[#204] Refactoring for version cmd

Now the version can be changed from Makefile/env.
By default version is 'devel' if there is no ldflags in build args.
It can be overriden by providing ldflags in Makefile.

Change-Id: Ifef5932ec953ccfaeca8a2ef58eb951c900c7a59

Makefile

@@ -1,6 +1,10 @@
 SHELL := /bin/bash
 
+GIT_VERSION         ?= v0.1.0
+GIT_MODULE          ?= opendev.org/airship/airshipctl/pkg/version
+
 GO_FLAGS            := -ldflags '-extldflags "-static"' -tags=netgo
+GO_FLAGS            += -ldflags "-X ${GIT_MODULE}.gitVersion=${GIT_VERSION}"
 
 BINDIR              := bin
 EXECUTABLE_CLI      := airshipctl

cmd/testdata/TestVersionGoldenOutput/version.golden

@@ -1 +1 @@
-airshipctl:   v0.1.0
+airshipctl:   devel

cmd/version.go

@@ -20,9 +20,10 @@ import (
 	"github.com/spf13/cobra"
 
 	"opendev.org/airship/airshipctl/pkg/util"
+	"opendev.org/airship/airshipctl/pkg/version"
 )
 
-// NewVersionCommand creates a command for displaying the version of airshipctl.
+// NewVersionCommand creates a command for displaying the version of airshipctl
 func NewVersionCommand() *cobra.Command {
 	versionCmd := &cobra.Command{
 		Use:   "version",
@@ -39,6 +40,6 @@ func NewVersionCommand() *cobra.Command {
 }
 
 func clientVersion() string {
-	// TODO(howell): There's gotta be a smarter way to do this
-	return "v0.1.0"
+	v := version.Get()
+	return v.GitVersion
 }

pkg/version/version.go

@@ -0,0 +1,35 @@
+/*
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     https://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+package version
+
+var (
+	gitVersion = "devel"
+)
+
+// Info structure provides version data for airshipctl
+// For now it has GitVersion with format 'v0.1.0'
+// provided from Makefile during building airshipctl
+// or defined in a local var for development purposes
+type Info struct {
+	GitVersion string `json:"gitVersion"`
+}
+
+// Get function shows airshipctl version
+// returns filled Info structure
+func Get() Info {
+	return Info{
+		GitVersion: gitVersion,
+	}
+}