Docker Tutorial — ARG vs ENV
ARG is available only during build. ENV persists into the running container. Use ARG for build-time values (version numbers), ENV for runtime config.
Overview
ARG is available only during build. ENV persists into the running container. Use ARG for build-time values (version numbers), ENV for runtime config.
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 arg vs env 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, arg vs env 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 |
|---|---|
| ARG vs ENV | ARG is available only during build. ENV persists into the running container. |
Quick Reference
ARG vs ENV:
Key concept in Docker environment & configuration
See: docker --help for related commands
