{
  "slug": "dockerfile-archives-support-zstd-build-contexts-and-add-7770d6830eb0",
  "title": "Dockerfile archives support zstd build contexts and ADD",
  "tools": [
    "buildkit"
  ],
  "tags": [
    "agent"
  ],
  "introduced_at": "2026-09-02T16:08:38.000Z",
  "announced_at": "2026-09-02T16:08:38.000Z",
  "effective_at": null,
  "date_basis": "source-publication",
  "status": "unknown",
  "how": {
    "incantation": "When building with Dockerfile syntax 1.27.0, a zstd-compressed archive can be the build context or an `ADD` source. Use the archive as the context, or add its files with `ADD <archive> <destination>`; local tar archives unpack by default.",
    "examples": [
      "# syntax=docker.io/docker/dockerfile-upstream:1.27.0\nFROM alpine\nADD <archive.tar.zst> /destination/",
      "docker build -f <Dockerfile> <context.tar.zst>"
    ],
    "gotchas": [
      "Version: dockerfile/1.27.0",
      "<archive.tar.zst> (required): The local archive source; recognized compression is determined from file contents, not its filename.",
      "<destination> (required): Image path where `ADD` extracts the archive contents.",
      "--unpack=<bool>: Controls automatic archive extraction. Local tar archives unpack by default; no mutually exclusive object subkeys apply.",
      "Dockerfile syntax version (required): Use `docker/dockerfile-upstream:1.27.0` to select the release's Dockerfile frontend.",
      "Prerequisite: Use Dockerfile syntax `docker/dockerfile-upstream:1.27.0` or a frontend that supports the change."
    ]
  },
  "why_it_matters": "Build an image from a zstd-compressed archive or add files from one with Dockerfile instructions.",
  "sources": [
    "https://github.com/moby/buildkit/releases/tag/dockerfile/1.27.0",
    "https://github.com/moby/buildkit/blob/dockerfile/1.27.0/frontend/dockerfile/docs/reference.md"
  ],
  "rank": 0.97033,
  "judge": {
    "publish": true,
    "judge_model": "codex-cli/gpt-6-luna+typesafe/jev-1.13.0",
    "prompt_version": "extract-v7+enrich-v2+judge-v2x3+jev-publish-v1"
  },
  "review_state": "approved",
  "provenance": {
    "run_id": "wave1-20261014",
    "verdict_id": "wave1-20261014:wave1-20261014-2840d3a412d48dca-0:gate",
    "evidence_hash": "839d39613b4a07df97c1f8855c45cc070da20eb62f2df72ad359a90be23266e3"
  },
  "review": {
    "draft_hash": "a13f02867422798733455bcb268326ad50b3aa3021d83c6319f774fb5720b625",
    "reviewer": "publication-gate",
    "reviewed_at": "2026-10-07T00:00:00.000Z",
    "decision": "wave1-20261014:gate",
    "reason": "3 of 3 judge runs approved with p_yes >= 0.9 (mean 0.97 >= 0.9; 2 needed) and Jev gave 0.62 (>= 0.6 needed)."
  }
}