Think Twice Before Using COPY --link in Your Docker Builds

A Deep Dive into Docker's COPY --link: When It Helps, When It Hurts, and Why Small Apps Should Be Cautious

Introduction

Docker 25.0 introduced a powerful but often overlooked enhancement: the --link flag for the COPY command. This feature is available only when using BuildKit, Docker’s modern build engine, and it can significantly boost your build performance and reduce disk usage—especially in complex projects.