels.
 	dec := logfmt.NewDecoder(bytes.NewBuffer(logs))
 
+NEXT_RECORD:
 	for dec.ScanRecord() {
 		var line []interface{}
+		var source, level string
 		for dec.ScanKeyval() {
-			key := dec.Key()
-			value := dec.Value()
-			line = append(line, string(key), string(value))
+			key := string(dec.Key())
+			value := string(dec.Value())
+			switch key {
+			case "source":
+				source = value
+			case "level":
+				level = value
+			}
+			line = append(line, key, value)
+		}
+		if level == "debug" && source == "" { // if there's no source, it's probably coming from k6
+			continue NEXT_RECORD
 		}
 		_ = logger.Log(line...)
 	}

internal/prober/multihttp/script_test.go

@@ -4,10 +4,12 @@ import (
 	"bytes"
 	"context"
 	"net/http/httptest"
+	"path/filepath"
 	"strings"
 	"testing"
 
 	kitlog "github.com/go-kit/kit/log" //nolint:staticcheck // TODO(mem): replace in BBE
+	"github.com/go-kit/log/level"
 	"github.com/grafana/synthetic-monitoring-agent/internal/k6runner"
 	"github.com/grafana/synthetic-monitoring-agent/internal/testhelper"
 	sm "github.com/grafana/synthetic-monitoring-agent/pkg/pb/synthetic_monitoring"
@@ -755,23 +757,34 @@ func TestSettingsToScript(t *testing.T) {
 	require.NotEmpty(t, actual)
 
 	check := sm.Check{
+		Target: settings.Entries[0].Request.Url,
+		Job:    "test",
 		Settings: sm.CheckSettings{
 			Multihttp: settings,
 		},
 	}
 
 	ctx, cancel := testhelper.Context(context.Background(), t)
 	t.Cleanup(cancel)
-	logger := zerolog.New(zerolog.NewTestWriter(t))
-	runner := k6runner.New("k6")
+	// logger := zerolog.New(zerolog.NewTestWriter(t))
+	logger := zerolog.Nop()
+	k6path := filepath.Join(testhelper.ModuleDir(t), "dist", "k6")
+	runner := k6runner.New(k6path)
 
 	prober, err := NewProber(ctx, check, logger, runner)
 	require.NoError(t, err)
 
 	reg := prometheus.NewPedanticRegistry()
+	require.NotNil(t, reg)
+
 	var buf bytes.Buffer
-	plogger := kitlog.NewLogfmtLogger(&buf)
-	prober.Probe(ctx, "foo", reg, plogger)
+	userLogger := level.NewFilter(kitlog.NewLogfmtLogger(&buf), level.AllowInfo(), level.SquelchNoLevel(false))
+	require.NotNil(t, userLogger)
+
+	success := prober.Probe(ctx, check.Target, reg, userLogger)
+	require.True(t, success)
+
+	t.Log(buf.String())
 }
 
 func TestReplaceVariablesInString(t *testing.T) {

internal/testhelper/testhelper.go

@@ -3,6 +3,8 @@ package testhelper
 import (
 	"context"
 	"os"
+	"path/filepath"
+	"runtime"
 	"testing"
 	"time"
 
@@ -27,3 +29,29 @@ func MustReadFile(t *testing.T, filename string) []byte {
 
 	return data
 }
+
+func ModuleDir(t *testing.T) string {
+	t.Helper()
+
+	_, filename, _, ok := runtime.Caller(1)
+	if !ok {
+		// uh?
+		return ""
+	}
+	dir := filepath.Dir(filename)
+	for dir != "/" {
+		gomod := filepath.Join(dir, "go.mod")
+		_, err := os.Stat(gomod)
+		switch {
+		case err == nil:
+			return dir
+		case os.IsNotExist(err):
+			dir = filepath.Join(dir, "..")
+			continue
+		default:
+			panic(err)
+		}
+	}
+
+	return dir
+}

xk6/sm/output.go

@@ -15,8 +15,10 @@ import (
 	"go.k6.io/k6/output"
 )
 
+const ExtensionName = "sm"
+
 func init() {
-	output.RegisterExtension("sm", New)
+	output.RegisterExtension(ExtensionName, New)
 }
 
 // Output is a k6 output plugin that writes metrics to an io.Writer in
@@ -118,6 +120,7 @@ func (o *Output) Stop() error {
 				// might end up with invalid label values. This is probably a job for Loki,
 				// meaning we need an structured way of storing this information in logs.
 				fields := logrus.Fields{
+					"source":   ExtensionName,
 					"metric":   metricName,
 					"scenario": scenario,
 					"value":    value,