Move go version check into main() (#3734)

Previously the check was done in init().  This patch moves into main
for unit testable friendly function.

cmd/globals.go

@@ -31,11 +31,6 @@ import (
 	"github.com/minio/minio/pkg/objcache"
 )
 
-// Global constants for Minio.
-const (
-	minGoVersion = ">= 1.7" // Minio requires at least Go v1.7
-)
-
 // minio configuration related constants.
 const (
 	globalMinioConfigVersion      = "13"

cmd/main.go

@@ -65,12 +65,6 @@ VERSION:
   ` + Version +
 	`{{ "\n"}}`
 
-// init - check the environment before main starts
-func init() {
-	// Check if minio was compiled using a supported version of Golang.
-	checkGoVersion()
-}
-
 func migrate() {
 	// Migrate config file
 	err := migrateConfig()

cmd/runtime-checks.go

@@ -1,45 +0,0 @@
-/*
- * Minio Cloud Storage, (C) 2015, 2016 Minio, Inc.
- *
- * 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 cmd
-
-import (
-	"fmt"
-	"runtime"
-
-	"github.com/hashicorp/go-version"
-	"github.com/minio/mc/pkg/console"
-)
-
-// check if minimum Go version is met.
-func checkGoVersion() {
-	// Current version.
-	curVersion, e := version.NewVersion(runtime.Version()[2:])
-	if e != nil {
-		console.Fatalln("Unable to determine current go version.", e)
-	}
-
-	// Prepare version constraint.
-	constraints, e := version.NewConstraint(minGoVersion)
-	if e != nil {
-		console.Fatalln("Unable to check go version.")
-	}
-
-	// Check for minimum version.
-	if !constraints.Check(curVersion) {
-		console.Fatalln(fmt.Sprintf("Please recompile Minio with Golang version %s.", minGoVersion))
-	}
-}