Step‑by‑Step Deployment of Frontend and Backend High‑Availability Services Using Docker, Nginx and Keepalived

The article addresses the problem of insufficient physical servers and demonstrates a complete solution for building a highly available front‑end and back‑end system using Docker, Keepalived, and Nginx.

System preparation : install Docker on an Ubuntu 16.04 host (minimum 4 CPU, 8 GB RAM) and create a custom Docker network mynet with a subnet (e.g., 172.18.0.0/24).

Keepalived installation : download the source, install required build tools, compile and install Keepalived, then create the service scripts ( /etc/keepalived/keepalived.conf) with a virtual IP (e.g., 172.18.0.220) and VRRP instance configuration. Adjust the startup script to use . /lib/lsb/init-functions for compatibility with non‑RedHat systems.

Nginx setup : install the official Nginx package, configure an upstream block pointing to backend servers, and set the virtual server to listen on the virtual IP. Add a simple HTML page with a Vue.js front‑end that calls /api/test on the backend.

Backend Docker image : create a Dockerfile based on openjdk:10 that copies docker_server.jar and runs it with java -jar. Build the image ( docker build -t myopenjdk .) and create six data volumes (S1‑S6) to store the JAR file.

Deploy backend containers : run six containers ( server_1 … server_6) on mynet with static IPs ( 172.18.0.101 ‑ .106) and mount the corresponding data volume. Each container starts the Java application automatically.

High‑availability front‑end containers : create two Keepalived‑enabled containers ( centos_web_master and centos_web_slave) with different priorities and VRRP states (MASTER/SLAVE). Configure Nginx inside each container to proxy to the backend pool and to use the same virtual IP ( 172.18.0.210).

Testing : access the virtual IP from a browser; the page shows the Vue.js UI and displays the backend server port returned by /api/test. Stop the master container to verify automatic failover to the slave, and stop individual backend containers to confirm Nginx load‑balancing.

Portainer installation : pull the Portainer image and run it with -p 9000:9000 and -v /var/run/docker.sock:/var/run/docker.sock. Use the web UI (admin/password) to monitor all containers and their statuses.

The guide concludes with a reminder that deeper topics such as Docker Compose, Kubernetes, and advanced network management require further study.