What Is a .dockerignore file?

a .dockerignore file explained, including what it does and how it matters in CI/CD.

A .dockerignore file lists files and directories to exclude from the Docker build context.

What it is

It keeps node_modules, .git, and build output out of the context sent to the daemon, which speeds builds and avoids leaking secrets into images.

Why it matters in CI/CD

In CI, a good .dockerignore dramatically cuts the build context size and build time, and prevents busting the layer cache on irrelevant file changes.

Key takeaways

• .dockerignore trims the build context.
• It speeds builds and avoids leaks.
• Improves Docker layer cache hits.

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