werkator/docs/plan/21-werkdock-extraction-and-webspace-install.md

Step 21: Werkdock Extraction and the Managed-Webspace Install Path

Prerequisites: step 17 (merged to main as PR #4, commit 71f1fc6). Read README.md first. This step is a roadmap: it records where the bwrap work drifted from the original intent, and breaks the correction into sessions (A–D below). Each session is sized like a normal step. Werkdock is developed in the werkdock/ subdirectory of this repository first and moves to its own repository later; the whole effort runs on the branch werkdock-extraction.

What Was Planned, and What the Branch Built Instead

Two intents from the existing documentation ended up competing in the bwrap work merged as PR #4:

1. ADR 0006 / step 15: Werkator is built locally and distributed as a self-contained runtime bundle; the target host only unpacks and runs it. That install path exists and is documented — but only for Hostsharing container servers (docs/deployment.md, "Hosts Without a Java Runtime", verified on vm4006).
2. Step 17: bubblewrap as the third build runtime, with the stated target use case "Werkator builds Werkator itself on a Managed Webspace".

Step 17 itself proved the self-build unnecessary for deployment: the precondition section records that the runtime bundle runs on the webspace unchanged (glibc floor GLIBC_2.15, checked on h68), "so no container build and no second build machine are needed for this platform". The merged code nevertheless implements the self-build end to end — tools/remote install clones the repository onto the webspace and tools/remote build builds Werkator there inside the bwrap sandbox. That is a working prototype and a good proof of the sandbox, but as a deployment path it inverts intent 1: the webspace should receive a locally built bundle, exactly like vm4006 does.

Independently, the bwrap machinery itself (rootfs archive build, prerequisites check, the mount/uid-mapping invocation in BwrapBuildRunner) is generic filesystem isolation, not Werkator-specific. The plan is to extract it as a small docker-like tool: filesystem isolation only, everything else (network, uid, /proc, /dev) shared with the host — usable on Managed Webspaces to install one's own program versions, with Werkator as its first consumer. It grows in the werkdock/ subdirectory of this repository and moves to its own repository once it stands on its own.

Naming the Extracted Tool

Werkdock — decided 2026-09-01. A dock is the enclosed basin in which ships are built, so the name carries both halves of the tool at once: the closed-off area (filesystem isolation) and the docker-light ambition. The metaphor extends to the contract: the dock gate controls what passes, while the water outside is shared with the whole harbor — network, uid, /proc, /dev from the host. The audible nearness to Docker is read as an honest genre label, not as an accident. "Dock" is the same word in German and English — the only candidate that needed no translation in either direction. As of 2026-09-01 there is no GitHub repository, product, or company of that name.

Considered and dropped, over three naming rounds:

• Werkwrap (the working title): names the mechanism — a wrapper over bwrap — rather than the result; one abandoned zero-star GitHub repo of that name also exists.
• Werkroot: technically the most precise (the isolated artifact is a root filesystem; lineage chroot → fakeroot), completely free — the runner-up.
• Werkgrund: "own ground to build on", free; but "Grund" also reads as "reason" and signals neither isolation nor containers.
• German root-words: Wurzelwerk (the finest word, but a well-known German gardening brand, and it inverts the Werk-family order), Werkwurzel (family-true but botanical), Stammwerk, Wurzelraum.
• Enclosed-area words: Werkkammer (sober engineering chamber), Werkinsel (isolation literally from insula), Werkgehege (best tagline — „damit sich Programmversionen nicht ins Gehege kommen" — but zoo overtones), Werkklause, Werkzone, Werkhof (the Swiss municipal works yard), Werkgarten (walled-garden connotation).
• Werkbank (taken on GitHub at least twice, and a common German word), Werkbox (crowded *box sandbox namespace), Kapsel (SAP's Kapsel framework).

The Sessions

A — Close step 17's open ends (this repo)

The BuildRunner half is a keeper regardless of the extraction; it is merged (PR #4), but its paperwork is not finished.

• Rename docs/prs/2026-08-31-PR#000-bwrap-build-runtime.md and its scenario IDs to the real number, #4.
• Mark tools/remote install/build in the script header as a prototype of the self-build workflow, superseded by session D.
• Write the bwrap-runtime ADR — step 17 says "ADR 0007", but 0007 is taken by build definitions since 2026-08-28; the ADR becomes 0008.
• Update the architecture skill: it does not mention the third runtime yet.

B — Bootstrap Werkdock (subdirectory werkdock/, later its own repo)

A docker-like CLI over bwrap, filesystem isolation only.

• Semantics: an image is a rootfs archive; an instance is an unpacked, writable directory tree and corresponds to a docker container; werkdock run [flags] IMAGE [CMD...] executes in the sandbox with uid 0 mapped to the calling user.
• The surface is docker-compatible as far as the filesystem-only contract allows — verbs, flags, and (deferred) a Docker-Engine-API daemon for Testcontainers; levels and limits in Werkdock RFC 0002.
• Host-shared by design, not by omission: network, uid mapping, /proc, /dev, /tmp come from the host; document this as the contract, since it is what makes the tool work without root on a Managed Webspace.
• Moves in from Werkator: tools/build-bwrap-rootfs.sh (becomes the image build), the generic half of tools/werkator-build-prerequisites.sh (becomes werkdock doctor: userns capability, quota headroom), and the invocation logic of BwrapBuildRunner (mount ordering, mountpoint pre-creation, uid mapping — the parts hardened on the real webspace; the squash commit 71f1fc6 preserves the individual fix messages).
• Known floor: bubblewrap 0.8.0 on the webspaces has no --overlay; writable spots are tmpfs/bind mounts until the platform reaches 0.9.
• Own docs, plan, and ADRs under werkdock/ from the start, so the later repository split is a directory move; the Werkator side only keeps what is Werkator-specific (the git-metadata mounts of step 16 and the config pinning).
• Keep werkdock/ self-contained: no imports from Werkator code, no Gradle coupling to the Werkator build — it must build and test on its own.

C — Werkator consumes Werkdock (this repo, after B)

• BwrapBuildRunner shells out to werkdock run instead of assembling the raw bwrap argv — same pattern as git and docker: CLI, no library.
• Config keys (bwrap.enabled, bwrap.rootfs) and their pinning stay as they are; only the executor behind them changes.
• Decide in the step: whether the git-metadata mounts stay Werkator-side (passed as extra --bind/--tmpfs options to werkdock run) or become a Werkdock feature; the secrets-masking of .git/werkator/ must hold either way.

D — The Managed-Webspace install path (this repo, independent of B/C)

Bring intent 1 to the webspace: build locally, install the bundle — Werkator never builds itself on the target.

• tools/remote install loses the repository clone and the GitHub-key step; it uploads the locally built runtime bundle (built on demand, as today) and runs init.
• The rootfs upload stays, but for its real purpose: the sandbox for the repositories this instance watches, not for building Werkator.
• tools/remote build (the self-build) is retired with session A's prototype marker.
• docs/deployment.md gains "Hostsharing Managed Webspace" as the third deployment variant — step 17 required this to be written from a verified setup, and the branch's live run provides exactly that.

Acceptance Criteria

• Session A: PR-doc renamed to #4, ADR 0008 written, architecture skill mentions the third runtime, tools/remote header carries the prototype note.
• Session B: the werkdock/ subdirectory holds a self-contained tool in which werkdock doctor, an image build, and werkdock run work on a Managed Webspace without any Werkator involvement.
• Session C: ./gradlew build green with BwrapBuildRunner delegating to werkdock; the pinned-key tests and the metadata-masking tests unchanged and green.
• Session D: a fresh Managed Webspace reaches a running, HTTPS-reachable Werkator via tools/remote werkator install + start without ever compiling on the target; docs/deployment.md documents it.