Add Versioning support

BUILD.md

@@ -15,6 +15,43 @@ Now ready to modify the code and build two binaries, `cmd/gobgp` and `cmd/gobgpd
 
 GoBGP releases are time-based. Minor releases will occur every month ([Semantic Versioning](https://semver.org/)). Major releases occur only when absolutely necessary.
 
+## Versioning
+
+GoBGP has a internal module for version information.
+```internal/pkg/version/version.go``` defines the following variables
+
+```MAJOR``` ```MINOR``` ```PATCH``` these constants are for the Semantic Versioning scheme.
+These will be updated upon release by maintainer.
+
+There is also two more variables that are ment to be changed by ldflags;
+
+```TAG``` is supposed to be used to denote which branch the build is based upon.
+```SHA``` is supposed to be used to inform about which git sha sum the build is based on.
+
+### Examples
+
+A normal release version of GoBGP Version 2.5.0 should should have;
+
+```golang
+const MAJOR uint = 2
+const MINOR uint = 5
+const PATCH uint = 0
+```
+
+If you have a non-standard release and want to have more build information there is some flags to be used.
+`COMMIT`, `IDENTIFIER` and `METADATA`.
+
+```bash
+go build -ldflags \
+	"-X github.com/osrg/gobgp/internal/pkg/version.COMMIT=`git rev-parse --short HEAD` \
+	 -X github.com/osrg/gobgp/internal/pkg/version.METADATA="date.`date "+%Y%m%d"`" \
+	 -X github.com/osrg/gobgp/internal/pkg/version.IDENTIFIER=alpha"
+```
+
+This will produce a version number of
+
+```2.5.0-alpaha+commit.XXXYYYZZ.date.20190526```
+
 ## Layout
 
 The GoBGP project adopts [Standard Go Project Layout](https://github.com/golang-standards/project-layout).

cmd/gobgp/main.go

@@ -19,14 +19,13 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/osrg/gobgp/internal/pkg/version"
 	"google.golang.org/grpc"
 )
 
-var version = "master"
-
 func main() {
 	if len(os.Args) > 1 && os.Args[1] == "--version" {
-		fmt.Println("gobgp version", version)
+		fmt.Println("gobgp version", version.Version())
 		os.Exit(0)
 	}
 	grpc.EnableTracing = false

cmd/gobgpd/main.go

@@ -39,12 +39,11 @@ import (
 	"github.com/osrg/gobgp/internal/pkg/apiutil"
 	"github.com/osrg/gobgp/internal/pkg/config"
 	"github.com/osrg/gobgp/internal/pkg/table"
+	"github.com/osrg/gobgp/internal/pkg/version"
 	"github.com/osrg/gobgp/pkg/packet/bgp"
 	"github.com/osrg/gobgp/pkg/server"
 )
 
-var version = "master"
-
 func marshalRouteTargets(l []string) ([]*any.Any, error) {
 	rtList := make([]*any.Any, 0, len(l))
 	for _, rtString := range l {
@@ -132,7 +131,7 @@ func main() {
 	}
 
 	if opts.Version {
-		fmt.Println("gobgpd version", version)
+		fmt.Println("gobgpd version", version.Version())
 		os.Exit(0)
 	}
 

internal/pkg/version/version.go

@@ -0,0 +1,51 @@
+// Copyright (C) 2018 Nippon Telegraph and Telephone Corporation.
+//
+// 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
+//
+//    http://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
+
+import "fmt"
+
+const MAJOR uint = 2
+const MINOR uint = 5
+const PATCH uint = 0
+
+var COMMIT string = ""
+var IDENTIFIER string = ""
+var METADATA string = ""
+
+func Version() string {
+	var suffix string = ""
+	if len(IDENTIFIER) > 0 {
+		suffix = fmt.Sprintf("-%s", IDENTIFIER)
+	}
+
+	if len(COMMIT) > 0 || len(METADATA) > 0 {
+		suffix = suffix + "+"
+	}
+
+	if len(COMMIT) > 0 {
+		suffix = fmt.Sprintf("%s"+"commit.%s", suffix, COMMIT)
+
+	}
+
+	if len(METADATA) > 0 {
+		if len(COMMIT) > 0 {
+			suffix = suffix + "."
+		}
+		suffix = suffix + METADATA
+	}
+
+	return fmt.Sprintf("%d.%d.%d%s", MAJOR, MINOR, PATCH, suffix)
+}