adding ability to write a log file with all output from collector. Executing commands will now log be logged (and when debug is enabled, their output's are also logged).

collector/cmd/collector-selftest/collector-selftest.go

@@ -5,6 +5,7 @@ import (
 	"github.com/analogj/scrutiny/collector/pkg/collector"
 	"github.com/analogj/scrutiny/webapp/backend/pkg/version"
 	"github.com/sirupsen/logrus"
+	"io"
 	"log"
 	"os"
 	"time"
@@ -85,6 +86,16 @@ OPTIONS:
 						logrus.SetLevel(logrus.InfoLevel)
 					}
 
+					if c.IsSet("log-file") {
+						logFile, err := os.OpenFile(c.String("log-file"), os.O_CREATE|os.O_WRONLY, 0644)
+						if err != nil {
+							logrus.Errorf("Failed to open log file %s for output: %s", c.String("log-file"), err)
+							return err
+						}
+						defer logFile.Close()
+						logrus.SetOutput(io.MultiWriter(os.Stderr, logFile))
+					}
+
 					stCollector, err := collector.CreateSelfTestCollector(
 						collectorLogger,
 						c.String("api-endpoint"),
@@ -105,6 +116,12 @@ OPTIONS:
 						EnvVars: []string{"SCRUTINY_API_ENDPOINT"},
 					},
 
+					&cli.StringFlag{
+						Name:  "log-file",
+						Usage: "Path to file for logging. Leave empty to use STDOUT",
+						Value: "",
+					},
+
 					&cli.BoolFlag{
 						Name:    "debug",
 						Usage:   "Enable debug logging",