Docker hosting for Java containers

When Docker is the right choice

Use Docker when you already build images, when your application needs native libraries or a specific JDK build, or when you want the same artifact in CI, staging and production. On a single VPS, Docker Compose is the simple way to run it, without the overhead of Kubernetes.

How it works on our server

• Docker Engine and the Compose plugin installed from the official repository.
• Your container runs from /opt/docker-app/compose.yaml and restarts automatically.
• Nginx terminates HTTPS and proxies to the container on localhost.
• Update with sudo deploy-app registry/image:tag. It pulls the image and recreates the container.
• Private registries work. Log in once with docker login and the credentials stay on your server.

Container memory and the JVM

Modern JVMs read the container memory limit. Use -XX:MaxRAMPercentage=60 instead of a fixed -Xmx so the heap follows the limit. Set an explicit memory limit on the container, otherwise a leak can consume the whole server. Leave room for metaspace, thread stacks and native memory: the heap is not the whole process.

services:
  app:
    image: registry.example.com/myapp:1.4.2
    restart: unless-stopped
    network_mode: host
    mem_limit: 3g
    environment:
      JAVA_TOOL_OPTIONS: "-XX:MaxRAMPercentage=60"
      SERVER_PORT: "8080"

Databases in containers

You can run your database in Docker too, or install MySQL, MariaDB or PostgreSQL directly on the server for simpler backups. We can set up either.