MechaCat02 dea776b2a3 feat(orchestrator-core): ExecutionGate + 503/Retry-After on overflow
Adds a single global concurrency cap on the data-plane dispatch path:

  - orchestrator-core::gate::ExecutionGate wraps tokio::Semaphore.
    Non-blocking try_acquire — no queue. PICLOUD_MAX_CONCURRENT_EXECUTIONS
    env var (default 32) sets the cap.
  - LocalExecutorClient acquires a permit before spawn_blocking; the
    permit drops with the future so the slot returns automatically.
  - On refusal, ExecError::Overloaded { retry_after_secs: 1 } surfaces
    upward. ApiError::IntoResponse already maps that to 503 with a
    Retry-After header (landed in the previous commit alongside the
    variant itself).
  - picloud binary constructs the gate once at build_app and shares it
    with LocalExecutorClient.

The cap exists so a Rhai script storm can't drain the blocking-thread
pool — pushing back hard beats letting requests pile up against a
finite worker count. Per-app / per-script caps stay deferred until a
real workload demands them.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-30 18:50:44 +02:00

PiCloud

A lightweight, self-hosted, event-driven serverless compute platform. Upload a Rhai script, get an HTTP endpoint. Designed to run on a single modest server with no idle CPU cost, and to scale out to a small cluster when you need it.

Status: Phase 1 — MVP scaffolding in progress.

The authoritative design lives in serverless_cloud_blueprint.md.

Why

Existing serverless platforms are either cloud-locked, heavyweight, or both. PiCloud aims for the opposite end of the spectrum: one binary, one database, one reverse proxy — running on hardware you already own.

Architecture (one paragraph)

PiCloud splits into three logical services — manager (control plane: scripts, schedules, dashboard), orchestrator (per-node event ingress and dispatch), and executor (per-node Rhai sandbox) — each backed by a *-core Rust library. In MVP they run in a single process; in cluster mode they run as three binaries with one manager and one orchestrator + executor per node. Caddy fronts everything; PostgreSQL is the single source of truth.

See CLAUDE.md for working notes and serverless_cloud_blueprint.md for the full design.

Quick Start

Coming as scaffolding lands. For now:

# Rust toolchain (pinned via rust-toolchain.toml)
cargo check --workspace

# Run the all-in-one MVP binary (once main.rs is wired up)
cargo run -p picloud

Repository Layout

crates/
  shared/                 cross-cutting types
  executor-core/          Rhai engine + sandbox
  orchestrator-core/      event ingress, dispatch
  manager-core/           control plane
  picloud/                MVP all-in-one binary
  picloud-{manager,orchestrator,executor}/   cluster-mode binaries (skeleton)
dashboard/                SvelteKit
caddy/                    Caddyfile
docker/                   Dockerfiles
docs/
  git-workflow.md         Trunk-based workflow

Contributing

See docs/git-workflow.md for the branching and commit conventions. TL;DR: trunk-based, short-lived branches, Conventional Commits, no force-pushing main.

License

TBD.

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