From b93641af9306aed281aa646e926b0997fce699bb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Mierzwa?= <l.mierzwa@gmail.com>
Date: Wed, 30 Jan 2019 15:36:49 +0000
Subject: [PATCH] fix(proxy): check for trailing slash on listen.prefix when
 proxy is on

When constructing proxy path to listen on for requests to pass upstream check if listen.prefix ends with / and if no inject it.

Fixes #386
---
 proxy.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/proxy.go b/proxy.go
index cac88197e..b8da77e49 100644
--- a/proxy.go
+++ b/proxy.go
@@ -15,7 +15,11 @@ import (
 )
 
 func proxyPathPrefix(name string) string {
-	return fmt.Sprintf("%sproxy/alertmanager/%s", config.Config.Listen.Prefix, name)
+	maybeSlash := ""
+	if !strings.HasSuffix(config.Config.Listen.Prefix, "/") {
+		maybeSlash = "/"
+	}
+	return fmt.Sprintf("%s%sproxy/alertmanager/%s", config.Config.Listen.Prefix, maybeSlash, name)
 }
 
 func proxyPath(name, path string) string {