get default from envvar

cmd/root.go

@@ -29,7 +29,8 @@ func Execute() {
 		Run:   applyCommand.Execute,
 		Args:  cobra.MinimumNArgs(1),
 	}
-	applyCmd.Flags().StringVar(&applyCommand.Database, "database", "", "Database URL")
+
+	applyCmd.Flags().StringVar(&applyCommand.Database, "database", os.Getenv("DB_HOST"), "Database URL")
 	rootCmd.AddCommand(generateCmd)
 	rootCmd.AddCommand(applyCmd)
 

go.mod

@@ -2,10 +2,13 @@ module github.com/kenji-yamane/mgr8
 
 go 1.17
 
+require (
+	github.com/jmoiron/sqlx v1.3.4
+	github.com/lib/pq v1.10.4
+	github.com/spf13/cobra v1.4.0
+)
+
 require (
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
-	github.com/jmoiron/sqlx v1.3.4 // indirect
-	github.com/lib/pq v1.10.4 // indirect
-	github.com/spf13/cobra v1.4.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 )

go.sum

@@ -1,4 +1,5 @@
 github.com/cpuguy83/go-md2man/v2 v2.0.1/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/go-sql-driver/mysql v1.5.0 h1:ozyZYNQW3x3HtqT1jira07DN2PArx2v7/mN66gGcHOs=
 github.com/go-sql-driver/mysql v1.5.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
 github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
@@ -7,6 +8,7 @@ github.com/jmoiron/sqlx v1.3.4/go.mod h1:2BljVx/86SuTyjE+aPYlHCTNvZrnJXghYGpNiXL
 github.com/lib/pq v1.2.0/go.mod h1:5WUZQaWbwv1U+lTReE5YruASi9Al49XbQIvNi/34Woo=
 github.com/lib/pq v1.10.4 h1:SO9z7FRPzA03QhHKJrH5BXA6HU1rS4V2nIVrrNC1iYk=
 github.com/lib/pq v1.10.4/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
+github.com/mattn/go-sqlite3 v1.14.6 h1:dNPt6NO46WmLVt2DLNpwczCmdV5boIZ6g/tlDrlRUbg=
 github.com/mattn/go-sqlite3 v1.14.6/go.mod h1:NyWgC/yNuGj7Q9rpYnZvas74GogHl5/Z4A/KQRfk6bU=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/spf13/cobra v1.4.0 h1:y+wJpx64xcgO1V+RcnwW0LEHxTKRi2ZDPSBjWnrg88Q=