register default only when terminal (#40)

Author: Dean Karn

go.mod

@@ -5,4 +5,7 @@ go 1.18
 require (
 	github.com/go-playground/errors/v5 v5.2.2
 	github.com/go-playground/pkg/v5 v5.6.0
+	golang.org/x/term v0.0.0-20220526004731-065cf7ba2467
 )
+
+require golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1 // indirect

go.sum

@@ -2,3 +2,7 @@ github.com/go-playground/errors/v5 v5.2.2 h1:1C8GMFeObklONQn7v7Y09kTrNgibvbS3+eJ
 github.com/go-playground/errors/v5 v5.2.2/go.mod h1:DincxRGwraWmq39TZDqtnOtHGOJ+AbNbO0OmBzX6MLw=
 github.com/go-playground/pkg/v5 v5.6.0 h1:97YpRFzIcS5NFP2Uzxj8cPYz4zTuwweyXADYcA1KfUQ=
 github.com/go-playground/pkg/v5 v5.6.0/go.mod h1:TvZ2nNtNh6VfoNteY9ApA2BXt1ZwJliFZ4hzPAwLS9Y=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1 h1:SrN+KX8Art/Sf4HNj6Zcz06G7VEz+7w9tdXTPOZ7+l4=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20220526004731-065cf7ba2467 h1:CBpWXWQpIRjzmkkA+M7q9Fqnwd2mZr3AFqexg8YTfoM=
+golang.org/x/term v0.0.0-20220526004731-065cf7ba2467/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=

log.go

@@ -5,6 +5,8 @@ import (
 	"os"
 	"sync"
 	"time"
+
+	"golang.org/x/term"
 )
 
 var (
@@ -19,9 +21,11 @@ var (
 )
 
 func init() {
-	h := NewBuilder().Build()
-	AddHandler(h, AllLevels...)
-	defaultHandler = h
+	if term.IsTerminal(int(os.Stdin.Fd())) {
+		h := NewBuilder().Build()
+		AddHandler(h, AllLevels...)
+		defaultHandler = h
+	}
 }
 
 const (