add log levels support

Author: andfasano

cmd/node-joiner/main.go

@@ -1,9 +1,15 @@
 package main
 
 import (
+	"fmt"
+	"io"
+	"os"
+
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	terminal "golang.org/x/term"
 
+	"github.com/openshift/installer/cmd/openshift-install/command"
 	"github.com/openshift/installer/pkg/nodejoiner"
 )
 
@@ -33,14 +39,47 @@ func main() {
 	}
 
 	rootCmd := &cobra.Command{
-		Use: "node-joiner",
+		Use:              "node-joiner",
+		PersistentPreRun: runRootCmd,
 	}
 	rootCmd.PersistentFlags().String("kubeconfig", "", "Path to the kubeconfig file.")
 	rootCmd.PersistentFlags().String("dir", ".", "assets directory")
+	rootCmd.PersistentFlags().String("log-level", "info", "log level (e.g. \"debug | info | warn | error\")")
 
 	rootCmd.AddCommand(nodesAddCmd)
 	rootCmd.AddCommand(nodesMonitorCmd)
 	if err := rootCmd.Execute(); err != nil {
 		logrus.Fatal(err)
 	}
 }
+
+func runRootCmd(cmd *cobra.Command, args []string) {
+	logrus.SetOutput(io.Discard)
+	logrus.SetLevel(logrus.TraceLevel)
+
+	logLevel, err := cmd.Flags().GetString("log-level")
+	if err != nil {
+		logrus.Fatal(err)
+	}
+
+	level, err := logrus.ParseLevel(logLevel)
+	if err != nil {
+		level = logrus.InfoLevel
+	}
+
+	logrus.AddHook(command.NewFileHookWithNewlineTruncate(os.Stderr, level, &logrus.TextFormatter{
+		// Setting ForceColors is necessary because logrus.TextFormatter determines
+		// whether or not to enable colors by looking at the output of the logger.
+		// In this case, the output is io.Discard, which is not a terminal.
+		// Overriding it here allows the same check to be done, but against the
+		// hook's output instead of the logger's output.
+		ForceColors:            terminal.IsTerminal(int(os.Stderr.Fd())),
+		DisableTimestamp:       true,
+		DisableLevelTruncation: true,
+		DisableQuote:           true,
+	}))
+
+	if err != nil {
+		logrus.Fatal(fmt.Errorf("invalid log-level: %w", err))
+	}
+}