Werkdock skeleton: doctor, load, run over the bwrap engine (Go)

The minimal build-capable CLI decided in RFC 0002's outcome: stdlib-only
Go module, one static binary.

- engine: RunSpec behind the Engine interface (RFC 0001); the Bwrap
  engine ports Werkator's hardened invocation — uid-0 mapping, read-only
  rootfs at /, proc/dev/tmp/root before the user binds so binds below
  them land inside, mountpoint pre-creation in the rootfs including file
  mountpoints, and a guard against binds escaping the rootfs. --clearenv
  gives docker-style clean environments (HOME/PATH set explicitly).
- store: images under $WERKDOCK_HOME (default ~/.werkdock), load
  unpacks via the tar CLI into a tmp dir and renames atomically.
- cli: docker-shaped run flags (-v/-e/-w/--rm); refused docker flags
  (-p, --network, --memory, --cpus, --user, -d) fail loudly with the
  reason; exit codes follow docker (125 CLI errors, child code through).
- doctor: port of werkator-build-prerequisites.sh — userns probe with
  the three signals, tar/zstd, free space and group-quota headroom via
  testable df/quota parsers, same PASS/FAIL output.
- tests: argv golden test, mountpoint and escape tests, flag refusals,
  store round trip, doctor parsers — plus real-sandbox integration
  tests that skip where bwrap or userns are unavailable.

Also records in step 21: RFC 0002 levels 2/3 deferred; next goal is
sandbox builds of Werkator, Werkbaum, and Werkdock itself.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
mhoennig
2026-09-01 07:01:21 +02:00
co-authored by Claude Fable 5
parent 4fba73a1d0
commit 67e5b120e7
18 changed files with 1629 additions and 2 deletions
@@ -57,6 +57,7 @@ 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.
- Decided 2026-09-01: RFC 0002 levels 2 and 3 are deferred indefinitely; the immediate goal of this session is the minimal build-capable CLI — `doctor`, `load`, `run` — sufficient for the sandbox builds of Werkator, Werkbaum (Kotlin/Gradle backend plus Node frontend), and Werkdock itself (Go); while Werkdock lives in this repository, its own CI is just a build definition in this repository's `.werkator.yml`.
- 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.