From a7a3ea87cfdfcf138dccb391e038d42ad3a98401 Mon Sep 17 00:00:00 2001
From: Omer Cohen <omer@cohen.io>
Date: Wed, 1 Mar 2017 10:43:39 +0200
Subject: [PATCH] add support for optional custom dns resolver

in cases of dynamic envinronments where containers move around
and respwan due to health checks, the IP of the forwarded host
might change nand should be resolved in case it's not found
this change introduces an optional dns resolver if it's needed
more info at https://tenzer.dk/nginx-with-dynamic-upstreams/
---
 Dockerfile | 3 ++-
 launch.sh  | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Dockerfile b/Dockerfile
index 20f86e7..9595c5c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,7 +2,8 @@ FROM nginx:alpine
 
 ENV HTPASSWD='foo:$apr1$odHl5EJN$KbxMfo86Qdve2FH4owePn.' \
     FORWARD_PORT=80 \
-    FORWARD_HOST=web
+    FORWARD_HOST=web \
+    DNS_RESOLVER=
 
 WORKDIR /opt
 
diff --git a/launch.sh b/launch.sh
index f5aba9e..f1a9050 100755
--- a/launch.sh
+++ b/launch.sh
@@ -4,4 +4,8 @@ rm /etc/nginx/conf.d/default.conf || :
 envsubst < auth.conf > /etc/nginx/conf.d/auth.conf
 envsubst < auth.htpasswd > /etc/nginx/auth.htpasswd
 
+if [ -n "${DNS_RESOLVER}" ]; then
+  echo "resolver ${DNS_RESOLVER};" >> /etc/nginx/conf.d/auth.conf
+fi
+
 nginx -g "daemon off;"