woodpecker-in-a-vm/index.js

import { nanoid } from "nanoid";
import { execFile as execFileCallback } from "node:child_process";
import {
  constants,
  copyFile,
  mkdir,
  opendir,
  readFile,
  readdir,
  rm,
  symlink,
  writeFile,
} from "node:fs/promises";
import { tmpdir } from "node:os";
import { basename, join } from "node:path";
import { promisify } from "node:util";
import { init } from "@nulo/apkit";
import * as dotenv from "dotenv";
dotenv.config({ override: true });

const execFile = promisify(execFileCallback);

// TODO: configurar runsc

const currRootPath = await setupRootfsDir();
const alpine = await init(currRootPath);
await alpine.install(["alpine-base", "fish", "docker", "linux-virt"]);
await alpine.rcUpdate("sysinit", "networking");
await alpine.rcUpdate("boot", "docker");
await alpine.rcUpdate("boot", "mdev");
await alpine.rcUpdate("default", "ntpd");
await alpine.rcUpdate("default", "local");

/**
 * @param {string} path
 * @param {((file: string) => string) | ((file: string) => Promise<string>)} patchFunc
 * @returns {Promise<void>}
 */
async function patchFile(path, patchFunc) {
  let file = await readFile(path, "utf-8");
  file = await patchFunc(file);
  await writeFile(path, file);
}

await patchFile(
  join(currRootPath, "/etc/modprobe.d/blacklist.conf"),
  (blacklist) => blacklist.replace("tiny_power_button", "button")
);
await patchFile(
  join(currRootPath, "/etc/rc.conf"),
  (rc) => rc + '\nrc_cgroup_mode="unified"\n'
);

await writeFile(
  "interfaces",
  `auto lo
iface lo inet loopback
  
auto eth0
iface eth0
    use dhcp`,
  { mode: 0o600 }
);
await execFile("sudo", [
  "mv",
  "interfaces",
  join(currRootPath, "/etc/network/interfaces"),
]);
await execFile("sudo", [
  "chown",
  "0:0",
  join(currRootPath, "/etc/network/interfaces"),
]);

const woodpeckerServer = getConfig("WOODPECKER_SERVER");
const woodpeckerAgentSecret = getConfig("WOODPECKER_AGENT_SECRET");

await writeFile(
  "woodpecker.start",
  `#!/bin/sh

modprobe tiny-power-button
  
while ! docker pull docker.io/woodpeckerci/woodpecker-agent:latest; do
  sleep 1
done
exec docker run --detach --rm \
	--name=woodpecker-agent \
	-v /var/run/docker.sock:/var/run/docker.sock \
	-e WOODPECKER_SERVER='${woodpeckerServer}' \
	-e WOODPECKER_AGENT_SECRET='${woodpeckerAgentSecret}' \
	-e WOODPECKER_MAX_PROCS=8 \
	docker.io/woodpeckerci/woodpecker-agent:latest \
	agent`,
  { mode: 0o700 }
);
await execFile("sudo", [
  "mv",
  "woodpecker.start",
  join(currRootPath, "/etc/local.d/woodpecker.start"),
]);
await execFile("sudo", [
  "chown",
  "0:0",
  join(currRootPath, "/etc/local.d/woodpecker.start"),
]);

await alpine.rcUpdate("boot", "localmount");
await writeFstab(currRootPath);

// make VM disk image
const ext4Path = "raw.ext4";
await execFile("qemu-img", ["create", "-f", "raw", ext4Path, "50G"]);
await execFile("mkfs.ext4", [ext4Path]);

const mntdir = join(tmpdir(), "woodpecker-in-a-vm-" + nanoid());
await mkdir(mntdir);
await execFile("sudo", ["mount", ext4Path, mntdir]);
for (const path of await readdir(currRootPath))
  await execFile("sudo", ["cp", "-r", join(currRootPath, path), mntdir]);
await execFile("sudo", ["umount", mntdir]);
await execFile("sudo", [
  "qemu-img",
  "convert",
  "-O",
  "qcow2",
  ext4Path,
  "vm.qcow2",
]);

await copyFile(
  join(currRootPath, "boot/vmlinuz-virt"),
  "./vmlinuz-virt",
  constants.COPYFILE_FICLONE
);
await copyFile(
  join(currRootPath, "boot/initramfs-virt"),
  "./initramfs-virt",
  constants.COPYFILE_FICLONE
);
await execFile("sudo", [
  "chown",
  "1000:1000",
  "./vmlinuz-virt",
  "./initramfs-virt",
  "./vm.qcow2",
]);

async function setupRootfsDir() {
  const artifactsPath = "./artifacts";
  const currRootPath = join(artifactsPath, "rootfs" + nanoid());
  await mkdir(currRootPath, { recursive: true });

  {
    const currentPath = join(artifactsPath, "current");
    try {
      await rm(currentPath);
    } catch {}
    await symlink(basename(currRootPath), currentPath);
  }
  return "./" + currRootPath;
}

/**
 * @param {string} rootfs
 */
async function writeFstab(rootfs) {
  const rootfsName = "/dev/vda";
  const virtualDiskName = "/dev/vda";
  await writeFile(
    "fstab",
    `${rootfsName}	/	squashfs	rw,relatime,discard 0 1
`
  );
  await execFile("sudo", ["mv", "fstab", join(rootfs, "/etc/fstab")]);
}

/**
 * Corre comando en chroot
 * @param {string} rootfs
 * @param {string[]} cmd
 */
async function chroot(rootfs, cmd) {
  await execFile("sudo", ["chroot", rootfs, ...cmd]);
}

/**
 * @param {string} name
 * @returns {string} la variable conseguida
 */
function getConfig(name) {
  if (name in process.env) return process.env[name] || "";
  else throw new Error(`Falta la variable ${name}`);
}