[#188] logging: Allow to print date in log messages

`timeonly`:
```
INFO[14:05:21] kek                                           endpoint=1
```

`datetime`:
```
INFO[2025-01-10 14:03:58] kek                                           endpoint=1
```

`none`
```
INFO kek                                           endpoint=1
```

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

internal/logging/logging.go

@@ -1,6 +1,8 @@
 package logging
 
 import (
+	"fmt"
+	"strings"
 	"time"
 
 	"github.com/dop251/goja"
@@ -57,14 +59,29 @@ func (r *RootModule) NewModuleInstance(vu modules.VU) modules.Instance {
 		return &Logging{vu: vu}
 	}
 
+	tsFormat, disableTs := time.TimeOnly, false
+	if val, ok := vu.InitEnv().LookupEnv("DATE_FORMAT"); ok {
+		switch strings.ToLower(val) {
+		case "timeonly":
+		case "datetime":
+			tsFormat = time.DateTime
+		case "none":
+			disableTs = true
+		default:
+			panic(fmt.Sprintf("invalid value for DATE_FORMAT: %s (should be `timeonly`, `datetime` or `none`)", val))
+		}
+	}
+
 	format := lg.Formatter
 	switch f := format.(type) {
 	case *logrus.TextFormatter:
 		f.ForceColors = true
 		f.FullTimestamp = true
-		f.TimestampFormat = time.TimeOnly
+		f.TimestampFormat = tsFormat
+		f.DisableTimestamp = disableTs
 	case *logrus.JSONFormatter:
-		f.TimestampFormat = time.TimeOnly
+		f.TimestampFormat = tsFormat
+		f.DisableTimestamp = disableTs
 	}
 
 	return &Logging{vu: vu}

scenarios/run_scenarios.md

@@ -21,6 +21,7 @@ Scenarios `grpc.js`, `local.js`, `http.js` and `s3.js` support the following opt
   * `PAYLOAD_TYPE` - type of an object payload ("random" or "text", default: "random").
   * `STREAMING` - if set, the payload is generated on the fly and is not read into memory fully.
   * `METRIC_TAGS` - custom metrics tags (format `tag1:value1;tag2:value2`).
+  * `DATE_FORMAT` - custom datetime format: `timeonly` (default), `datetime` or `none`.
 
 Additionally, the profiling extension can be enabled to generate CPU and memory profiles which can be inspected with `go tool pprof file.prof`:
 ```shell