dockerfile: trying a different approach for entrypoint

Dockerfile

@@ -8,9 +8,4 @@ RUN dnf install -y golang git bzr && \
 	go get github.com/vbatts/imgsrv && \
 	rm -rf /usr/local/src /usr/local/pkg && \
 	dnf remove -y golang git bzr
-ENTRYPOINT /usr/local/bin/imgsrv \
+ENTRYPOINT ["/usr/local/src/github.com/vbatts/imgsrv/run.sh"]
-	-server \
-	-mongo-host=$MONGODB_SERVICE_HOST:$MONGODB_SERVICE_PORT \
-	-mongo-db=$MONGODB_DATABASE \
-	-mongo-username=$DATABASE_USER \
-	-mongo-password=$DATABASE_PASSWORD

run.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+binary=${APP_BINARY:-/usr/local/bin/imgsrv}
+MONGODB_SERVICE_HOST=${MONGODB_SERVICE_HOST:-localhost}
+MONGODB_SERVICE_PORT=${MONGODB_SERVICE_PORT:-27017}
+
+args=""
+if [ ! -z "${DATABASE_USER}" ] ; then
+	args=" ${args} -mongo-username=$DATABASE_USER "
+fi
+
+if [ ! -z "${DATABASE_PASSWORD}" ] ; then
+	args=" ${args} -mongo-password=$DATABASE_PASSWORD "
+fi
+
+if ! echo "${1:-$@}" | grep -q '\-mongo-host' ; then 
+	args=" ${args} -mongo-host=$MONGODB_SERVICE_HOST:$MONGODB_SERVICE_PORT "
+fi
+
+${binary} \
+	-server \
+	-mongo-db=$MONGODB_DATABASE \
+	${1:-$@} \
+	${args}