gemini-cli/packages/cli/src/utils/sandbox.ts

/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import { execSync, spawnSync, spawn } from 'node:child_process';
import os from 'node:os';
import path from 'node:path';
import fs from 'node:fs';
import { quote } from 'shell-quote';
import {
  USER_SETTINGS_DIR,
  SETTINGS_DIRECTORY_NAME,
} from '../config/settings.js';

// node.js equivalent of scripts/sandbox_command.sh
export function sandbox_command(sandbox?: string | boolean): string {
  // note environment variable takes precedence over argument (from command line or settings)
  sandbox = process.env.GEMINI_CODE_SANDBOX?.toLowerCase().trim() ?? sandbox;
  if (sandbox === '1' || sandbox === 'true') sandbox = true;
  else if (sandbox === '0' || sandbox === 'false') sandbox = false;

  if (sandbox === true) {
    // look for docker or podman, in that order
    if (execSync('command -v docker || true').toString().trim()) {
      return 'docker'; // Set sandbox to 'docker' if found
    } else if (execSync('command -v podman || true').toString().trim()) {
      return 'podman'; // Set sandbox to 'podman' if found
    } else {
      console.error(
        'ERROR: failed to determine command for sandbox; ' +
          'install docker or podman or specify command in GEMINI_CODE_SANDBOX',
      );
      process.exit(1);
    }
  } else if (sandbox) {
    // confirm that specfied command exists
    if (execSync(`command -v ${sandbox} || true`).toString().trim()) {
      return sandbox;
    } else {
      console.error(
        `ERROR: missing sandbox command '${sandbox}' (from GEMINI_CODE_SANDBOX)`,
      );
      process.exit(1);
    }
  } else {
    return ''; // no sandbox
  }
}

// docker does not allow container names to contain ':' or '/', so we
// parse those out and make the name a little shorter
function parseImageName(image: string): string {
  const [fullName, tag] = image.split(':');
  const name = fullName.split('/').at(-1) ?? 'unknown-image';
  return tag ? `${name}-${tag}` : name;
}

function ports(): string[] {
  return (process.env.SANDBOX_PORTS ?? '')
    .split(',')
    .filter((p) => p.trim())
    .map((p) => p.trim());
}

function entrypoint(workdir: string): string[] {
  // set up bash command to be run inside container
  // start with setting up PATH and PYTHONPATH with optional suffixes from host
  const bashCmds = [];

  // copy any paths in PATH that are under working directory in sandbox
  // note we can't just pass these as --env since that would override base PATH
  // instead we construct a suffix and append as part of bashCmd below
  let pathSuffix = '';
  if (process.env.PATH) {
    const paths = process.env.PATH.split(':');
    for (const path of paths) {
      if (path.startsWith(workdir)) {
        pathSuffix += `:${path}`;
      }
    }
  }
  if (pathSuffix) {
    bashCmds.push(`export PATH="$PATH${pathSuffix}";`); // suffix includes leading ':'
  }

  // copy any paths in PYTHONPATH that are under working directory in sandbox
  // note we can't just pass these as --env since that would override base PYTHONPATH
  // instead we construct a suffix and append as part of bashCmd below
  let pythonPathSuffix = '';
  if (process.env.PYTHONPATH) {
    const paths = process.env.PYTHONPATH.split(':');
    for (const path of paths) {
      if (path.startsWith(workdir)) {
        pythonPathSuffix += `:${path}`;
      }
    }
  }
  if (pythonPathSuffix) {
    bashCmds.push(`export PYTHONPATH="$PYTHONPATH${pythonPathSuffix}";`); // suffix includes leading ':'
  }

  // source sandbox.bashrc if exists under project settings directory
  const projectSandboxBashrc = path.join(
    SETTINGS_DIRECTORY_NAME,
    'sandbox.bashrc',
  );
  if (fs.existsSync(projectSandboxBashrc)) {
    bashCmds.push(`source ${projectSandboxBashrc};`);
  }

  // also set up redirects (via socat) so servers can listen on localhost instead of 0.0.0.0
  ports().forEach((p) =>
    bashCmds.push(
      `socat TCP4-LISTEN:${p},bind=$(hostname -i),fork,reuseaddr TCP4:127.0.0.1:${p} 2> /dev/null &`,
    ),
  );

  // append remaining args (bash -c "gemini-code cli_args...")
  // cli_args need to be quoted before being inserted into bash_cmd
  const cliArgs = process.argv.slice(2).map((arg) => quote([arg]));
  const cliCmd =
    process.env.NODE_ENV === 'development'
      ? process.env.DEBUG
        ? 'npm run debug --'
        : 'npm run start --'
      : 'gemini-code';

  const args = [...bashCmds, cliCmd, ...cliArgs];

  return ['bash', '-c', args.join(' ')];
}

export async function start_sandbox(sandbox: string) {
  // determine full path for gemini-code to distinguish linked vs installed setting
  const gcPath = execSync(`realpath $(which gemini-code)`).toString().trim();

  const image = process.env.GEMINI_CODE_SANDBOX_IMAGE ?? 'gemini-code-sandbox';
  const workdir = process.cwd();

  // if BUILD_SANDBOX is set, then call scripts/build_sandbox.sh under gemini-code repo
  // note this can only be done with binary linked from gemini-code repo
  if (process.env.BUILD_SANDBOX) {
    if (!gcPath.includes('gemini-code/packages/')) {
      console.error(
        'ERROR: cannot BUILD_SANDBOX using installed gemini-code binary; ' +
          'run `npm link ./packages/cli` under gemini-code repo to switch to linked binary.',
      );
      process.exit(1);
    } else {
      console.log('building sandbox ...');
      const gcRoot = gcPath.split('/packages/')[0];
      // if project folder has sandbox.Dockerfile under project settings folder, use that
      let buildArgs = '';
      const projectSandboxDockerfile = path.join(
        SETTINGS_DIRECTORY_NAME,
        'sandbox.Dockerfile',
      );
      if (fs.existsSync(projectSandboxDockerfile)) {
        console.log(`using ${projectSandboxDockerfile} for sandbox`);
        buildArgs += `-f ${path.resolve(projectSandboxDockerfile)}`;
      }
      spawnSync(`cd ${gcRoot} && scripts/build_sandbox.sh ${buildArgs}`, {
        stdio: 'inherit',
        shell: true,
      });
    }
  }

  // stop if image is missing
  if (!execSync(`${sandbox} images -q ${image}`).toString().trim()) {
    const remedy = gcPath.includes('gemini-code/packages/')
      ? 'Try `scripts/build_sandbox.sh` under gemini-code repo.'
      : 'Please notify gemini-code-dev@google.com.';
    console.error(`ERROR: ${image} is missing. ${remedy}`);
    process.exit(1);
  }

  // use interactive tty mode and auto-remove container on exit
  // run init binary inside container to forward signals & reap zombies
  const args = ['run', '-it', '--rm', '--init', '--workdir', workdir];

  // mount current directory as working directory in sandbox (set via --workdir)
  args.push('--volume', `${process.cwd()}:${workdir}`);

  // mount user settings directory inside container, after creating if missing
  // note user/home changes inside sandbox and we mount at BOTH paths for consistency
  const userSettingsDirOnHost = USER_SETTINGS_DIR;
  const userSettingsDirInSandbox = `/home/node/${SETTINGS_DIRECTORY_NAME}`;
  if (!fs.existsSync(userSettingsDirOnHost)) {
    fs.mkdirSync(userSettingsDirOnHost);
  }
  args.push('--volume', `${userSettingsDirOnHost}:${userSettingsDirOnHost}`);
  if (userSettingsDirInSandbox !== userSettingsDirOnHost) {
    args.push(
      '--volume',
      `${userSettingsDirOnHost}:${userSettingsDirInSandbox}`,
    );
  }

  // mount os.tmpdir() as /tmp inside container
  args.push('--volume', `${os.tmpdir()}:/tmp`);

  // mount paths listed in SANDBOX_MOUNTS
  if (process.env.SANDBOX_MOUNTS) {
    for (let mount of process.env.SANDBOX_MOUNTS.split(',')) {
      if (mount.trim()) {
        // parse mount as from:to:opts
        let [from, to, opts] = mount.trim().split(':');
        to = to || from; // default to mount at same path inside container
        opts = opts || 'ro'; // default to read-only
        mount = `${from}:${to}:${opts}`;
        // check that from path is absolute
        if (!path.isAbsolute(from)) {
          console.error(
            `ERROR: path '${from}' listed in SANDBOX_MOUNTS must be absolute`,
          );
          process.exit(1);
        }
        // check that from path exists on host
        if (!fs.existsSync(from)) {
          console.error(
            `ERROR: missing mount path '${from}' listed in SANDBOX_MOUNTS`,
          );
          process.exit(1);
        }
        console.log(`SANDBOX_MOUNTS: ${from} -> ${to} (${opts})`);
        args.push('--volume', mount);
      }
    }
  }

  // expose env-specified ports on the sandbox
  ports().forEach((p) => args.push('--publish', `${p}:${p}`));

  if (process.env.DEBUG) {
    const debugPort = process.env.DEBUG_PORT || '9229';
    args.push(`--publish`, `${debugPort}:${debugPort}`);
  }

  // name container after image, plus numeric suffix to avoid conflicts
  const containerName = parseImageName(image);
  let index = 0;
  while (
    execSync(
      `${sandbox} ps -a --format "{{.Names}}" | grep "${containerName}-${index}" || true`,
    )
      .toString()
      .trim()
  ) {
    index++;
  }
  args.push(
    '--name',
    `${containerName}-${index}`,
    '--hostname',
    `${containerName}-${index}`,
  );

  // copy GEMINI_API_KEY
  if (process.env.GEMINI_API_KEY) {
    args.push('--env', `GEMINI_API_KEY=${process.env.GEMINI_API_KEY}`);
  }

  // copy GEMINI_CODE_MODEL
  if (process.env.GEMINI_CODE_MODEL) {
    args.push('--env', `GEMINI_CODE_MODEL=${process.env.GEMINI_CODE_MODEL}`);
  }

  // copy TERMINAL_TOOL to optionally enable shell tool
  if (process.env.TERMINAL_TOOL) {
    args.push('--env', `TERMINAL_TOOL=${process.env.TERMINAL_TOOL}`);
  }

  // copy TERM and COLORTERM to try to maintain terminal setup
  if (process.env.TERM) {
    args.push('--env', `TERM=${process.env.TERM}`);
  }
  if (process.env.COLORTERM) {
    args.push('--env', `COLORTERM=${process.env.COLORTERM}`);
  }

  // copy VIRTUAL_ENV if under working directory
  // also mount-replace VIRTUAL_ENV directory with <project_settings>/sandbox.venv
  // sandbox can then set up this new VIRTUAL_ENV directory using sandbox.bashrc (see below)
  // directory will be empty if not set up, which is still preferable to having host binaries
  if (process.env.VIRTUAL_ENV?.startsWith(workdir)) {
    const sandboxVenvPath = path.resolve(
      SETTINGS_DIRECTORY_NAME,
      'sandbox.venv',
    );
    if (!fs.existsSync(sandboxVenvPath)) {
      fs.mkdirSync(sandboxVenvPath, { recursive: true });
    }
    args.push('--volume', `${sandboxVenvPath}:${process.env.VIRTUAL_ENV}`);
    args.push('--env', `VIRTUAL_ENV=${process.env.VIRTUAL_ENV}`);
  }

  // copy additional environment variables from SANDBOX_ENV
  if (process.env.SANDBOX_ENV) {
    for (let env of process.env.SANDBOX_ENV.split(',')) {
      if ((env = env.trim())) {
        if (env.includes('=')) {
          console.log(`SANDBOX_ENV: ${env}`);
          args.push('--env', env);
        } else {
          console.error(
            'ERROR: SANDBOX_ENV must be a comma-separated list of key=value pairs',
          );
          process.exit(1);
        }
      }
    }
  }

  // set SANDBOX as container name
  args.push('--env', `SANDBOX=${containerName}-${index}`);

  // for podman only, use empty --authfile to skip unnecessary auth refresh overhead
  if (sandbox === 'podman') {
    const emptyAuthFilePath = path.join(os.tmpdir(), 'empty_auth.json');
    fs.writeFileSync(emptyAuthFilePath, '{}', 'utf-8');
    args.push('--authfile', emptyAuthFilePath);
  }

  // specify --user as "$(id -u):$(id -g)" if SANDBOX_SET_UID_GID is 1|true
  // only necessary if user mapping is not handled by sandboxing setup on host
  // (e.g. rootful docker on linux w/o userns-remap configured)
  if (['1', 'true'].includes(process.env.SANDBOX_SET_UID_GID ?? '')) {
    const uid = execSync('id -u').toString().trim();
    const gid = execSync('id -g').toString().trim();
    args.push('--user', `${uid}:${gid}`);
  }

  // push container image name
  args.push(image);

  // push container entrypoint (including args)
  args.push(...entrypoint(workdir));

  // spawn child and let it inherit stdio
  const child = spawn(sandbox, args, {
    stdio: 'inherit',
    detached: true,
  });

  // uncomment this line (and comment the await on following line) to let parent exit
  // child.unref();
  await new Promise((resolve) => {
    child.on('close', resolve);
  });
}