Read the value of logger output path from environment variable if set (#293)

* Read the value of logger output path from environment variable if set

* Added lowercase check for logstream value

Author: abhide-tibco

support/log/logger.go

@@ -32,6 +32,7 @@ const (
 
 	EnvKeyLogSeparator  = "FLOGO_LOG_SEPARATOR"
 	DefaultLogSeparator = "\t"
+	EnvLogConsoleStream = "FLOGO_LOG_CONSOLE_STREAM"
 )
 
 type Level int

support/log/zap.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
+	"os"
+	"strings"
 )
 
 var traceLogger *zap.SugaredLogger
@@ -158,8 +160,15 @@ func newZapLogger(logFormat Format, level Level) (*zap.Logger, *zap.AtomicLevel,
 	cfg := zap.NewProductionConfig()
 	cfg.DisableCaller = true
 
-	cfg.OutputPaths = []string{"stdout"}
-	
+	// change the default output paths for the logger if the env variable is set and has the supported values (stderr and stdout).
+	// Otherwise, the logger will use the default value of stderr.
+	logstream, ok := os.LookupEnv(EnvLogConsoleStream)
+	if ok {
+		if strings.ToLower(logstream) == "stdout" || strings.ToLower(logstream) == "stderr" {
+			cfg.OutputPaths = []string{strings.ToLower(logstream)}
+		}
+	}
+
 	eCfg := cfg.EncoderConfig
 	eCfg.TimeKey = "timestamp"
 	eCfg.EncodeTime = zapcore.ISO8601TimeEncoder