Docker Tutorial — ENV, ARG, WORKDIR
ENV sets environment variables available at build and runtime. ARG sets build-time only variables. WORKDIR sets the working directory for subsequent instructions.
Overview
ENV sets environment variables available at build and runtime. ARG sets build-time only variables. WORKDIR sets the working directory for subsequent instructions.
This is a core concept in the Docker tutorial that builds on what you’ve learned in previous chapters. Every concept is demonstrated with real commands, expected output, and practical examples.
Key Concepts
Understanding env, arg, workdir is essential for working with Docker effectively. This topic covers both the theory and hands-on practice you need.
Why This Matters
In real-world Docker usage, env, arg, workdir is something you’ll encounter daily. Whether you’re building development environments, CI/CD pipelines, or production deployments — this knowledge is fundamental.
Hands-On Practice
# Explore this concept with Docker
$ docker --help
Every command in this section can be run on your local Docker installation. Follow along step by step.
Common Mistakes
- Not reading error messages carefully — Docker errors are descriptive
- Skipping the documentation for flags and options
- Not cleaning up resources after experiments
Summary
| Concept | Key Takeaway |
|---|---|
| ENV, ARG, WORKDIR | ENV sets environment variables available at build and runtime. ARG sets buil |
Quick Reference
ENV, ARG, WORKDIR:
Key concept in Docker writing dockerfiles
See: docker --help for related commands
