windy-git/deploy/runner/docker-compose.yml

# CI runners (strand G7) — a SEPARATE compose project from the forge.
#
# Separate on purpose: runners restart, crash, get starved and get killed. None
# of that should ever touch the thing serving repositories. This is the cell
# doctrine applied one level down.
#
# ── I-5, and why there is a dind sidecar ───────────────────────────────────
#
# "CI never shares a kernel with identity. Runners execute untrusted code and
#  are isolated by machine boundary, not container boundary. No runner may hold
#  a credential scoped beyond its own job."
#
# act_runner needs a Docker daemon to start job containers. The tempting move is
# to mount the host's `/var/run/docker.sock`. That would hand every workflow —
# including whatever a transitive dependency's postinstall script feels like
# doing — the ability to start a privileged container mounting `/`, which is
# root on Veron 1. Every published act_runner example does exactly this.
#
# Instead the runner talks to its OWN daemon (`dind`). Untrusted job code runs
# as a child of that daemon, on an isolated network, with no route to the host
# socket and no route to the forge's database.
#
# The split that makes this work:
#   * `runner` is TRUSTED code (the act_runner daemon). It sits on the forge
#     network only so it can reach gitea:3000 to collect jobs.
#   * `dind` and every job container it spawns are UNTRUSTED. They are on a
#     private network with no access to the forge, its database, or its .env.
#
# dind itself is privileged — that is the cost, and it is the reason a job
# escape lands in a disposable daemon rather than on Grant's workstation.
#
# ⚠️ Do NOT "simplify" this by mounting the host docker socket.

name: windy-git-runner

services:
  dind:
    image: docker.io/library/docker:27-dind
    privileged: true
    environment:
      DOCKER_TLS_CERTDIR: ""   # plain TCP on an isolated network, no host route
    command: ["dockerd", "--host=tcp://0.0.0.0:2375", "--tls=false"]
    networks: [jobs]
    volumes:
      - dind-storage:/var/lib/docker
    # G1.5 — bounded so a fork-bomb workflow cannot starve Grant's interactive
    # session. Veron 1 is his workstation, not a dedicated build box.
    cpus: 12.0            # 12 of 24 cores
    mem_limit: 64g
    restart: unless-stopped

  # ── FOUR runners × capacity 1, not one runner × capacity 4 (2026-09-23) ──
  #
  # act caches every action repo at /root/.cache/act/<hash> INSIDE the runner
  # process and re-fetches it at the start of each job. With capacity 4, four
  # concurrent jobs share that one directory: one job's refresh rewrites it while
  # another is tarring it into its job container, and the job dies with
  # `lstat /root/.cache/act/<hash>/…: no such file or directory` on
  # `actions/setup-node` / `setup-uv` — a failure that reads like a broken
  # workflow. windy-chat (~20 jobs per push) hit it on 3 jobs in its first run.
  # `rm -rf /root/.cache/act` only reset the clock. Separate processes get
  # separate caches, so the race cannot occur. Same total parallelism, same
  # single capped dind — the blast radius is unchanged.
  runner: &runner
    # 0.2.11 -> 0.6.1 on 2026-08-14. The bundled act in 0.2.11 only knows
    # `runs.using: node12|node16|node20`, so ANY repo pinning a current action
    # major dies before its first step with "The runs.using key in action.yml
    # must be one of: [...], got node24" — Windy-Clone on actions/checkout@v5
    # is how this surfaced. Verified: `node24` is absent from the 0.2.11 binary
    # and present in 0.6.1. Every key in this directory's config.yaml still
    # exists in 0.6.1's schema (0.6.1 only ADDS keys), so the config carries
    # over unchanged. Rollback is re-pinning 0.2.11; the registration in the
    # runner-data volume survives either way.
    image: docker.io/gitea/act_runner:0.6.1
    depends_on: [dind]
    environment:
      # The runner reaches its OWN daemon. Never the host's.
      DOCKER_HOST: tcp://dind:2375
      # ⚠️ THE PUBLIC URL, deliberately — not http://gitea:3000.
      #
      # Job containers run inside the dind daemon's own private network, so they
      # cannot resolve `gitea`, which lives on the forge network. The first CI
      # run failed exactly here: "Could not resolve host: gitea".
      #
      # There were two ways out, and they are not equivalent:
      #   (a) put job containers on the forge network — untrusted workflow code
      #       would then sit one DNS name away from the forge's Postgres. This
      #       is the easy fix and it quietly repeals I-5.
      #   (b) send jobs to the PUBLIC forge surface, over the tunnel, exactly
      #       like any stranger on the internet. Untrusted code gets no private
      #       network route at all.
      #
      # (b) is strictly better and it is what this is. The cost is a hairpin —
      # container -> tunnel -> Cloudflare -> back to this box — plus Cloudflare's
      # ~100s proxy ceiling on any single fetch (G4A.5). For repos measured at
      # 0.63 GB of objects across 61 repos, with depth=1 checkouts, that ceiling
      # is nowhere near being a problem. Revisit if a model repo ever needs CI.
      GITEA_INSTANCE_URL: https://app.windygit.com
      GITEA_RUNNER_REGISTRATION_TOKEN: ${RUNNER_TOKEN:?set RUNNER_TOKEN}
      GITEA_RUNNER_NAME: veron-1
      CONFIG_FILE: /config.yaml
    volumes:
      - ./config.yaml:/config.yaml:ro
      - runner-data:/data
    # Only `jobs`. The runner no longer needs the forge network at all, because
    # it collects work over the public surface too — so there is now NO path
    # from any CI container to the forge's database. That is a better posture
    # than the one this file started with.
    networks: [jobs]
    cpus: 2.0
    mem_limit: 4g
    restart: unless-stopped

  # Each extra runner registers itself on first start (own name, own volume —
  # the registration lives in /data/.runner, so volumes must never be shared).
  runner-2:
    <<: *runner
    environment: &env2
      DOCKER_HOST: tcp://dind:2375
      GITEA_INSTANCE_URL: https://app.windygit.com
      GITEA_RUNNER_REGISTRATION_TOKEN: ${RUNNER_TOKEN:?set RUNNER_TOKEN}
      GITEA_RUNNER_NAME: veron-1-2
      CONFIG_FILE: /config.yaml
    volumes: [./config.yaml:/config.yaml:ro, runner-data-2:/data]
  runner-3:
    <<: *runner
    environment:
      <<: *env2
      GITEA_RUNNER_NAME: veron-1-3
    volumes: [./config.yaml:/config.yaml:ro, runner-data-3:/data]
  runner-4:
    <<: *runner
    environment:
      <<: *env2
      GITEA_RUNNER_NAME: veron-1-4
    volumes: [./config.yaml:/config.yaml:ro, runner-data-4:/data]

networks:
  jobs:
    # Untrusted job containers live here. No route to the forge.
    internal: false   # jobs legitimately need to fetch dependencies

volumes:
  dind-storage:
  runner-data:
  runner-data-2:
  runner-data-3:
  runner-data-4: