VPS hosting Docker

Docker is application containerization platform allowing packaging application with all dependencies into isolated container. Container is lightweight virtual environment containing only application and its libraries, uses host system kernel, launches in seconds (VM launches in minutes), consumes less resources than full virtual machine. Why Docker on VPS: application isolation—10 projects on different stacks (PHP 7.4, PHP 8.2, Node.js, Python) work on one VPS without conflicts, portability—works identically on your laptop, staging and production servers ("works on my machine" no longer problem), microservice architecture—break monolith into independent containerized services, fast deployment—update through container replacement in seconds, rollback to previous version with one command. Docker became standard in modern web development and DevOps.

Containers and virtual machines (VM) solve similar isolation tasks but work differently. Virtual machine: includes full OS copy (guest OS), works through hypervisor (VMware, Hyper-V, KVM), "heavy"—VM occupies gigabytes disk and hundreds megabytes RAM for guest OS, starts in minutes (needs loading entire OS). Docker container: uses host system kernel (no guest OS), works at Linux process level, "light"—container occupies tens/hundreds megabytes, contains only application, starts in seconds. Analogy: VM is whole house with all utilities, container is apartment in common house (shares infrastructure). On one VPS can run: 5-10 virtual machines or 50-100 Docker containers. Containers more efficient for most tasks.

Docker can be installed on most VPS but there are requirements and nuances. Technical requirements: Linux kernel 3.10+ (modern distros Ubuntu 20.04+, Debian 10+, CentOS 7+ suitable), x86_64/amd64 architecture (ARM supported but limited), minimum 1 GB RAM for Docker Engine + several containers, KVM or Xen virtualization technology (OpenVZ doesn't fully support Docker). Pre-installed Docker VPS advantages: save 1-2 hours on installation and setup, correct out-of-box configuration (storage drivers, networking, security), provider-verified compatibility, support familiar with Docker and can help. Can install Docker manually: on Ubuntu: apt-get install docker.io or through official Docker repository, on CentOS: yum install docker, configure docker-compose, access rights, system startup. For production recommend VPS with pre-installed Docker—less chance to mistake in setup.

Quantity depends on VPS resources and container requirements. Light containers (static sites, simple APIs): 2 GB RAM VPS—20-50 containers, 4 GB RAM VPS—50-100 containers, each container consumes 20-50 MB RAM. Medium containers (Node.js, PHP-FPM applications): 4 GB RAM VPS—10-20 containers, 8 GB RAM VPS—20-40 containers, each consumes 100-200 MB RAM. Heavy containers (databases, cache, queues): 8 GB RAM VPS—5-10 containers, each consumes 500 MB - 2 GB RAM (load-dependent). Practical example: 4 GB RAM VPS can comfortably run typical microservice application: 1× Nginx (50 MB), 3× Node.js API (300 MB × 3 = 900 MB), 1× PostgreSQL (500 MB), 1× Redis (100 MB), 2× Worker processes (200 MB × 2 = 400 MB), total: ~2 GB used, 2 GB reserve for OS buffers and load peaks. Monitor consumption with docker stats and scale VPS when needed.