Make the load balancer configurable via env vars

[refs #006627177dc6]

Author: jfahrer

load_balancer/Dockerfile

@@ -1,3 +1,10 @@
 FROM jfahrer/nginx:latest
 
-COPY proxy.conf /etc/nginx/sites-available/default
+RUN apt-get update && apt-get install gettext-base
+
+ENV PROXY_PROTOCOL=http PROXY_UPSTREAM=example.com
+
+COPY proxy.conf /etc/nginx/sites-available/default.template
+COPY start.sh /
+
+CMD ["/start.sh"]

load_balancer/proxy.conf

@@ -3,8 +3,8 @@ server {
 
   resolver 127.0.0.11;
 
-  set $protocol http;
-  set $upstream example.com;
+  set $protocol $PROXY_PROTOCOL;
+  set $upstream $PROXY_UPSTREAM;
 
   location / {
     proxy_pass $protocol://$upstream$request_uri;

load_balancer/start.sh

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+
+envsubst '$PROXY_PROTOCOL,$PROXY_UPSTREAM' < /etc/nginx/sites-available/default.template > /etc/nginx/sites-available/default
+nginx -g 'daemon off;'