Docker for Web Development: What It Is and a Practical Workflow

You pull a client project onto a new laptop, and an hour later you’re still fighting the wrong PHP version, a missing extension and a database that won’t start. Or a site runs perfectly on your machine, then breaks on staging for reasons nobody can reproduce. Docker exists to make those afternoons go away. Here’s what it actually does for web developers, what a realistic Docker workflow looks like from your laptop to production, and when it’s more tooling than a project needs.

What is Docker in web development?

Docker is a tool that packages an application together with everything it needs to run (runtime, libraries, system packages and configuration) into a container. In web development, that means your site’s web server, language runtime and database run in the same, predictable environment on every developer’s machine, in CI and on the server.

A few terms come up constantly:

• Image: a read-only template for a container, such as php:8.3-apache, node:22-alpine or mysql:8.0. Images are built in layers, so shared layers are downloaded and stored once.
• Container: a running instance of an image. You can start, stop, delete and recreate containers in seconds.
• Dockerfile: a text file with step-by-step instructions for building your own image.
• Docker Compose: a YAML file (usually compose.yaml or docker-compose.yml) that defines several containers, such as a web app, a database and a cache, and starts them together with one command.
• Volume: storage that lives outside the container, so data such as a database survives when the container is recreated.
• Registry: a place to store and share images. Docker Hub is the default public registry, with official images for common stacks like WordPress, Node.js, PHP, MySQL, PostgreSQL, Redis and Nginx.

What is Docker used for in web development?

Docker is mostly used to give every person and every server the same environment, so “it works on my machine” stops being a debate. In day-to-day web work, that shows up in a handful of ways:

• Local development environments: spin up PHP, Node.js, MySQL or PostgreSQL without installing them on your computer, and run projects with different versions side by side.
• Faster onboarding: a new developer clones the repo, runs one command and has a working site, instead of following a long setup document.
• Matching production: pin the same runtime and database versions you run live, so upgrade problems surface locally first.
• Consistent CI testing: run unit tests, linters and end-to-end tests inside the same image your app ships in.
• Deployment: ship a versioned image to a server, a container platform or Kubernetes, and roll back by running the previous image.
• Disposable services: try a search engine, a mail catcher or a new database version for an afternoon, then delete it without leaving anything behind.

Is Docker a virtual machine?

No. A virtual machine runs a complete guest operating system on virtualized hardware, while a container shares the host’s operating system kernel and isolates only the processes, files and network it needs. That’s why containers start in seconds and use far less memory and disk than VMs.

One nuance: on macOS and Windows, Docker Desktop runs containers inside a small, lightweight Linux VM behind the scenes, because Linux containers need a Linux kernel. You don’t manage that VM yourself, but it explains why file access and memory settings behave a bit differently on those systems than on a Linux machine.

What does a Docker web development workflow look like?

A typical Docker workflow has five stages: define the environment in code, develop locally in containers, build an image, test that image, and deploy the same image to production. The key idea is that the environment is described in files that live in your repository, so it’s versioned and reviewed like the rest of the code.

1. Define the environment

Add a compose.yaml for local services and, if you ship your own app image, a Dockerfile. Pin versions (for example mysql:8.0 rather than mysql:latest) so everyone gets the same thing. Keep secrets in an .env file that isn’t committed, and add a .dockerignore so folders like node_modules and .git don’t end up in your images.

2. Develop locally

Run docker compose up -d to start everything in the background. Your source code is usually bind-mounted into the container, so you edit files in your normal editor and the change appears immediately in the running site. Use docker compose logs -f to follow output and docker compose exec to run commands such as Composer, WP-CLI or npm inside a container.

3. Build an image

When it’s time to ship, docker build turns your Dockerfile into an image that contains your code and dependencies, not just a mount of your local folder. Tag it with a version or commit hash so you always know exactly what’s running.

4. Test the image

Run your tests against the built image, ideally in CI (GitHub Actions, GitLab CI or similar). Because CI uses the same image you’ll deploy, a passing test run tells you something real about production.

5. Deploy

Push the image to a registry (Docker Hub, GitHub Container Registry, or your cloud provider’s registry), then pull and run it on the server or container platform. Rolling back means running the previous tag. Your database data and uploads stay in volumes or managed services, not inside the container.

Example: a WordPress and MySQL setup with Docker Compose

Here’s a small, realistic compose.yaml for local WordPress development. It runs the official WordPress and MySQL images, keeps the database in a named volume and mounts your wp-content folder so you can work on themes and plugins directly:

services:
  db:
    image: mysql:8.0
    environment:
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: ${DB_PASSWORD}
      MYSQL_RANDOM_ROOT_PASSWORD: "1"
    volumes:
      - db_data:/var/lib/mysql

  wordpress:
    image: wordpress:latest
    depends_on:
      - db
    ports:
      - "8080:80"
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_USER: wordpress
      WORDPRESS_DB_PASSWORD: ${DB_PASSWORD}
      WORDPRESS_DB_NAME: wordpress
    volumes:
      - ./wp-content:/var/www/html/wp-content

volumes:
  db_data:

Put DB_PASSWORD=something-local in a .env file next to it, run docker compose up -d and open http://localhost:8080. The WordPress container reaches MySQL at the hostname db because Compose puts both services on a shared network and names them after their service keys. For real projects, pin the WordPress image to a specific version tag that matches your live site instead of latest.

Note that depends_on only controls start order. MySQL can take a few seconds to accept connections on the first run, so if WordPress shows a database error right away, give it a moment and reload.

What goes in a Dockerfile?

A Dockerfile starts from a base image, copies in your code, installs dependencies and defines how the container runs. Each instruction creates a layer, and Docker caches layers, so copying dependency files before the rest of your code keeps rebuilds fast.

This multi-stage example builds a front-end app with Node.js, then serves only the compiled files with Nginx, so the final image doesn’t carry the build tools:

FROM node:22-alpine AS build
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

FROM nginx:alpine
COPY --from=build /app/dist /usr/share/nginx/html
EXPOSE 80

Build and run it with docker build -t my-site:1.0 . and docker run -p 8080:80 my-site:1.0. The output folder (dist here) depends on your build tool, so adjust it to match.

What are the benefits and limits of Docker for web development?

Docker’s main benefit is a repeatable environment you can share and deploy; its main cost is an extra layer of tooling your team has to understand. Both are real, so it helps to weigh them honestly.

Benefits

• Consistency: the same versions of everything on every machine and server.
• Isolation: projects with conflicting PHP, Node.js or database versions run side by side without clashing.
• Environment as code: setup lives in the repo, gets reviewed in pull requests and doesn’t drift.
• Clean machines: remove a project’s containers and volumes and nothing is left behind.
• Predictable deploys and rollbacks: you ship a tagged image, not a list of server setup steps.

Limits

• Learning curve: images, volumes, networking and Compose take time to learn, and debugging inside a container is a skill of its own.
• Resource use on macOS and Windows: Docker Desktop runs a Linux VM, which uses memory and disk, and bind-mounted files can be slower than on native Linux, especially for projects with many small files.
• Image upkeep: base images need regular updates for security fixes, and bloated images slow down builds and deploys.
• Data still needs care: containers are disposable, so databases and uploads must live in volumes or external services, with backups.
• Hosting fit: most shared WordPress hosting doesn’t run containers, so you may use Docker locally and deploy files the traditional way.

When is Docker overkill?

Docker is often more than you need for a solo developer working on a single static site or a simple WordPress theme on a host that doesn’t run containers. If your stack is already easy to install and nobody else needs to reproduce your environment, the setup and maintenance can outweigh the payoff.

Lighter options can cover those cases: a static site generator with its own dev server, or a local WordPress app such as Local or a tool like wp-env (which uses Docker under the hood but hides most of it). Docker earns its keep as soon as you have several developers, several projects with different versions, services beyond a web server and database, or a deployment pipeline you want to be repeatable.

Is Docker free?

Docker Engine and the Docker command-line tools are open source and free. Docker Desktop is free for personal use, education, non-commercial open source projects and small businesses, but larger companies need a paid subscription under Docker’s terms. Since the thresholds and plans change from time to time, check Docker’s current pricing page before rolling it out across a team.

How do you get started with Docker?

Install Docker Desktop on macOS or Windows, or Docker Engine on Linux, then run docker run hello-world to confirm it works. From there, the quickest useful step is to copy a Compose file like the WordPress example above into a test project and start it.

Docker’s official documentation covers installation for each operating system, the full Dockerfile and Compose references, and guides for specific languages. Official images on Docker Hub also list their supported tags and environment variables, which is where settings like WORDPRESS_DB_HOST come from.

Frequently asked questions

Do I need Docker for web development?

No. Plenty of sites are built without it. Docker becomes valuable when several people or several projects need matching, reproducible environments, or when you want to deploy the exact environment you tested.

What’s the difference between Docker and Docker Compose?

Docker builds and runs individual containers. Docker Compose describes a multi-container setup, such as a web app plus a database, in one YAML file and starts or stops all of it with a single command.

Can I use Docker for WordPress development?

Yes. The official wordpress and mysql images on Docker Hub give you a working local site with a short Compose file, and you can mount your theme or plugin folders into the container to edit them live.

Is Docker good for beginners?

It’s approachable if you start small: run an official image, then try a two-service Compose file. Learn the basics of how the web server and database work first, though, because Docker adds a layer on top of them rather than replacing that knowledge.

If your agency needs reliable developers who can work inside your Docker setup, or help you standardize one across client projects, tell us about your project.

Brian Checkovich

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Brian Checkovich is a Partner and Finance Manager at Hey Reliable, where he leads financial strategy and plays a key role in day-to-day operations. With a background in finance and experiential marketing, and a degree in Marketing from the Un... read more