move version to package

Makefile

@@ -37,7 +37,7 @@ build:
 	go build
 
 build_static:
-	go build --ldflags '-extldflags "-static" -X main.build=$(CI_BUILD_NUMBER)' -o drone_static
+	go build --ldflags '-extldflags "-static" -X github.com/drone/drone/version.VersionDev=$(CI_BUILD_NUMBER)' -o drone_static
 
 test:
 	go test -cover $(PACKAGES)

drone.go

@@ -16,10 +16,6 @@ import (
 	"github.com/Sirupsen/logrus"
 )
 
-// build revision number populated by the continuous
-// integration server at compile time.
-var build string = "custom"
-
 var (
 	dotenv = flag.String("config", ".env", "")
 	debug  = flag.Bool("debug", false, "")
@@ -49,7 +45,7 @@ func main() {
 	server_ := server.Load(env)
 	server_.Run(
 		router.Load(
-			header.Version(build),
+			header.Version,
 			cache.Default(),
 			context.SetStore(store_),
 			context.SetRemote(remote_),

router/middleware/header/header.go

@@ -4,11 +4,10 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/drone/drone/version"
 	"github.com/gin-gonic/gin"
 )
 
-var version string
-
 // NoCache is a middleware function that appends headers
 // to prevent the client from caching the HTTP response.
 func NoCache(c *gin.Context) {
@@ -52,10 +51,7 @@ func Secure(c *gin.Context) {
 // Version is a middleware function that appends the Drone
 // version information to the HTTP response. This is intended
 // for debugging and troubleshooting.
-func Version(version string) gin.HandlerFunc {
-	return func(c *gin.Context) {
-		c.Set("version", "0.4.0-beta+"+version)
-		c.Header("X-DRONE-VERSION", "0.4.0-beta+"+version)
+func Version(c *gin.Context) {
+	c.Header("X-DRONE-VERSION", version.Version)
 	c.Next()
-	}
 }

version/version.go

@@ -0,0 +1,19 @@
+package version
+
+import "fmt"
+
+const (
+	// VersionMajor is for an API incompatible changes
+	VersionMajor = 0
+	// VersionMinor is for functionality in a backwards-compatible manner
+	VersionMinor = 4
+	// VersionPatch is for backwards-compatible bug fixes
+	VersionPatch = 1
+
+	// VersionDev indicates development branch. Releases will be empty string.
+	VersionDev = "dev"
+)
+
+// Version is the specification version that the package types support.
+var Version = fmt.Sprintf("%d.%d.%d+%s",
+	VersionMajor, VersionMinor, VersionPatch, VersionDev)