support structs with default values (#1)

* support struct with default values #183
* omit space

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/brotherpowers/ipsubnet v0.0.0-20170914094241-30bc98f0a5b1
 	github.com/containers/image/v5 v5.7.0
 	github.com/containers/storage v1.30.0
+	github.com/creasty/defaults v1.5.2
 	github.com/manifoldco/promptui v0.8.0
 	github.com/opencontainers/image-spec v1.0.2-0.20190823105129-775207bd45b6
 	github.com/opencontainers/umoci v0.4.6

go.sum

@@ -212,6 +212,8 @@ github.com/cpuguy83/go-md2man/v2 v2.0.0 h1:EoUDS0afbrsXAZ9YQ9jdu/mZ2sXgT1/2yyNng
 github.com/cpuguy83/go-md2man/v2 v2.0.0/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/creasty/defaults v1.5.2 h1:/VfB6uxpyp6h0fr7SPp7n8WJBoV8jfxQXPCnkVSjyls=
+github.com/creasty/defaults v1.5.2/go.mod h1:FPZ+Y0WNrbqOVw+c6av63eyHUAl6pMHZwqLPvXUZGfY=
 github.com/cyphar/filepath-securejoin v0.2.2 h1:jCwT2GTP+PY5nBz3c/YL5PAIbusElVrPujOBSCj8xRg=
 github.com/cyphar/filepath-securejoin v0.2.2/go.mod h1:FpkQEhXnPnOthhzymB7CGsFk2G9VLXONKD9G7QGMM+4=
 github.com/d2g/dhcp4 v0.0.0-20170904100407-a1d1b6c41b1c/go.mod h1:Ct2BUK8SB0YC1SMSibvLzxjeJLnrYEVLULFNiHY9YfQ=

internal/pkg/warewulfconf/datastructure.go

@@ -3,6 +3,7 @@ package warewulfconf
 import (
 	"github.com/hpcng/warewulf/internal/pkg/util"
 	"github.com/hpcng/warewulf/internal/pkg/wwlog"
+	"github.com/creasty/defaults"
 )
 
 const ConfigFile = "/etc/warewulf/warewulf.conf"
@@ -43,12 +44,23 @@ type TftpConf struct {
 }
 
 type NfsConf struct {
-	Enabled     bool     `yaml:"enabled"`
+	Enabled     bool     `default:"true" yaml:"enabled"`
 	Exports     []string `yaml:"exports"`
 	ExportsExtended []*NfsExportConf `yaml:"exports extended"`
 	SystemdName string   `yaml:"systemd name"`
 }
 
+func (s *NfsConf) UnmarshalYAML(unmarshal func(interface{}) error) error {
+    defaults.Set(s)
+
+    type plain NfsConf
+    if err := unmarshal((*plain)(s)); err != nil {
+        return err
+    }
+
+    return nil
+}
+
 type NfsExportConf struct {
 	Path     string  `yaml:"path"`
 	Options  string  `yaml:"options"`