fix(container-logs): let the grant serve a real Docker client

[pofallon]

Why now

container-logs@1 has shipped since 0.11.0-rc.1 — proxy, grant, consent, labels, tests — with no provider to exercise it. I packaged one (Dozzle, try-hola/apps#160) and installed it on a VM. It crash-looped:

{"level":"fatal","message":"Could not connect to any Docker Engine"}
[docker-proxy] denied: HEAD /_ping
[docker-proxy] denied: GET /v1.52/info

Three defects, all shape rather than policy — nothing here widens what the grant discloses.

1. HEAD was refused

The allowlist was GET-only. Docker's own client pings with HEAD /_ping before anything else, so every standard client was rejected on its first call — and reported it as "no engine", not as a refusal.

HEAD is now allowed wherever GET is. It returns headers and no body, so it reveals strictly less than the GET it mirrors, and it opens nothing new: HEAD /containers/{id}/archive is still 403.

2. GET /info was refused outright

A client on Docker's SDK calls it to decide an engine is really there, and exits without it. Refusing it meant the grant could not serve the clients it exists for.

It is now rebuilt from an allowlist, exactly as inspect is. Kept: Name, ServerVersion, OSType, OperatingSystem, Architecture, NCPU, MemTotal, container counts — enough to identify and size the engine. Dropped: RegistryConfig, Labels, Plugins, DockerRootDir, SecurityOptions, Swarm, KernelVersion, and above all HttpProxy/HttpsProxy, which routinely embed credentials.

3. The redacted inspect was shape-incompatible

It omitted HostConfig, Mounts and NetworkSettings entirely. A real daemon always returns them, so clients walk them unchecked — Dozzle segfaults on HostConfig.PortBindings:

panic: runtime error: invalid memory address or nil pointer dereference
docker.newContainerFromJSON(...) /dozzle/internal/container/docker/client.go:675

Dropping the field denied the client, not the data. They are now present but empty — { PortBindings: {} }, [], { Networks: {} } — which puts the same nothing on the wire in a shape an SDK client can parse. No host port map, no bind sources, no network topology.

Verified on a VM, against the real app

	before	after
dozzle	crash-loop, "Could not connect to any Docker Engine"	Connected to Docker, Accepting connections on :8080, healthy
a neighbour app's logs	—	read through the grant, with sh.hola.app / sh.hola.deployment labels intact
neighbour's inspect	—	no Env

And the envelope still holds — probed from inside the deployment:

HEAD   /_ping                                     200
GET    /info                                      200   (redacted)
GET    /containers/json                           200
GET    /v1.52/containers/json                     200
GET    /containers/<id>/json                      200   (redacted)
GET    /containers/<id>/logs                      200
GET    /containers/<id>/stats                     403
GET    /containers/<id>/archive?path=/etc/passwd  403
GET    /images/json                               403
GET    /secrets                                   403
GET    /volumes                                   403
POST   /containers/<id>/restart                   403
POST   /containers/<id>/exec                      403
DELETE /containers/<id>                           403

Left deliberately closed

/containers/{id}/stats stays 403, so Dozzle shows logs without resource graphs. It is benign data (counters for containers the caller can already list) and would be easy to add, but nothing needs it to function and I would rather widen the envelope on a real request than on a nice-to-have. Worth a decision alongside #438.

Tests

docker-proxy.test.ts 26 pass: HEAD allowed on each allowed path and on none of the refused ones; every mutating verb still refused; /info allowed versioned and unversioned; redactInfo keeps the identifying fields, drops the proxy URLs (asserted by searching the serialized body for the credential), drops host configuration; inspect keeps the structural fields present-but-empty while leaking no port map, bind source or IP. Three existing assertions were updated — they pinned the absent-field shape this fixes.

Full gate green: typecheck, lint, typecheck, test (983 server + 360 web), build.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Vck5KSX2CLxhohx14nb5Sh