Dockerfile Syntax

Dockerfiles are the blueprint for creating Docker images. By defining the build process in clear, efficient steps, they enable consistent deployment of applications. Mastering Dockerfile syntax is essential for leveraging Docker's full potential in both development and production environments.

In this section, we’ll cover the following topics:

Key Dockerfile Syntax

The syntax of a Dockerfile is straightforward, but understanding the nuances is critical for creating optimized images. Here are the key rules and practices:

1. Instructions Must Be in Uppercase

All Dockerfile instructions, such as FROM, RUN, and CMD, are written in uppercase. This helps distinguish reserved keywords and ensures consistency.

Example:

FROM ubuntu:20.04
RUN apt-get update

2. Arguments Follow Instructions

Each instruction is followed by arguments specific to its function:

• FROM defines the base image.
• COPY specifies source and destination paths.