docker-syntax-buildkit

Quick Reference

Syntax Directive

ALWAYS include at the very top of every Dockerfile, before any other instruction:

# syntax=docker/dockerfile:1

This enables heredoc syntax, --mount flags, --chmod/--link/--parents/--exclude on COPY/ADD, the # check directive, and all other BuildKit extensions. ALWAYS use docker/dockerfile:1 (not 1.0 or a fixed minor version) to get the latest stable features.

Mount Types Overview