buildbot-nix/buildbot_nix/__init__.py

#!/usr/bin/env python3

import json
import multiprocessing
import os
import signal
import sys
import uuid
from collections import defaultdict
from collections.abc import Generator
from dataclasses import dataclass
from pathlib import Path
from typing import Any

from buildbot.configurators import ConfiguratorBase
from buildbot.plugins import reporters, schedulers, secrets, steps, util, worker
from buildbot.process import buildstep, logobserver, remotecommand
from buildbot.process.log import Log
from buildbot.process.project import Project
from buildbot.process.properties import Interpolate, Properties
from buildbot.process.results import ALL_RESULTS, statusToString
from buildbot.steps.trigger import Trigger
from buildbot.util import asyncSleep
from twisted.internet import defer, threads
from twisted.python.failure import Failure

from .github_projects import (
    GithubProject,
    create_project_hook,  # noqa: E402
    load_projects,
    refresh_projects,
    slugify_project_name,
)

SKIPPED_BUILDER_NAME = "skipped-builds"


class BuildTrigger(Trigger):
    """
    Dynamic trigger that creates a build for every attribute.
    """

    def __init__(
        self,
        builds_scheduler: str,
        skipped_builds_scheduler: str,
        jobs: list[dict[str, Any]],
        **kwargs: Any,
    ) -> None:
        if "name" not in kwargs:
            kwargs["name"] = "trigger"
        self.jobs = jobs
        self.config = None
        self.builds_scheduler = builds_scheduler
        self.skipped_builds_scheduler = skipped_builds_scheduler
        Trigger.__init__(
            self,
            waitForFinish=True,
            schedulerNames=[builds_scheduler, skipped_builds_scheduler],
            haltOnFailure=True,
            flunkOnFailure=True,
            sourceStamps=[],
            alwaysUseLatest=False,
            updateSourceStamp=False,
            **kwargs,
        )

    def createTriggerProperties(self, props: Any) -> Any:  # noqa: N802
        return props

    def getSchedulersAndProperties(self) -> list[tuple[str, Properties]]:  # noqa: N802
        build_props = self.build.getProperties()
        repo_name = build_props.getProperty(
            "github.base.repo.full_name",
            build_props.getProperty("github.repository.full_name"),
        )
        project_id = slugify_project_name(repo_name)
        source = f"nix-eval-{project_id}"

        triggered_schedulers = []
        for job in self.jobs:
            attr = job.get("attr", "eval-error")
            name = attr
            if repo_name is not None:
                name = f"github:{repo_name}#checks.{name}"
            else:
                name = f"checks.{name}"
            error = job.get("error")
            props = Properties()
            props.setProperty("virtual_builder_name", name, source)
            props.setProperty("status_name", f"nix-build .#checks.{attr}", source)
            props.setProperty("virtual_builder_tags", "", source)

            if error is not None:
                props.setProperty("error", error, source)
                triggered_schedulers.append((self.skipped_builds_scheduler, props))
                continue

            if job.get("isCached"):
                triggered_schedulers.append((self.skipped_builds_scheduler, props))
                continue

            drv_path = job.get("drvPath")
            system = job.get("system")
            out_path = job.get("outputs", {}).get("out")

            build_props.setProperty(f"{attr}-out_path", out_path, source)
            build_props.setProperty(f"{attr}-drv_path", drv_path, source)

            props.setProperty("attr", attr, source)
            props.setProperty("system", system, source)
            props.setProperty("drv_path", drv_path, source)
            props.setProperty("out_path", out_path, source)
            # we use this to identify builds when running a retry
            props.setProperty("build_uuid", str(uuid.uuid4()), source)

            triggered_schedulers.append((self.builds_scheduler, props))
        return triggered_schedulers

    def getCurrentSummary(self) -> dict[str, str]:  # noqa: N802
        """
        The original build trigger will the generic builder name `nix-build` in this case, which is not helpful
        """
        if not self.triggeredNames:
            return {"step": "running"}
        summary = []
        if self._result_list:
            for status in ALL_RESULTS:
                count = self._result_list.count(status)
                if count:
                    summary.append(
                        f"{self._result_list.count(status)} {statusToString(status, count)}"
                    )
        return {"step": f"({', '.join(summary)})"}


class NixEvalCommand(buildstep.ShellMixin, steps.BuildStep):
    """
    Parses the output of `nix-eval-jobs` and triggers a `nix-build` build for
    every attribute.
    """

    def __init__(self, supported_systems: list[str], **kwargs: Any) -> None:
        kwargs = self.setupShellMixin(kwargs)
        super().__init__(**kwargs)
        self.observer = logobserver.BufferLogObserver()
        self.addLogObserver("stdio", self.observer)
        self.supported_systems = supported_systems

    @defer.inlineCallbacks
    def run(self) -> Generator[Any, object, Any]:
        # run nix-eval-jobs --flake .#checks to generate the dict of stages
        cmd: remotecommand.RemoteCommand = yield self.makeRemoteShellCommand()
        yield self.runCommand(cmd)

        # if the command passes extract the list of stages
        result = cmd.results()
        if result == util.SUCCESS:
            # create a ShellCommand for each stage and add them to the build
            jobs = []

            for line in self.observer.getStdout().split("\n"):
                if line != "":
                    try:
                        job = json.loads(line)
                    except json.JSONDecodeError as e:
                        raise Exception(f"Failed to parse line: {line}") from e
                    jobs.append(job)
            build_props = self.build.getProperties()
            repo_name = build_props.getProperty(
                "github.base.repo.full_name",
                build_props.getProperty("github.repository.full_name"),
            )
            project_id = slugify_project_name(repo_name)
            filtered_jobs = []
            for job in jobs:
                system = job.get("system")
                if not system:  # report eval errors
                    filtered_jobs.append(job)
                elif system in self.supported_systems:
                    filtered_jobs.append(job)

            self.build.addStepsAfterCurrentStep(
                [
                    BuildTrigger(
                        builds_scheduler=f"{project_id}-nix-build",
                        skipped_builds_scheduler=f"{project_id}-nix-skipped-build",
                        name="build flake",
                        jobs=filtered_jobs,
                    )
                ]
            )

        return result


# FIXME this leaks memory... but probably not enough that we care
class RetryCounter:
    def __init__(self, retries: int) -> None:
        self.builds: dict[uuid.UUID, int] = defaultdict(lambda: retries)

    def retry_build(self, id: uuid.UUID) -> int:
        retries = self.builds[id]
        if retries > 1:
            self.builds[id] = retries - 1
            return retries
        else:
            return 0


# For now we limit this to two. Often this allows us to make the error log
# shorter because we won't see the logs for all previous succeeded builds
RETRY_COUNTER = RetryCounter(retries=2)


class EvalErrorStep(steps.BuildStep):
    """
    Shows the error message of a failed evaluation.
    """

    @defer.inlineCallbacks
    def run(self) -> Generator[Any, object, Any]:
        error = self.getProperty("error")
        attr = self.getProperty("attr")
        # show eval error
        error_log: Log = yield self.addLog("nix_error")
        error_log.addStderr(f"{attr} failed to evaluate:\n{error}")
        return util.FAILURE


class NixBuildCommand(buildstep.ShellMixin, steps.BuildStep):
    """
    Builds a nix derivation.
    """

    def __init__(self, **kwargs: Any) -> None:
        kwargs = self.setupShellMixin(kwargs)
        super().__init__(**kwargs)

    @defer.inlineCallbacks
    def run(self) -> Generator[Any, object, Any]:
        # run `nix build`
        cmd: remotecommand.RemoteCommand = yield self.makeRemoteShellCommand()
        yield self.runCommand(cmd)

        res = cmd.results()
        if res == util.FAILURE:
            retries = RETRY_COUNTER.retry_build(self.getProperty("build_uuid"))
            if retries > 0:
                return util.RETRY
        return res


class UpdateBuildOutput(steps.BuildStep):
    """
    Updates store paths in a public www directory.
    This is useful to prefetch updates without having to evaluate
    on the target machine.
    """

    def __init__(self, path: Path, **kwargs: Any) -> None:
        super().__init__(**kwargs)
        self.path = path

    def run(self) -> Generator[Any, object, Any]:
        props = self.build.getProperties()
        if props.getProperty("branch") != props.getProperty(
            "github.repository.default_branch"
        ):
            return util.SKIPPED

        attr = os.path.basename(props.getProperty("attr"))
        out_path = props.getProperty("out_path")
        # XXX don't hardcode this
        self.path.mkdir(parents=True, exist_ok=True)
        (self.path / attr).write_text(out_path)
        return util.SUCCESS


class ReloadGithubProjects(steps.BuildStep):
    name = "reload_github_projects"

    def __init__(self, token: str, project_cache_file: Path, **kwargs: Any) -> None:
        self.token = token
        self.project_cache_file = project_cache_file
        super().__init__(**kwargs)

    def reload_projects(self) -> None:
        refresh_projects(self.token, self.project_cache_file)

    @defer.inlineCallbacks
    def run(self) -> Generator[Any, object, Any]:
        d = threads.deferToThread(self.reload_projects)

        self.error_msg = ""

        def error_cb(failure: Failure) -> int:
            self.error_msg += failure.getTraceback()
            return util.FAILURE

        d.addCallbacks(lambda _: util.SUCCESS, error_cb)
        res = yield d
        if res == util.SUCCESS:
            # reload the buildbot config
            os.kill(os.getpid(), signal.SIGHUP)
            return util.SUCCESS
        else:
            log: Log = yield self.addLog("log")
            log.addStderr(f"Failed to reload project list: {self.error_msg}")
            return util.FAILURE


def reload_github_projects(
    worker_names: list[str],
    github_token_secret: str,
    project_cache_file: Path,
) -> util.BuilderConfig:
    """
    Updates the flake an opens a PR for it.
    """
    factory = util.BuildFactory()
    factory.addStep(
        ReloadGithubProjects(github_token_secret, project_cache_file=project_cache_file)
    )
    return util.BuilderConfig(
        name="reload-github-projects",
        workernames=worker_names,
        factory=factory,
    )


# The builtin retry mechanism doesn't seem to work for github,
# since github is sometimes not delivering the pull request ref fast enough.
class GitWithRetry(steps.Git):
    @defer.inlineCallbacks
    def run_vc(
        self, branch: str, revision: str, patch: str
    ) -> Generator[Any, object, Any]:
        retry_counter = 0
        while True:
            try:
                res = yield super().run_vc(branch, revision, patch)
                return res
            except Exception as e:
                retry_counter += 1
                if retry_counter == 3:
                    raise e
                log: Log = yield self.addLog("log")
                yield log.addStderr(f"Retrying git clone (error: {e})\n")
                yield asyncSleep(2 << retry_counter)  # 2, 4, 8


def nix_eval_config(
    project: GithubProject,
    worker_names: list[str],
    github_token_secret: str,
    supported_systems: list[str],
    eval_lock: util.WorkerLock,
    worker_count: int,
    max_memory_size: int,
) -> util.BuilderConfig:
    """
    Uses nix-eval-jobs to evaluate hydraJobs from flake.nix in parallel.
    For each evaluated attribute a new build pipeline is started.
    """
    factory = util.BuildFactory()
    # check out the source
    url_with_secret = util.Interpolate(
        f"https://git:%(secret:{github_token_secret})s@github.com/%(prop:project)s"
    )
    factory.addStep(
        GitWithRetry(
            repourl=url_with_secret,
            method="clean",
            submodules=True,
            haltOnFailure=True,
        )
    )

    factory.addStep(
        NixEvalCommand(
            env={},
            name="evaluate flake",
            supported_systems=supported_systems,
            command=[
                "nix-eval-jobs",
                "--workers",
                str(worker_count),
                "--max-memory-size",
                str(max_memory_size),
                "--option",
                "accept-flake-config",
                "true",
                "--gc-roots-dir",
                # FIXME: don't hardcode this
                "/var/lib/buildbot-worker/gcroot",
                "--force-recurse",
                "--check-cache-status",
                "--flake",
                ".#checks",
            ],
            haltOnFailure=True,
            locks=[eval_lock.access("exclusive")],
        )
    )

    return util.BuilderConfig(
        name=f"{project.name}/nix-eval",
        workernames=worker_names,
        project=project.name,
        factory=factory,
        properties=dict(status_name="nix-eval"),
    )


def nix_build_config(
    project: GithubProject,
    worker_names: list[str],
    has_cachix_auth_token: bool = False,
    has_cachix_signing_key: bool = False,
    outputs_path: Path | None = None,
) -> util.BuilderConfig:
    """
    Builds one nix flake attribute.
    """
    factory = util.BuildFactory()
    factory.addStep(
        NixBuildCommand(
            env={},
            name="Build flake attr",
            command=[
                "nix",
                "build",
                "-L",
                "--option",
                "keep-going",
                "true",
                "--accept-flake-config",
                "--out-link",
                util.Interpolate("result-%(prop:attr)s"),
                util.Interpolate("%(prop:drv_path)s^*"),
            ],
            haltOnFailure=True,
        )
    )
    if has_cachix_auth_token or has_cachix_signing_key:
        if has_cachix_signing_key:
            env = dict(CACHIX_SIGNING_KEY=util.Secret("cachix-signing-key"))
        else:
            env = dict(CACHIX_AUTH_TOKEN=util.Secret("cachix-auth-token"))
        factory.addStep(
            steps.ShellCommand(
                name="Upload cachix",
                env=env,
                command=[
                    "cachix",
                    "push",
                    util.Secret("cachix-name"),
                    util.Interpolate("result-%(prop:attr)s"),
                ],
            )
        )

    factory.addStep(
        steps.ShellCommand(
            name="Register gcroot",
            command=[
                "nix-store",
                "--add-root",
                # FIXME: cleanup old build attributes
                util.Interpolate(
                    "/nix/var/nix/gcroots/per-user/buildbot-worker/%(prop:project)s/%(prop:attr)s"
                ),
                "-r",
                util.Property("out_path"),
            ],
            doStepIf=lambda s: s.getProperty("branch")
            == s.getProperty("github.repository.default_branch"),
        )
    )
    factory.addStep(
        steps.ShellCommand(
            name="Delete temporary gcroots",
            command=["rm", "-f", util.Interpolate("result-%(prop:attr)s")],
        )
    )
    if outputs_path is not None:
        factory.addStep(
            UpdateBuildOutput(
                name="Update build output",
                path=outputs_path,
            )
        )
    return util.BuilderConfig(
        name=f"{project.name}/nix-build",
        project=project.name,
        workernames=worker_names,
        collapseRequests=False,
        env={},
        factory=factory,
    )


def nix_skipped_build_config(
    project: GithubProject, worker_names: list[str]
) -> util.BuilderConfig:
    """
    Dummy builder that is triggered when a build is skipped.
    """
    factory = util.BuildFactory()
    factory.addStep(
        EvalErrorStep(
            name="Nix evaluation",
            doStepIf=lambda s: s.getProperty("error"),
            hideStepIf=lambda _, s: not s.getProperty("error"),
        )
    )

    # This is just a dummy step showing the cached build
    factory.addStep(
        steps.BuildStep(
            name="Nix build (cached)",
            doStepIf=lambda _: False,
            hideStepIf=lambda _, s: s.getProperty("error"),
        )
    )
    return util.BuilderConfig(
        name=f"{project.name}/nix-skipped-build",
        project=project.name,
        workernames=worker_names,
        collapseRequests=False,
        env={},
        factory=factory,
    )


def read_secret_file(secret_name: str) -> str:
    directory = os.environ.get("CREDENTIALS_DIRECTORY")
    if directory is None:
        print("directory not set", file=sys.stderr)
        sys.exit(1)
    return Path(directory).joinpath(secret_name).read_text().rstrip()


@dataclass
class GithubConfig:
    oauth_id: str
    admins: list[str]
    buildbot_user: str
    oauth_secret_name: str = "github-oauth-secret"
    webhook_secret_name: str = "github-webhook-secret"
    token_secret_name: str = "github-token"
    project_cache_file: Path = Path("github-project-cache.json")
    topic: str | None = "build-with-buildbot"

    def token(self) -> str:
        return read_secret_file(self.token_secret_name)


def config_for_project(
    config: dict[str, Any],
    project: GithubProject,
    credentials: str,
    worker_names: list[str],
    github: GithubConfig,
    nix_supported_systems: list[str],
    nix_eval_worker_count: int,
    nix_eval_max_memory_size: int,
    eval_lock: util.WorkerLock,
    outputs_path: Path | None = None,
) -> Project:
    config["projects"].append(Project(project.name))
    config["schedulers"].extend(
        [
            schedulers.SingleBranchScheduler(
                name=f"{project.id}-default-branch",
                change_filter=util.ChangeFilter(
                    repository=project.url,
                    filter_fn=lambda c: c.branch
                    == c.properties.getProperty("github.repository.default_branch"),
                ),
                builderNames=[f"{project.name}/nix-eval"],
                treeStableTimer=5,
            ),
            # this is compatible with bors or github's merge queue
            schedulers.SingleBranchScheduler(
                name=f"{project.id}-merge-queue",
                change_filter=util.ChangeFilter(
                    repository=project.url,
                    branch_re="(gh-readonly-queue/.*|staging|trying)",
                ),
                builderNames=[f"{project.name}/nix-eval"],
            ),
            # build all pull requests
            schedulers.SingleBranchScheduler(
                name=f"{project.id}-prs",
                change_filter=util.ChangeFilter(
                    repository=project.url, category="pull"
                ),
                builderNames=[f"{project.name}/nix-eval"],
            ),
            # this is triggered from `nix-eval`
            schedulers.Triggerable(
                name=f"{project.id}-nix-build",
                builderNames=[f"{project.name}/nix-build"],
            ),
            # this is triggered from `nix-eval` when the build is skipped
            schedulers.Triggerable(
                name=f"{project.id}-nix-skipped-build",
                builderNames=[f"{project.name}/nix-skipped-build"],
            ),
            # allow to manually trigger a nix-build
            schedulers.ForceScheduler(
                name=f"{project.id}-force",
                builderNames=[f"{project.name}/nix-eval"],
                properties=[
                    util.StringParameter(
                        name="project",
                        label="Name of the GitHub repository.",
                        default=project.name,
                    )
                ],
            ),
        ]
    )
    has_cachix_auth_token = os.path.isfile(
        os.path.join(credentials, "cachix-auth-token")
    )
    has_cachix_signing_key = os.path.isfile(
        os.path.join(credentials, "cachix-signing-key")
    )
    config["builders"].extend(
        [
            # Since all workers run on the same machine, we only assign one of them to do the evaluation.
            # This should prevent exessive memory usage.
            nix_eval_config(
                project,
                [worker_names[0]],
                github_token_secret=github.token_secret_name,
                supported_systems=nix_supported_systems,
                worker_count=nix_eval_worker_count,
                max_memory_size=nix_eval_max_memory_size,
                eval_lock=eval_lock,
            ),
            nix_build_config(
                project,
                worker_names,
                has_cachix_auth_token,
                has_cachix_signing_key,
                outputs_path=outputs_path,
            ),
            nix_skipped_build_config(project, [SKIPPED_BUILDER_NAME]),
        ]
    )


class NixConfigurator(ConfiguratorBase):
    """Janitor is a configurator which create a Janitor Builder with all needed Janitor steps"""

    def __init__(
        self,
        # Shape of this file:
        # [ { "name": "<worker-name>", "pass": "<worker-password>", "cores": "<cpu-cores>" } ]
        github: GithubConfig,
        url: str,
        nix_supported_systems: list[str],
        nix_eval_worker_count: int | None,
        nix_eval_max_memory_size: int,
        nix_workers_secret_name: str = "buildbot-nix-workers",
        outputs_path: str | None = None,
    ) -> None:
        super().__init__()
        self.nix_workers_secret_name = nix_workers_secret_name
        self.nix_eval_max_memory_size = nix_eval_max_memory_size
        self.nix_eval_worker_count = nix_eval_worker_count
        self.nix_supported_systems = nix_supported_systems
        self.github = github
        self.url = url
        self.systemd_credentials_dir = os.environ["CREDENTIALS_DIRECTORY"]
        if outputs_path is None:
            self.outputs_path = None
        else:
            self.outputs_path = Path(outputs_path)

    def configure(self, config: dict[str, Any]) -> None:
        projects = load_projects(self.github.token(), self.github.project_cache_file)
        if self.github.topic is not None:
            projects = [p for p in projects if self.github.topic in p.topics]
        worker_config = json.loads(read_secret_file(self.nix_workers_secret_name))
        worker_names = []

        config.setdefault("projects", [])
        config.setdefault("secretsProviders", [])
        config.setdefault("www", {})

        for item in worker_config:
            cores = item.get("cores", 0)
            for i in range(cores):
                worker_name = f"{item['name']}-{i:03}"
                config["workers"].append(worker.Worker(worker_name, item["pass"]))
                worker_names.append(worker_name)

        webhook_secret = read_secret_file(self.github.webhook_secret_name)
        eval_lock = util.WorkerLock("nix-eval")

        for project in projects:
            create_project_hook(
                project.owner,
                project.repo,
                self.github.token(),
                self.url + "change_hook/github",
                webhook_secret,
            )
            config_for_project(
                config,
                project,
                self.systemd_credentials_dir,
                worker_names,
                self.github,
                self.nix_supported_systems,
                self.nix_eval_worker_count or multiprocessing.cpu_count(),
                self.nix_eval_max_memory_size,
                eval_lock,
                self.outputs_path,
            )

        # Reload github projects
        config["builders"].append(
            reload_github_projects(
                [worker_names[0]],
                self.github.token(),
                self.github.project_cache_file,
            )
        )
        config["workers"].append(worker.LocalWorker(SKIPPED_BUILDER_NAME))
        config["schedulers"].extend(
            [
                schedulers.ForceScheduler(
                    name="reload-github-projects",
                    builderNames=["reload-github-projects"],
                    buttonName="Update projects",
                ),
                # project list twice a day
                schedulers.Periodic(
                    name="reload-github-projects-bidaily",
                    builderNames=["reload-github-projects"],
                    periodicBuildTimer=12 * 60 * 60,
                ),
            ]
        )
        config["services"].append(
            reporters.GitHubStatusPush(
                token=self.github.token(),
                # Since we dynamically create build steps,
                # we use `virtual_builder_name` in the webinterface
                # so that we distinguish what has beeing build
                context=Interpolate("buildbot/%(prop:status_name)s"),
            )
        )
        systemd_secrets = secrets.SecretInAFile(
            dirname=os.environ["CREDENTIALS_DIRECTORY"]
        )
        config["secretsProviders"].append(systemd_secrets)
        config["www"]["change_hook_dialects"] = config["www"].get(
            "change_hook_dialects", {}
        )
        config["www"]["change_hook_dialects"]["github"] = {
            "secret": webhook_secret,
            "strict": True,
            "token": self.github.token(),
            "github_property_whitelist": "*",
        }

        if not config["www"].get("auth"):
            config["www"]["avatar_methods"] = config["www"].get("avatar_methods", [])
            config["www"]["avatar_methods"].append(
                util.AvatarGitHub(token=self.github.token())
            )
            config["www"]["auth"] = util.GitHubAuth(
                self.github.oauth_id, read_secret_file(self.github.oauth_secret_name)
            )
            config["www"]["authz"] = util.Authz(
                roleMatchers=[
                    util.RolesFromUsername(
                        roles=["admin"], usernames=self.github.admins
                    )
                ],
                allowRules=[
                    util.AnyEndpointMatcher(role="admin", defaultDeny=False),
                    util.AnyControlEndpointMatcher(role="admins"),
                ],
            )