buildbot-nix/buildbot_nix/worker.py

import multiprocessing
import os
import socket
from dataclasses import dataclass, field
from pathlib import Path

from buildbot_worker.bot import Worker
from twisted.application import service
from twisted.python import components


def require_env(key: str) -> str:
    val = os.environ.get(key)
    assert val is not None, f"{key} environment variable is not set"
    return val


@dataclass
class WorkerConfig:
    password: str = field(
        default_factory=lambda: Path(require_env("WORKER_PASSWORD_FILE"))
        .read_text()
        .rstrip("\r\n")
    )
    worker_name: str = field(
        default_factory=lambda: os.environ.get("WORKER_NAME", socket.gethostname())
    )
    worker_count: int = int(
        os.environ.get("WORKER_COUNT", str(multiprocessing.cpu_count())),
    )
    buildbot_dir: Path = field(
        default_factory=lambda: Path(require_env("BUILDBOT_DIR"))
    )
    master_url: str = field(default_factory=lambda: require_env("MASTER_URL"))


def setup_worker(
    application: components.Componentized,
    builder_id: int,
    config: WorkerConfig,
) -> None:
    basedir = config.buildbot_dir.parent / f"{config.buildbot_dir.name}-{builder_id:03}"
    basedir.mkdir(parents=True, exist_ok=True, mode=0o700)

    workername = f"{config.worker_name}-{builder_id:03}"
    keepalive = 600
    umask = None
    maxdelay = 300
    numcpus = None
    allow_shutdown = None

    print(f"Starting worker {workername}")
    s = Worker(
        None,
        None,
        workername,
        config.password,
        str(basedir),
        keepalive,
        connection_string=config.master_url,
        umask=umask,
        maxdelay=maxdelay,
        numcpus=numcpus,
        allow_shutdown=allow_shutdown,
    )
    # defaults to 4096, bump to 10MB for nix-eval-jobs
    s.bot.max_line_length = 10485760
    s.setServiceParent(application)


def setup_workers(application: components.Componentized, config: WorkerConfig) -> None:
    for i in range(config.worker_count):
        setup_worker(application, i, config)


# note: this line is matched against to check that this is a worker
# directory; do not edit it.
application = service.Application("buildbot-worker")  # type: ignore[no-untyped-call]
setup_workers(application, WorkerConfig())