package-updater/CLAUDE.md

package-updater — Claude context

Master/agent fleet updater. A master (UI behind OIDC, Postgres) shows every Compose stack, Swarm service and container on every machine and starts updates; one agent per machine (/var/run/docker.sock mounted) reports its inventory and runs the jobs. Both are in one image: updater-master and updater-agent.

See README.md for user-facing docs. This file is for working ON the code.

Commands

go test ./...                          # all tests, fast (no docker, no postgres)
go test -race ./internal/agent/... ./internal/master/... ./internal/e2e/
go test -run TestFoo ./internal/master/hub    # single test
go build ./cmd/master ./cmd/agent      # produce ./master and ./agent
docker build -t package-updater:dev .  # multi-stage, builds golang:1.26-alpine

# Postgres tests (store), against any throwaway database:
DATABASE_URL=postgres://... go test -tags integration ./internal/master/store/

Architecture (one-line per package)

• cmd/master — wiring only: config → store → hub → jobs → web + webhook, two listeners (UI, agents over pinned TLS)
• cmd/agent — wiring only: config → docker client → inventory → job runner → master connection
• internal/protocol — the WebSocket messages both sides speak (Version, JobStart, JobResult, ...)
• internal/pin — master key pair, certificate and fingerprint pinning
• internal/agenttoken — agent token generation and hashing
• internal/imageref — image reference parsing (repo, tag, digest)
• internal/logging — slog JSON, request-id context propagation
• internal/agent/config — env-var loading; fails fast on missing MASTER_URL/MASTER_KEY/AGENT_TOKEN
• internal/agent/inventory — reads Compose, Swarm and plain containers from the Docker daemon
• internal/agent/conn — dial, hello, snapshot, job messages, reconnect with backoff; one writer goroutine per session
• internal/agent/updater — job Runner (single FIFO worker, outbox until acked), Compose and Swarm executors, override file, mount-root check, registry auth
• internal/master/config — env-var loading
• internal/master/store — Postgres access and migrations
• internal/master/hub — agent connections: auth, per-connection writer, routing, job reconcile on hello
• internal/master/jobs — decides whether a service may be updated and starts a job on the right agent
• internal/master/webhook — POST /update: records the available version, starts jobs for auto services, waits for them
• internal/master/web, webauth — HTMX UI behind OIDC login, SSE signals
• internal/master/events — in-process publish/subscribe for UI refresh signals
• internal/master/model — domain types shared by the above

Design intent (do not break without discussion)

• Single FIFO worker per agent by design (internal/agent/updater/runner.go). Two docker compose calls against the same stack race.
• One queued or running job per service, enforced by the unique index update_jobs_one_active (not by application code).
• The agent writes exactly one file, <stack dir>/compose.override.yaml, and only if it is absent or starts with the header line. It refuses the job when any other auto-loaded override name exists.
• Every config file and the override path must be inside a read-write bind mount of the agent's own container whose source equals its destination. Mounts are read per job (ContainerInspect(SELF_ID)) and checked after symlink resolution. This replaces the old STACKS_ROOT.
• Self-protection on the master: a service is refused when its image repo equals the repo of AGENT_IMAGE or the row has the self flag. The agent does not re-check.
• Unknown message types are logged and ignored; malformed messages close the connection.
• Reconcile before routable: the hub fails a reconnecting agent's jobs it does not list in known_jobs, and only then accepts jobs for that connection.
• The webhook never creates services; new services always start manual. The upsert does not touch update_mode.
• Auth: agents by token over pinned TLS; people by OIDC; CI by the UPDATER_API_KEY bearer token on POST /update only. Every state-changing UI request is a POST with a CSRF token.

Gotchas

• Image matching is case-sensitive. The tricky case is localhost:5000/foo:v1 where the first colon is a port, not a tag. See internal/imageref.
• Path safety uses filepath.Rel + ".." prefix check, NOT strings.HasPrefix. Prevents the /foo-evil vs /foo confusion. See internal/agent/updater/pathcheck.go.
• Go 1.26.3 (go.mod). Dockerfile pins golang:1.26-alpine. Bumping one without the other has caused a fix commit already.
• <summary> C# convention from global CLAUDE.md does not apply here — this is Go. Use idiomatic GoDoc (// FuncName does X.).
• Compose loads only one override file. Of compose.override.yml, compose.override.yaml, docker-compose.override.yml, docker-compose.override.yaml only the first that exists is read. Hence the refusal described above.
• Stacks started with explicit -f do not load the override on a manual up. The agent's own jobs always pass it explicitly.
• Override entries are never pruned. A service deleted from the stack file keeps its image: line in compose.override.yaml.
• There is no STACKS_ROOT. Stack directories must be mounted read-write at the host path (/path:/path), and SELF_ID must resolve to the agent's own container. On Docker Desktop/OrbStack bind sources are translated, so Compose jobs fail there.
• job.start carries no paths. The agent reads working dir and config files from its own Docker daemon at execution time.
• protocol.Service.ConfigFiles is the raw comma-joined label string, so Service stays comparable with == (inventory.Diff depends on it).
• Swarm "succeeded" means the daemon accepted the new spec, not that tasks converged.
• Swarm updates need manager-node API access for the agent doing the update.
• The image's default entrypoint is updater-agent. The master overrides it with updater-master.
• The webhook waits via a broker signal plus a store re-read, with a fallback poll (the broker drops signals for slow subscribers). Marking and starting jobs runs on context.WithoutCancel, so a client that disconnects cannot leave a queued job no agent knows about; only the waiting stops. The master never fails or cancels a timed-out job.
• A webhook job's target is <image_repo>:<request tag>, built from the service's own repo, never from the request's image string. With an explicit target the "follows no tag" refusal does not apply; removed, self, built and container still do.
• available_* is cleared by FinishJob on success only when the job's to_ref (as created, without @digest) equals available_ref and available_at <= job.created_at (that version is now running). A manual Update of the followed tag does not clear a badge for a different tag.
• Job output is capped at protocol.MaxJobOutput (128 KiB, tail). NUL bytes are stripped by the hub because Postgres text rejects them.

References

• Master/agent spec: docs/superpowers/specs/2026-10-12-master-agent-design.md (authoritative)
• Phase 1 plan: docs/superpowers/plans/2026-10-12-master-agent-phase-1-inventory.md
• Phase 2 plan: docs/superpowers/plans/2026-10-12-master-agent-phase-2-jobs.md
• Phase 3 plan: docs/superpowers/plans/2026-10-12-master-agent-phase-3-webhook.md
• Original single-instance design (historical): docs/superpowers/specs/2026-05-22-package-updater-design.md
• Consumer-side CI integration: gitea-action/ (calls the master's POST /update)

Conventions

• Conventional Commits (feat:, fix:, docs:, ci:, build:, chore:).
• One package = one responsibility; interfaces defined at consumer site (jobs.Store, jobs.Hub, conn.Jobs, hub.Store) for testability.
• Table-driven tests with stretchr/testify. No mocks beyond hand-written fakes.