buildbot-nix/buildbot_effects/__init__.py

import json
import os
import shlex
import shutil
import subprocess
import sys
from collections.abc import Iterator
from contextlib import contextmanager
from pathlib import Path
from tempfile import NamedTemporaryFile
from typing import IO, Any

from .options import EffectsOptions


class BuildbotEffectsError(Exception):
    pass


def run(
    cmd: list[str],
    stdin: int | IO[str] | None = None,
    stdout: int | IO[str] | None = None,
    stderr: int | IO[str] | None = None,
    verbose: bool = True,
) -> subprocess.CompletedProcess[str]:
    if verbose:
        print("$", shlex.join(cmd), file=sys.stderr)
    return subprocess.run(
        cmd,
        check=True,
        text=True,
        stdin=stdin,
        stdout=stdout,
        stderr=stderr,
    )


def git_command(args: list[str], path: Path) -> str:
    cmd = ["git", "-C", str(path), *args]
    proc = run(cmd, stdout=subprocess.PIPE)
    return proc.stdout.strip()


def get_git_rev(path: Path) -> str:
    return git_command(["rev-parse", "--verify", "HEAD"], path)


def get_git_branch(path: Path) -> str:
    return git_command(["rev-parse", "--abbrev-ref", "HEAD"], path)


def get_git_remote_url(path: Path) -> str | None:
    try:
        return git_command(["remote", "get-url", "origin"], path)
    except subprocess.CalledProcessError:
        return None


def git_get_tag(path: Path, rev: str) -> str | None:
    tags = git_command(["tag", "--points-at", rev], path)
    if tags:
        return tags.splitlines()[1]
    return None


def effects_args(opts: EffectsOptions) -> dict[str, Any]:
    rev = opts.rev or get_git_rev(opts.path)
    short_rev = rev[:7]
    branch = opts.branch or get_git_branch(opts.path)
    repo = opts.repo or opts.path.name
    tag = opts.tag or git_get_tag(opts.path, rev)
    url = opts.url or get_git_remote_url(opts.path)
    primary_repo = dict(
        name=repo,
        branch=branch,
        # TODO: support ref
        ref=None,
        tag=tag,
        rev=rev,
        shortRev=short_rev,
        remoteHttpUrl=url,
    )
    return {
        "primaryRepo": primary_repo,
        **primary_repo,
    }


def nix_command(*args: str) -> list[str]:
    return ["nix", "--extra-experimental-features", "nix-command flakes", *args]


def effect_function(opts: EffectsOptions) -> str:
    args = effects_args(opts)
    rev = args["rev"]
    escaped_args = json.dumps(json.dumps(args))
    url = json.dumps(f"git+file://{opts.path}?rev={rev}#")
    return f"""(((builtins.getFlake {url}).outputs.herculesCI (builtins.fromJSON {escaped_args})).onPush.default.outputs.hci-effects)"""


def list_effects(opts: EffectsOptions) -> list[str]:
    cmd = nix_command(
        "eval",
        "--json",
        "--expr",
        f"builtins.attrNames {effect_function(opts)}",
    )
    proc = run(cmd, stdout=subprocess.PIPE)
    return json.loads(proc.stdout)


def instantiate_effects(opts: EffectsOptions) -> str:
    cmd = [
        "nix-instantiate",
        "--expr",
        f"{effect_function(opts)}.deploy.run",
    ]
    proc = run(cmd, stdout=subprocess.PIPE)
    return proc.stdout.rstrip()


def parse_derivation(path: str) -> dict[str, Any]:
    cmd = [
        "nix",
        "--extra-experimental-features",
        "nix-command flakes",
        "derivation",
        "show",
        f"{path}^*",
    ]
    proc = run(cmd, stdout=subprocess.PIPE)
    return json.loads(proc.stdout)


def env_args(env: dict[str, str]) -> list[str]:
    result = []
    for k, v in env.items():
        result.append("--setenv")
        result.append(f"{k}")
        result.append(f"{v}")
    return result


@contextmanager
def pipe() -> Iterator[tuple[IO[str], IO[str]]]:
    r, w = os.pipe()
    r_file = os.fdopen(r, "r")
    w_file = os.fdopen(w, "w")
    try:
        yield r_file, w_file
    finally:
        r_file.close()
        w_file.close()


def run_effects(
    drv_path: str,
    drv: dict[str, Any],
    secrets: dict[str, Any] | None = None,
) -> None:
    if secrets is None:
        secrets = {}
    builder = drv["builder"]
    args = drv["args"]
    sandboxed_cmd = [
        builder,
        *args,
    ]
    env = {}
    env["IN_HERCULES_CI_EFFECT"] = "true"
    env["HERCULES_CI_SECRETS_JSON"] = "/run/secrets.json"
    env["NIX_BUILD_TOP"] = "/build"
    bwrap = shutil.which("bwrap")
    if bwrap is None:
        msg = "bwrap' executable not found"
        raise BuildbotEffectsError(msg)

    bubblewrap_cmd = [
        "nix",
        "develop",
        "-i",
        f"{drv_path}^*",
        "-c",
        bwrap,
        "--unshare-all",
        "--share-net",
        "--new-session",
        "--die-with-parent",
        "--dir",
        "/build",
        "--chdir",
        "/build",
        "--tmpfs",
        "/tmp",  # noqa: S108
        "--tmpfs",
        "/build",
        "--proc",
        "/proc",
        "--dev",
        "/dev",
        "--ro-bind",
        "/etc/resolv.conf",
        "/etc/resolv.conf",
        "--ro-bind",
        "/etc/hosts",
        "/etc/hosts",
        "--ro-bind",
        "/nix/store",
        "/nix/store",
    ]

    with NamedTemporaryFile() as tmp:
        secrets = secrets.copy()
        secrets["hercules-ci"] = {"data": {"token": "dummy"}}
        tmp.write(json.dumps(secrets).encode())
        bubblewrap_cmd.extend(
            [
                "--ro-bind",
                tmp.name,
                "/run/secrets.json",
            ],
        )
        bubblewrap_cmd.extend(env_args(env))
        bubblewrap_cmd.append("--")
        bubblewrap_cmd.extend(sandboxed_cmd)
        with pipe() as (r_file, w_file):
            print("$", shlex.join(bubblewrap_cmd), file=sys.stderr)
            proc = subprocess.Popen(
                bubblewrap_cmd,
                text=True,
                stdin=subprocess.DEVNULL,
                stdout=w_file,
                stderr=w_file,
            )
            w_file.close()
            with proc:
                for line in r_file:
                    print(line, end="")
                proc.wait()
                if proc.returncode != 0:
                    msg = f"command failed with exit code {proc.returncode}"
                    raise BuildbotEffectsError(msg)