docker-knowledge-patch

name	docker-knowledge-patch
description	Docker changes since training cutoff (latest: 0.31.0) — Rego source policies, bake --var flag, semvercmp function, env lookup disable. Load before working with Docker.
category	knowledge-patch
version	0.31.0
license	MIT
metadata	{"author":"Nevaberry"}

Docker Knowledge Patch

Claude Opus 4.6 knows Docker Engine through 24.x and Compose through 2.x. This skill provides features from Buildx 0.31.0 (2026-01-22).

Index

Topic	Reference	Key features
Buildx & Bake	references/buildx-bake.md	Rego source policies, --var flag, semvercmp, env lookup disable

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Quick Reference

Source policy enforcement with Rego (Buildx 0.31.0)

Buildx enforces build policies written in Rego (Open Policy Agent). Policies control what sources/images are allowed during builds.

# Explicit policy file
docker buildx build --policy policy.rego .

# Auto-loads Dockerfile.rego or app.Dockerfile.rego alongside the Dockerfile
docker buildx build -f app.Dockerfile .

# Evaluate and test policies
docker buildx policy eval
docker buildx policy test

In Bake, use the policy key or rely on auto-loading:

# docker-bake.hcl
target "app" {
  dockerfile = "Dockerfile"
  policy     = "policy.rego"
}

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Bake --var flag (Buildx 0.31.0)

Set HCL variables directly from the command line instead of using environment variables:

docker buildx bake --var FOO=bar --var VERSION=1.2.3

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Bake semvercmp function (Buildx 0.31.0)

Stdlib function for semantic version comparisons in Bake HCL files.

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Bake env lookup disable (Buildx 0.31.0)

Option to prevent Bake from reading host environment variables, useful for reproducible builds.

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Reference Files

File	Contents
buildx-bake.md	Rego source policy enforcement (auto-loading, explicit --policy, policy eval/test, Bake policy key), --var flag for HCL variables, semvercmp stdlib function, env lookup disable