Dockerfile

A declarative text manifest that automates the sequential assembly of container images using specific build instructions.

Dockerfiles serve as the definitive blueprint for containerized infrastructure. Each file begins with a base image (such as alpine:3.19) and layers system dependencies through a series of capital-letter verbs. Use RUN to install packages (apt-get install -y python3), COPY to transfer local source code, and EXPOSE to define network ports (like 8080). This approach guarantees environment parity across dev and production by locking down the OS and runtime in a version-controlled script. By utilizing multi-stage builds (the AS keyword), operators can separate build-time tools from the final executable to keep production images lean and secure.

https://docs.docker.com/reference/dockerfile/