From ab49498fc3b46d420b65e12a2aa5670999330070 Mon Sep 17 00:00:00 2001
From: Krishnan Parthasarathi <krisis@users.noreply.github.com>
Date: Wed, 14 Dec 2016 00:48:31 +0530
Subject: [PATCH] server: Exit gracefully if no endpoint is local to it.
 (#3442)

---
 cmd/server-main.go      | 18 ++++++++++++++++++
 cmd/server-main_test.go | 29 +++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/cmd/server-main.go b/cmd/server-main.go
index bb45b459d..04b3ac667 100644
--- a/cmd/server-main.go
+++ b/cmd/server-main.go
@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"net"
@@ -360,6 +361,18 @@ func checkServerSyntax(c *cli.Context) {
 	}
 }
 
+// Checks if any of the endpoints supplied is local to a server instance.
+func isAnyEndpointLocal(eps []*url.URL) bool {
+	anyLocalEp := false
+	for _, ep := range eps {
+		if isLocalStorage(ep) {
+			anyLocalEp = true
+			break
+		}
+	}
+	return anyLocalEp
+}
+
 // serverMain handler called for 'minio server' command.
 func serverMain(c *cli.Context) {
 	if !c.Args().Present() || c.Args().First() == "help" {
@@ -401,6 +414,11 @@ func serverMain(c *cli.Context) {
 	endpoints, err := parseStorageEndpoints(c.Args())
 	fatalIf(err, "Unable to parse storage endpoints %s", c.Args())
 
+	// Should exit gracefully if none of the endpoints passed as command line argument is local to this server.
+	if !isAnyEndpointLocal(endpoints) {
+		fatalIf(errors.New("No endpoint is local to this server"), "None of the disks supplied are local to this instance. Please check the disks supplied.")
+	}
+
 	storageDisks, err := initStorageDisks(endpoints)
 	fatalIf(err, "Unable to initialize storage disk(s).")
 
diff --git a/cmd/server-main_test.go b/cmd/server-main_test.go
index 4d0463971..1f6a1997f 100644
--- a/cmd/server-main_test.go
+++ b/cmd/server-main_test.go
@@ -347,3 +347,32 @@ func TestInitServerConfig(t *testing.T) {
 		initServerConfig(ctx)
 	}
 }
+
+// Tests isAnyEndpointLocal function with inputs such that it returns true and false respectively.
+func TestIsAnyEndpointLocal(t *testing.T) {
+	testCases := []struct {
+		disks  []string
+		result bool
+	}{
+		{
+			disks: []string{"http://4.4.4.4/mnt/disk1",
+				"http://4.4.4.4/mnt/disk1"},
+			result: false,
+		},
+		{
+			disks: []string{"http://localhost/mnt/disk1",
+				"http://localhost/mnt/disk1"},
+			result: true,
+		},
+	}
+	for i, test := range testCases {
+		endpoints, err := parseStorageEndpoints(test.disks)
+		if err != nil {
+			t.Fatalf("Test %d - Failed to parse storage endpoints %v", i+1, err)
+		}
+		actual := isAnyEndpointLocal(endpoints)
+		if actual != test.result {
+			t.Errorf("Test %d - Expected %v but received %v", i+1, test.result, actual)
+		}
+	}
+}