What This Is
Docker packages applications and their dependencies into containers — isolated, reproducible units that run identically on any machine with Docker installed. The problem Docker solves is the gap between environments: code that works on a developer’s laptop but fails in staging because of a different PHP version, a missing system library, or a subtly different configuration. Containers eliminate that gap by shipping the entire runtime environment alongside the application.
We use Docker to standardise development environments across our team and to package applications for deployment. A developer joining a project runs docker compose up and gets the complete application stack — web server, PHP runtime, database, cache, and queue worker — running on their machine in minutes, configured identically to every other developer and to production. No manual installation of services, no version conflicts with other projects, no “it works on my machine” debugging sessions.
Docker sits in the space between application code and infrastructure. It is not a hosting platform or a server management tool — it is a packaging format. Your application, its runtime, its system dependencies, and its configuration become a single artifact that deploys predictably. Whether that container runs on a cloud server, a dedicated machine, or a developer’s laptop, the application behaves the same way.
When You Need This
Docker is the right choice when your project needs consistent environments across development, testing, and production or when the application stack is complex enough that manual setup creates friction. Common scenarios:
- Your application requires multiple services (web server, database, cache, queue worker) and setting them up manually on each developer’s machine is error-prone
- You need consistent development environments so every developer runs the same versions of PHP, Node, MySQL, and Redis
- CI/CD pipelines need to build, test, and deploy in isolated, reproducible environments
- The application runs on multiple servers and you need to ensure identical configuration across all of them
- You want to test against production-equivalent environments locally rather than discovering configuration differences during deployment
- Your project involves multiple language runtimes (PHP and Python, for example) that need to run side by side without version conflicts
This is not necessary for simple applications on managed hosting where the hosting provider handles the runtime environment. Docker adds value when environment complexity justifies the containerisation overhead.
How We Work
Docker projects use multi-stage Dockerfiles that separate build steps from runtime images. A PHP application’s Dockerfile might use a Node image to compile frontend assets, then copy those assets into a PHP-FPM image that contains only the production runtime. This produces smaller images without build tools, development dependencies, or source maps that do not belong in production.
Development environments use Docker Compose to define multi-container stacks. A docker-compose.yml file describes every service the application needs — web server, PHP-FPM, MySQL, PostgreSQL, Redis, Mailhog for email testing, and any other service. Volumes mount the source code so changes are reflected instantly. Port mappings expose services to the host machine for browser access and database client connections.
Image builds follow best practices for layer caching, size minimisation, and security. Dependency installation layers (Composer, npm) are separated from application code layers so that dependency changes do not invalidate the application code cache. Base images use official, maintained images with known security update schedules. Non-root users run application processes inside containers.
Deployment with Docker means building an image in CI, pushing it to a container registry, and pulling it on the target server. The same image that passed all tests in CI is the image that runs in production — no compilation on the server, no dependency installation during deployment, no possibility of a different build outcome.
What You Get
- Development environments — Docker Compose stacks that give every developer an identical, complete application environment
- Production images — multi-stage Dockerfiles producing optimised, minimal images for deployment
- CI/CD integration — containerised build and test pipelines that run in the same environment as production
- Service orchestration — multi-container applications with web servers, databases, caches, and workers managed as a unit
- Environment parity — identical runtime configurations across development, staging, and production
- Dependency isolation — multiple projects with different PHP, Node, or database versions running simultaneously on the same machine
- Reproducible builds — image artifacts that produce the same behaviour regardless of where they run
Technologies We Use
- Docker Engine — container runtime for building and running containers
- Docker Compose — multi-container application definition and orchestration for development environments
- Multi-stage builds — Dockerfile patterns that separate build and runtime stages
- Alpine / Debian-slim images — minimal base images for smaller container sizes
- Docker Hub / private registries — image storage and distribution
- Docker volumes — persistent data storage for databases and uploaded files
- Docker networks — isolated networking between containers in a stack
Related Systems
Docker containers run applications built with Laravel, Node.js, and Python. Development stacks include MySQL, PostgreSQL, and Redis containers. Production containers are served by Nginx and run on Linux hosts. Docker is also covered from an infrastructure perspective on our Docker infrastructure page.
Talk to Us About Docker
If your development workflow needs standardisation or your deployment pipeline needs reproducibility, get in touch and we will containerise your application stack.
