Add ec2 private ip to server name for LBs

Allow LBs to talk to application by adding the EC2 ipv4 address to
server_name.

Author: bennettgoble

src/docker-entrypoint.sh

@@ -7,6 +7,17 @@ if [[ -n $PROXY_REVERSE_URL ]]; then
   export UPSTREAM_SERVER=${PROXY_REVERSE_URL#http://}
 fi
 
+# Add EC2 IPv4 address to allowed hosts so that load balancers can talk to us
+if [[ "$SERVER_NAME" != "_" ]]; then
+  local_ipv4=$(curl --connect-timeout 2 -s http://169.254.169.254/2009-04-04/meta-data/local-ipv4 || true 2>/dev/null)
+  if [[ -n "$local_ipv4" ]]
+  then
+    export SERVER_NAME="$SERVER_NAME $local_ipv4"
+  fi
+fi
+
+exec "$@"
+
 run-parts --exit-on-error /docker-entrypoint.d
 
 exec "$@"