From 0f9e125cf3eb259709380e9847ac4e442480d082 Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Thu, 19 Nov 2020 10:38:02 -0800
Subject: [PATCH] fix: check for gateway backend online without http request
 (#10924)

fixes #10921
---
 cmd/gateway-common.go              | 20 +++++++-------------
 cmd/gateway/azure/gateway-azure.go | 10 +++++++---
 cmd/gateway/gcs/gateway-gcs.go     |  2 +-
 cmd/gateway/s3/gateway-s3.go       |  6 +++++-
 4 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/cmd/gateway-common.go b/cmd/gateway-common.go
index 492a803d7..93f6a2caa 100644
--- a/cmd/gateway-common.go
+++ b/cmd/gateway-common.go
@@ -18,6 +18,7 @@ package cmd
 
 import (
 	"context"
+	"net"
 	"net/http"
 	"strings"
 	"time"
@@ -254,25 +255,18 @@ func ToMinioClientCompleteParts(parts []CompletePart) []minio.CompletePart {
 // IsBackendOnline - verifies if the backend is reachable
 // by performing a GET request on the URL. returns 'true'
 // if backend is reachable.
-func IsBackendOnline(ctx context.Context, clnt *http.Client, urlStr string) bool {
+func IsBackendOnline(ctx context.Context, host string) bool {
+	var d net.Dialer
+
 	ctx, cancel := context.WithTimeout(ctx, 1*time.Second)
 	defer cancel()
 
-	// never follow redirects
-	clnt.CheckRedirect = func(*http.Request, []*http.Request) error {
-		return http.ErrUseLastResponse
-	}
-
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, urlStr, nil)
+	conn, err := d.DialContext(ctx, "tcp", host)
 	if err != nil {
 		return false
 	}
-	resp, err := clnt.Do(req)
-	if err != nil {
-		clnt.CloseIdleConnections()
-		return !xnet.IsNetworkOrHostDown(err, false)
-	}
-	xhttp.DrainBody(resp.Body)
+
+	conn.Close()
 	return true
 }
 
diff --git a/cmd/gateway/azure/gateway-azure.go b/cmd/gateway/azure/gateway-azure.go
index 7ce30ac01..eeee5ef4c 100644
--- a/cmd/gateway/azure/gateway-azure.go
+++ b/cmd/gateway/azure/gateway-azure.go
@@ -212,7 +212,7 @@ func (g *Azure) NewGatewayLayer(creds auth.Credentials) (minio.ObjectLayer, erro
 	client := azblob.NewServiceURL(*endpointURL, pipeline)
 
 	return &azureObjects{
-		endpoint:   endpointURL.String(),
+		endpoint:   endpointURL,
 		httpClient: httpClient,
 		client:     client,
 		metrics:    metrics,
@@ -424,7 +424,7 @@ func azurePropertiesToS3Meta(meta azblob.Metadata, props azblob.BlobHTTPHeaders,
 // azureObjects - Implements Object layer for Azure blob storage.
 type azureObjects struct {
 	minio.GatewayUnsupported
-	endpoint   string
+	endpoint   *url.URL
 	httpClient *http.Client
 	metrics    *minio.Metrics
 	client     azblob.ServiceURL // Azure sdk client
@@ -553,7 +553,11 @@ func (a *azureObjects) Shutdown(ctx context.Context) error {
 // StorageInfo - Not relevant to Azure backend.
 func (a *azureObjects) StorageInfo(ctx context.Context, _ bool) (si minio.StorageInfo, _ []error) {
 	si.Backend.Type = minio.BackendGateway
-	si.Backend.GatewayOnline = minio.IsBackendOnline(ctx, a.httpClient, a.endpoint)
+	host := a.endpoint.Host
+	if a.endpoint.Port() == "" {
+		host = a.endpoint.Host + ":" + a.endpoint.Scheme
+	}
+	si.Backend.GatewayOnline = minio.IsBackendOnline(ctx, host)
 	return si, nil
 }
 
diff --git a/cmd/gateway/gcs/gateway-gcs.go b/cmd/gateway/gcs/gateway-gcs.go
index 1bdd94f11..11f373e08 100644
--- a/cmd/gateway/gcs/gateway-gcs.go
+++ b/cmd/gateway/gcs/gateway-gcs.go
@@ -414,7 +414,7 @@ func (l *gcsGateway) Shutdown(ctx context.Context) error {
 // StorageInfo - Not relevant to GCS backend.
 func (l *gcsGateway) StorageInfo(ctx context.Context, _ bool) (si minio.StorageInfo, _ []error) {
 	si.Backend.Type = minio.BackendGateway
-	si.Backend.GatewayOnline = minio.IsBackendOnline(ctx, l.httpClient, "https://storage.googleapis.com")
+	si.Backend.GatewayOnline = minio.IsBackendOnline(ctx, "storage.googleapis.com:443")
 	return si, nil
 }
 
diff --git a/cmd/gateway/s3/gateway-s3.go b/cmd/gateway/s3/gateway-s3.go
index 3f3b86b71..95ca0f1bb 100644
--- a/cmd/gateway/s3/gateway-s3.go
+++ b/cmd/gateway/s3/gateway-s3.go
@@ -276,7 +276,11 @@ func (l *s3Objects) Shutdown(ctx context.Context) error {
 // StorageInfo is not relevant to S3 backend.
 func (l *s3Objects) StorageInfo(ctx context.Context, _ bool) (si minio.StorageInfo, _ []error) {
 	si.Backend.Type = minio.BackendGateway
-	si.Backend.GatewayOnline = minio.IsBackendOnline(ctx, l.HTTPClient, l.Client.EndpointURL().String())
+	host := l.Client.EndpointURL().Host
+	if l.Client.EndpointURL().Port() == "" {
+		host = l.Client.EndpointURL().Host + ":" + l.Client.EndpointURL().Scheme
+	}
+	si.Backend.GatewayOnline = minio.IsBackendOnline(ctx, host)
 	return si, nil
 }