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

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

Makefile

@@ -107,6 +107,7 @@ spelling:
 
 test: build
 	@echo "Running all minio testing:"
+	@go test $(GOFLAGS) .
 	@go test $(GOFLAGS) github.com/minio/minio/cmd...
 	@go test $(GOFLAGS) github.com/minio/minio/pkg...
 

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))
-	}
-}

main.go

@@ -1,5 +1,5 @@
 /*
- * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ * Minio Cloud Storage, (C) 2016,2017 Minio, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,11 +23,47 @@
 package main // import "github.com/minio/minio"
 
 import (
+	"fmt"
 	"os"
+	"runtime"
 
+	version "github.com/hashicorp/go-version"
+	"github.com/minio/mc/pkg/console"
 	minio "github.com/minio/minio/cmd"
 )
 
+const (
+	// Minio requires at least Go v1.7
+	minGoVersion        = "1.7"
+	goVersionConstraint = ">= " + minGoVersion
+)
+
+// Check if this binary is compiled with at least minimum Go version.
+func checkGoVersion(goVersionStr string) error {
+	constraint, err := version.NewConstraint(goVersionConstraint)
+	if err != nil {
+		return fmt.Errorf("'%s': %s", goVersionConstraint, err)
+	}
+
+	goVersion, err := version.NewVersion(goVersionStr)
+	if err != nil {
+		return err
+	}
+
+	if !constraint.Check(goVersion) {
+		return fmt.Errorf("Minio is not compiled by Go %s.  Please recompile accordingly.",
+			goVersionConstraint)
+	}
+
+	return nil
+}
+
 func main() {
+	// When `go get` is used minimum Go version check is not triggered but it would have compiled it successfully.
+	// However such binary will fail at runtime, hence we also check Go version at runtime.
+	if err := checkGoVersion(runtime.Version()[2:]); err != nil {
+		console.Fatalln("Go runtime version check failed.", err)
+	}
+
 	minio.Main(os.Args, os.Exit)
 }

main_test.go

@@ -0,0 +1,50 @@
+/*
+ * Minio Cloud Storage, (C) 2017 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 main
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestCheckGoVersion(t *testing.T) {
+	// Test success cases.
+	testCases := []struct {
+		version     string
+		expectedErr error
+	}{
+		{minGoVersion, nil},
+		{minGoVersion + ".10", nil},
+		{"1.6.8", fmt.Errorf("Minio is not compiled by Go >= 1.7.  Please recompile accordingly.")},
+		{"0.1", fmt.Errorf("Minio is not compiled by Go >= 1.7.  Please recompile accordingly.")},
+		{".1", fmt.Errorf("Malformed version: .1")},
+		{"somejunk", fmt.Errorf("Malformed version: somejunk")},
+	}
+
+	for _, testCase := range testCases {
+		err := checkGoVersion(testCase.version)
+		if testCase.expectedErr == nil {
+			if err != nil {
+				t.Fatalf("expected: %v, got: %v", testCase.expectedErr, err)
+			}
+		} else if err == nil {
+			t.Fatalf("expected: %v, got: %v", testCase.expectedErr, err)
+		} else if testCase.expectedErr.Error() != err.Error() {
+			t.Fatalf("expected: %v, got: %v", testCase.expectedErr, err)
+		}
+	}
+}