smartvm/ts/classes.imagemanager.ts

import * as plugins from './plugins.js';
import type { TFirecrackerArch } from './interfaces/index.js';
import { SmartVMError } from './interfaces/index.js';

/**
 * Helper to check if a file or directory exists.
 */
async function pathExists(filePath: string): Promise<boolean> {
  try {
    await plugins.fs.promises.access(filePath);
    return true;
  } catch {
    return false;
  }
}

/**
 * Manages Firecracker binaries, kernel images, and rootfs images.
 * Downloads and caches them in a local data directory.
 */
export class ImageManager {
  private dataDir: string;
  private arch: TFirecrackerArch;

  constructor(dataDir: string, arch: TFirecrackerArch = 'x86_64') {
    this.dataDir = dataDir;
    this.arch = arch;
  }

  /**
   * Ensure all required directories exist.
   */
  public async ensureDirectories(): Promise<void> {
    const dirs = [
      this.getBinDir(),
      this.getKernelsDir(),
      this.getRootfsDir(),
      this.getSocketsDir(),
    ];
    for (const dir of dirs) {
      await plugins.fs.promises.mkdir(dir, { recursive: true });
    }
  }

  /** Base directory for firecracker binaries. */
  public getBinDir(): string {
    return plugins.path.join(this.dataDir, 'bin');
  }

  /** Directory for kernel images. */
  public getKernelsDir(): string {
    return plugins.path.join(this.dataDir, 'kernels');
  }

  /** Directory for rootfs images. */
  public getRootfsDir(): string {
    return plugins.path.join(this.dataDir, 'rootfs');
  }

  /** Directory for Unix sockets. */
  public getSocketsDir(): string {
    return plugins.path.join(this.dataDir, 'sockets');
  }

  /**
   * Get the path to the firecracker binary for a given version.
   */
  public getFirecrackerPath(version: string): string {
    return plugins.path.join(this.getBinDir(), version, 'firecracker');
  }

  /**
   * Get the path to the jailer binary for a given version.
   */
  public getJailerPath(version: string): string {
    return plugins.path.join(this.getBinDir(), version, 'jailer');
  }

  /**
   * Check if a Firecracker binary for the given version exists.
   */
  public async hasBinary(version: string): Promise<boolean> {
    const binPath = this.getFirecrackerPath(version);
    return pathExists(binPath);
  }

  /**
   * Query the GitHub API for the latest Firecracker release version tag.
   */
  public async getLatestVersion(): Promise<string> {
    try {
      const response = await plugins.SmartRequest.create()
        .url('https://api.github.com/repos/firecracker-microvm/firecracker/releases/latest')
        .get();
      const data = await response.json() as { tag_name: string };
      return data.tag_name;
    } catch (err) {
      throw new SmartVMError(
        `Failed to fetch latest Firecracker version: ${(err as Error).message}`,
        'VERSION_FETCH_FAILED',
      );
    }
  }

  /**
   * Download and extract the Firecracker binary for a given version.
   */
  public async downloadFirecracker(version: string): Promise<string> {
    const targetDir = plugins.path.join(this.getBinDir(), version);
    await plugins.fs.promises.mkdir(targetDir, { recursive: true });

    // Firecracker release tarball naming:
    // firecracker-v1.5.0-x86_64.tgz containing release-v1.5.0-x86_64/firecracker-v1.5.0-x86_64
    const tag = version.startsWith('v') ? version : `v${version}`;
    const archiveName = `firecracker-${tag}-${this.arch}.tgz`;
    const downloadUrl = `https://github.com/firecracker-microvm/firecracker/releases/download/${tag}/${archiveName}`;

    const archivePath = plugins.path.join(targetDir, archiveName);

    try {
      // Download the archive
      const shell = new plugins.smartshell.Smartshell({ executor: 'bash' });
      await shell.exec(`curl -fSL -o "${archivePath}" "${downloadUrl}"`);

      // Extract the archive
      await shell.exec(`tar -xzf "${archivePath}" -C "${targetDir}"`);

      // Firecracker archives contain a directory like release-v1.5.0-x86_64/
      // with binaries named like firecracker-v1.5.0-x86_64
      const extractedDir = plugins.path.join(targetDir, `release-${tag}-${this.arch}`);
      const firecrackerSrc = plugins.path.join(extractedDir, `firecracker-${tag}-${this.arch}`);
      const jailerSrc = plugins.path.join(extractedDir, `jailer-${tag}-${this.arch}`);
      const firecrackerDst = this.getFirecrackerPath(version);
      const jailerDst = this.getJailerPath(version);

      // Move binaries to expected paths
      await shell.exec(`mv "${firecrackerSrc}" "${firecrackerDst}"`);
      if (await pathExists(jailerSrc)) {
        await shell.exec(`mv "${jailerSrc}" "${jailerDst}"`);
      }

      // Make executable
      await shell.exec(`chmod +x "${firecrackerDst}"`);

      // Clean up
      await shell.exec(`rm -rf "${archivePath}" "${extractedDir}"`);

      return firecrackerDst;
    } catch (err) {
      throw new SmartVMError(
        `Failed to download Firecracker ${version}: ${(err as Error).message}`,
        'DOWNLOAD_FAILED',
      );
    }
  }

  /**
   * Download a kernel image from a URL.
   */
  public async downloadKernel(url: string, name: string): Promise<string> {
    const kernelsDir = this.getKernelsDir();
    await plugins.fs.promises.mkdir(kernelsDir, { recursive: true });
    const kernelPath = plugins.path.join(kernelsDir, name);

    try {
      const shell = new plugins.smartshell.Smartshell({ executor: 'bash' });
      await shell.exec(`curl -fSL -o "${kernelPath}" "${url}"`);
      return kernelPath;
    } catch (err) {
      throw new SmartVMError(
        `Failed to download kernel from ${url}: ${(err as Error).message}`,
        'DOWNLOAD_FAILED',
      );
    }
  }

  /**
   * Download a rootfs image from a URL.
   */
  public async downloadRootfs(url: string, name: string): Promise<string> {
    const rootfsDir = this.getRootfsDir();
    await plugins.fs.promises.mkdir(rootfsDir, { recursive: true });
    const rootfsPath = plugins.path.join(rootfsDir, name);

    try {
      const shell = new plugins.smartshell.Smartshell({ executor: 'bash' });
      await shell.exec(`curl -fSL -o "${rootfsPath}" "${url}"`);
      return rootfsPath;
    } catch (err) {
      throw new SmartVMError(
        `Failed to download rootfs from ${url}: ${(err as Error).message}`,
        'DOWNLOAD_FAILED',
      );
    }
  }

  /**
   * Create a blank ext4 rootfs image.
   */
  public async createBlankRootfs(name: string, sizeMib: number): Promise<string> {
    const rootfsDir = this.getRootfsDir();
    await plugins.fs.promises.mkdir(rootfsDir, { recursive: true });
    const rootfsPath = plugins.path.join(rootfsDir, name);

    try {
      const shell = new plugins.smartshell.Smartshell({ executor: 'bash' });
      await shell.exec(`dd if=/dev/zero of="${rootfsPath}" bs=1M count=${sizeMib}`);
      await shell.exec(`mkfs.ext4 "${rootfsPath}"`);
      return rootfsPath;
    } catch (err) {
      throw new SmartVMError(
        `Failed to create blank rootfs: ${(err as Error).message}`,
        'ROOTFS_CREATE_FAILED',
      );
    }
  }

  /**
   * Clone a rootfs image for a specific VM.
   */
  public async cloneRootfs(sourcePath: string, targetName: string): Promise<string> {
    const rootfsDir = this.getRootfsDir();
    await plugins.fs.promises.mkdir(rootfsDir, { recursive: true });
    const targetPath = plugins.path.join(rootfsDir, targetName);

    try {
      const shell = new plugins.smartshell.Smartshell({ executor: 'bash' });
      await shell.exec(`cp "${sourcePath}" "${targetPath}"`);
      return targetPath;
    } catch (err) {
      throw new SmartVMError(
        `Failed to clone rootfs: ${(err as Error).message}`,
        'ROOTFS_CLONE_FAILED',
      );
    }
  }

  /**
   * Generate a unique socket path for a VM.
   */
  public getSocketPath(vmId: string): string {
    return plugins.path.join(this.getSocketsDir(), `${vmId}.sock`);
  }
}