Add version command and tag major-version-latest docker images (#21)

Fixes #20

.goreleaser.yml

@@ -1,6 +1,9 @@
 builds:
-- env:
-  - CGO_ENABLED=0
+  - binary: klein
+    env:
+      - CGO_ENABLED=0
+    ldflags:
+      - -s -w -X "github.com/kamaln7/klein/cmd.Version={{.Version}}"
 archive:
   replacements:
     darwin: Darwin
@@ -9,19 +12,20 @@ archive:
     386: i386
     amd64: x86_64
 checksum:
-  name_template: 'checksums.txt'
+  name_template: "checksums.txt"
 snapshot:
-  name_template: "{{ .Tag }}-next"
+  name_template: "{{ .Version }}-next"
 changelog:
   sort: asc
   filters:
     exclude:
-    - '^docs:'
-    - '^test:'
+      - "^docs:"
+      - "^test:"
 dockers:
   - dockerfile: Dockerfile-goreleaser
     extra_files:
       - 404.html
     image_templates:
       - "kamaln7/klein:{{ .Version }}"
+      - "kamaln7/klein:{{ .Major }}-latest"
       - kamaln7/klein:latest

cmd/version.go

@@ -0,0 +1,24 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(versionCmd)
+}
+
+// Version is the klein package version
+// to be filled in at compile time using ldflags
+var Version = "-dev"
+
+var versionCmd = &cobra.Command{
+	Use:   "version",
+	Short: "print the version number of klein",
+	Long:  "print the version number of klein",
+	Run: func(cmd *cobra.Command, args []string) {
+		fmt.Printf("klein v%s\n", Version)
+	},
+}