Add gettext package installation to Dockerfile

Author: Robbie1977

Dockerfile

@@ -12,7 +12,8 @@ COPY $NGINX_CONF /etc/nginx/nginx.conf.template
 COPY health-monitor.sh /usr/local/bin/health-monitor.sh
 
 RUN mkdir -p /var/cache/nginx/owlery && chown -R nginx:nginx /var/cache/nginx && \
-    chmod +x /usr/local/bin/health-monitor.sh
+    chmod +x /usr/local/bin/health-monitor.sh && \
+    apk add --no-cache gettext
 
 EXPOSE 80 8080