byrd/baker.py

from getpass import getpass
from hashlib import md5
from itertools import chain
from collections import ChainMap, OrderedDict, defaultdict
import argparse
import io
import logging
import os
import posixpath
import subprocess
import sys
import threading

import paramiko
import yaml


try:
    import keyring
except ImportError:
    keyring = None

__version__ = '0.0'


log_fmt = '%(levelname)s:%(asctime).19s: %(message)s'
logger = logging.getLogger('baker')
logger.setLevel(logging.INFO)
log_handler = logging.StreamHandler()
log_handler.setLevel(logging.INFO)
log_handler.setFormatter(logging.Formatter(log_fmt))
logger.addHandler(log_handler)


TAB = '\n    '

class BakerException(Exception):
    pass

class FmtException(BakerException):
    pass

class ExecutionException(BakerException):
    pass

class RemoteException(ExecutionException):
    pass

class LocalException(ExecutionException):
    pass

def enable_logging_color():
    try:
        import colorama
    except ImportError:
        return

    colorama.init()
    MAGENTA = colorama.Fore.MAGENTA
    RED = colorama.Fore.RED
    RESET = colorama.Style.RESET_ALL

    # We define custom handler ..
    class Handler(logging.StreamHandler):
        def format(self, record):
            if record.levelname == 'INFO':
                record.msg = MAGENTA + record.msg + RESET
            elif record.levelname in ('WARNING', 'ERROR', 'CRITICAL'):
                record.msg = RED + record.msg + RESET
            return super(Handler, self).format(record)

    #  .. and plug it
    logger.removeHandler(log_handler)
    handler = Handler()
    handler.setFormatter(logging.Formatter(log_fmt))
    logger.addHandler(handler)
    logger.propagate = 0


def yaml_load(stream):
    class OrderedLoader(yaml.Loader):
        pass

    def construct_mapping(loader, node):
        loader.flatten_mapping(node)
        return OrderedDict(loader.construct_pairs(node))
    OrderedLoader.add_constructor(
        yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG,
        construct_mapping)
    return yaml.load(stream, OrderedLoader)


def edits(word):
    yield word
    splits = ((word[:i], word[i:]) for i in range(len(word) + 1))
    for left, right in splits:
        if right:
            yield left + right[1:]


def gen_candidates(wordlist):
    candidates = defaultdict(set)
    for word in wordlist:
        for ed1 in edits(word):
            for ed2 in edits(ed1):
                candidates[ed2].add(word)
    return candidates


def spell(candidates,  word):
    matches = set(chain.from_iterable(
        candidates[ed] for ed in edits(word) if ed in candidates
    ))
    return matches


def spellcheck(objdict, word):
    if word in objdict:
        return

    candidates = objdict.get('_candidates')
    if not candidates:
        candidates = gen_candidates(list(objdict))
        objdict._candidates = candidates

    msg = '"%s" not found in %s' % (word, objdict._path)
    matches = spell(candidates, word)
    if matches:
        msg += ', try: %s' % ' or '.join(matches)
    raise BakerException(msg)


class ObjectDict(dict):
    """
    Simple objet sub-class that allows to transform a dict into an
    object, like: `ObjectDict({'ham': 'spam'}).ham == 'spam'`
    """
    _meta = {}

    def __getattr__(self, key):
        if key.startswith('_'):
            return ObjectDict._meta[id(self), key]

        if key in self:
            return self[key]
        else:
            return None

    def __setattr__(self, key, value):
        if key.startswith('_'):
            ObjectDict._meta[id(self), key] = value
        else:
            self[key] = value

class Node:

    @staticmethod
    def fail(path, kind):
        msg = 'Error while parsing config: expecting "%s" while parsing "%s"'
        raise BakerException(msg % (kind, '->'.join(path)))

    @classmethod
    def parse(cls, cfg, path=tuple()):
        children = getattr(cls, '_children', None)
        type_name = children and type(children).__name__ \
                    or ' or '.join((c.__name__ for c in cls._type))
        res = None
        if type_name == 'dict':
            if not isinstance(cfg, dict):
                cls.fail(path, type_name)
            res = ObjectDict()

            if '*' in children:
                assert len(children) == 1, "Don't mix '*' and other keys"
                child_class = children['*']
                for name, value in cfg.items():
                    res[name] = child_class.parse(value, path + (name,))
            else:
                # Enforce known pre-defined
                for key in cfg:
                    if key not in children:
                        path = ' -> '.join(path)
                        if path:
                            msg = 'Attribute "%s" not understood in %s' % (
                                key, path)
                        else:
                            msg = 'Top-level attribute "%s" not understood' % (
                                key)
                        candidates = gen_candidates(children.keys())
                        matches = spell(candidates, key)
                        if matches:
                            msg += ', try: %s' % ' or '.join(matches)
                        raise BakerException(msg)

                for name, child_class in children.items():
                    if name not in cfg:
                        continue
                    res[name] = child_class.parse(cfg.pop(name), path + (name,))

        elif type_name == 'list':
            if not isinstance(cfg, list):
                cls.fail(path, type_name)
            child_class = children[0]
            res = [child_class.parse(c, path+ ('[]',)) for c in cfg]

        else:
            if not isinstance(cfg, cls._type):
                cls.fail(path, type_name)
            res = cfg

        return cls.setup(res, path)

    @classmethod
    def setup(cls, values, path):
        if isinstance(values, ObjectDict):
            values._path = '->'.join(path)
        return values


class Atom(Node):
    _type = (str, bool)

class AtomList(Node):
    _children = [Atom]

class Hosts(Node):
    _children = [Atom]

class Auth(Node):
    _children = {'*': Atom}

class EnvNode(Node):
    _children = {'*': Atom}

class HostGroup(Node):
    _children = {
        'hosts': Hosts,
    }

class Network(Node):
    _children = {
        '*': HostGroup,
    }

class Multi(Node):
    _children = {
        'task': Atom,
        'export': Atom,
        'network': Atom,
    }

class MultiList(Node):
    _children = [Multi]

class Task(Node):
    _children = {
        'desc': Atom,
        'local': Atom,
        'python': Atom,
        'once': Atom,
        'run': Atom,
        'sudo': Atom,
        'send': Atom,
        'to': Atom,
        'assert': Atom,
        'env': EnvNode,
        'multi': MultiList,
    }

    @classmethod
    def setup(cls, values, path):
        values['name'] = path and path[-1] or ''
        if 'desc' not in values:
            values['desc'] = values.get('name', '')
        super().setup(values, path)
        return values


class TaskGroup(Node):
    _children = {
        '*': Task,
    }

class LoadNode(Node):
    _children = {
        'file': Atom,
        'as': Atom,
    }

class LoadList(Node):
    _children = [LoadNode]

class ConfigRoot(Node):
    _children = {
        'networks': Network,
        'tasks': TaskGroup,
        'auth': Auth,
        'env': EnvNode,
        'load': LoadList,
    }

# Multi can also accept any task attribute:
Multi._children.update(Task._children)



class Env(ChainMap):

    def __init__(self, *dicts):
        return super().__init__(*filter(lambda x: x is not None, dicts))

    def fmt(self, string):
        try:
            return string.format(**self)
        except KeyError as exc:
            msg = 'Unable to format "%s" (missing: "%s")'% (string, exc.args[0])
            candidates = gen_candidates(self.keys())
            key = exc.args[0]
            matches = spell(candidates, key)
            if matches:
                msg += ', try: %s' % ' or '.join(matches)
            raise FmtException(msg )
        except IndexError as exc:
            msg = 'Unable to format "%s", positional argument not supported'
            raise FmtException(msg)


def get_passphrase(key_path):
    service = 'SSH private key'
    csum = md5(open(key_path, 'rb').read()).digest().hex()
    ssh_pass = keyring.get_password(service, csum)
    if not ssh_pass:
        ssh_pass = getpass('Password for %s: ' % key_path)
        keyring.set_password(service, csum, ssh_pass)
    return ssh_pass


def get_password(host):
    service = 'SSH password'
    ssh_pass = keyring.get_password(service, host)
    if not ssh_pass:
        ssh_pass = getpass('Password for %s: ' % host)
        keyring.set_password(service, host, ssh_pass)
    return ssh_pass


def get_sudo_passwd():
    service = "Sudo password"
    passwd = keyring.get_password(service, '-')
    if not passwd:
        passwd = getpass('Sudo password:')
        keyring.set_password(service, '-', passwd)
    return passwd


CONNECTION_CACHE = {}
def connect(host, auth):
    if host in CONNECTION_CACHE:
        return CONNECTION_CACHE[host]

    private_key_file = password = None
    if auth and auth.get('ssh_private_key'):
        private_key_file = auth.ssh_private_key
        if not os.path.exists(auth.ssh_private_key):
            msg = 'Private key file "%s" not found' % auth.ssh_private_key
            raise BakerException(msg)
        password = get_passphrase(auth.ssh_private_key)
    else:
        password = get_password(host)

    username, hostname = host.split('@', 1)

    client = paramiko.SSHClient()
    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    client.connect(hostname, username=username, password=password,
                   key_filename=private_key_file,
    )
    CONNECTION_CACHE[host] = client
    return client


def run_local(cmd, env, cli):
    # Run local task
    cmd = env.fmt(cmd)
    logger.info(env.fmt('{task_desc}'))
    if cli.dry_run:
        logger.info('[dry-run] ' + cmd)
        return None
    logger.debug(TAB + TAB.join(cmd.splitlines()))
    process = subprocess.Popen(
        cmd, shell=True,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        env=env,
    )
    stdout, stderr = process.communicate()
    success = process.returncode == 0
    if stdout:
        logger.debug(TAB + TAB.join(stdout.decode().splitlines()))
    if not success:
        raise LocalException(stdout, stderr)
    return ObjectDict(stdout=stdout, stderr=stderr)


def run_python(task, env, cli):
    # Execute a piece of python localy
    code = task.python
    logger.info(env.fmt('{task_desc}'))
    if cli.dry_run:
        logger.info('[dry-run] ' + code)
        return None
    logger.debug(TAB + TAB.join(code.splitlines()))
    cmd = 'python -c "import sys;exec(sys.stdin.read())"'
    if task.sudo:
        cmd = 'sudo -- ' + cmd
    process = subprocess.Popen(
        cmd,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        stdin=subprocess.PIPE,
        env=env,
    )

    # Plug io
    out_buff = io.StringIO()
    err_buff = io.StringIO()
    log_stream(process.stdout, out_buff)
    log_stream(process.stderr, err_buff)
    process.stdin.write(code.encode())
    process.stdin.flush()
    process.stdin.close()
    success = process.wait() == 0
    process.stdout.close()
    process.stderr.close()
    out = out_buff.getvalue()
    if out:
        logger.debug(TAB + TAB.join(out.splitlines()))
    if not success:
        raise LocalException(out + err_buff.getvalue())
    return ObjectDict(stdout=out, stderr=err_buff.getvalue())


def log_stream(stream, buff):
    def _log():
        try:
            for chunk in iter(lambda: stream.readline(2048), ""):
                if isinstance(chunk, bytes):
                    chunk = chunk.decode()
                buff.write(chunk)
        except ValueError:
            # read raises a ValueError on closed stream
            pass

    t = threading.Thread(target=_log)
    t.start()
    return t


def run_helper(client, cmd, env=None, in_buff=None, sudo=False):
    chan = client.get_transport().open_session()
    if env:
        chan.update_environment(env)

    stdin = chan.makefile('wb')
    stdout = chan.makefile('r')
    stderr = chan.makefile_stderr('r')
    out_buff = io.StringIO()
    err_buff = io.StringIO()
    out_thread = log_stream(stdout, out_buff)
    err_thread = log_stream(stderr, err_buff)

    if sudo:
        assert not in_buff, 'in_buff and sudo can not be combined'
        if isinstance(sudo, str):
            sudo_cmd = 'sudo -u %s -s' % sudo
        else:
            sudo_cmd = 'sudo -s'
        chan.exec_command(sudo_cmd)
        in_buff = cmd
    else:
        chan.exec_command(cmd)
    if in_buff:
        # XXX use a real buff (not a simple str) ?
        stdin.write(in_buff)
        stdin.flush()
        stdin.close()
        chan.shutdown_write()

    success = chan.recv_exit_status() == 0
    out_thread.join()
    err_thread.join()

    if not success:
        raise RemoteException(out_buff.getvalue() + err_buff.getvalue())

    res = ObjectDict(
        stdout = out_buff.getvalue(),
        stderr = err_buff.getvalue(),
    )
    return res


def run_remote(task, host, env, cli):
    res = None
    host = env.fmt(host)
    env.update({
        'host': host,
    })
    if cli.dry_run:
        client = None
    else:
        client = connect(host, cli.cfg.auth)
    if task.run:
        cmd = env.fmt(task.run)
        prefix = ''
        if task.sudo:
            if task.sudo is True:
                prefix = '[sudo] '
            else:
                 prefix = '[sudo as %s] ' % task.sudo
        msg = prefix + '{host}: {task_desc}'
        logger.info(env.fmt(msg))
        logger.debug(TAB + TAB.join(cmd.splitlines()))
        if cli.dry_run:
            logger.info('[dry-run] ' + cmd)
        else:
            res = run_helper(client, cmd, env=env, sudo=task.sudo)

    elif task.send:
        local_path = env.fmt(task.send)
        remote_path = env.fmt(task.to)
        logger.info(f'[send] {local_path} -> {host}:{remote_path}')
        if cli.dry_run:
            logger.info('[dry-run]')
            return
        else:
            with client.open_sftp() as sftp:
                if os.path.isfile(local_path):
                    sftp.put(os.path.abspath(local_path), remote_path)
                else:
                    for root, subdirs, files in os.walk(local_path):
                        rel_dir = os.path.relpath(root, local_path)
                        rem_dir = posixpath.join(remote_path, rel_dir)
                        run_helper(client, 'mkdir -p {}'.format(rem_dir))
                        for f in files:
                            rel_f = os.path.join(root, f)
                            rem_file = posixpath.join(rem_dir, f)
                            sftp.put(os.path.abspath(rel_f), rem_file)
    else:
        raise BakerException('Unable to run task "%s"' % task.name)

    if res and res.stdout:
        logger.debug(TAB + TAB.join(res.stdout.splitlines()))

    return res


def run_task(task, host, cli, parent_env=None):
    '''
    Execute one task on one host (or locally)
    '''

    # Prepare environment
    env = Env(
        # Env from parent task
        parent_env,
        # Env on the task itself
        task.get('env'),
        # Top-level env
        cli.cfg.get('env'),
        # OS env
        os.environ,
    ).new_child()

    env.update({
        'task_desc': env.fmt(task.desc),
        'task_name': task.name,
        'host': host or '',
    })

    if task.local:
        res = run_local(task.local, env, cli)
    elif task.python:
        res = run_python(task, env, cli)
    else:
        res = run_remote(task, host, env, cli)

    if task.get('assert'):
        env.update({
            'stdout': res.stdout.strip(),
            'stderr': res.stderr.strip(),
        })
        assert_ = env.fmt(task['assert'])
        ok = eval(assert_, dict(env))
        if ok:
            logger.info('Assert ok')
        else:
            raise BakerException('Assert "%s" failed!' % assert_)
    return res


def run_batch(task, hosts, cli, env=None):
    '''
    Run one task on a list of hosts
    '''
    out = None
    export_env = {}
    env = Env(export_env, task.get('env'), env)

    if task.get('multi'):
        parent_sudo = task.sudo
        for multi in task.multi:
            task_name = multi.task
            if task:
                # _cfg contain "local" config wrt the task
                siblings = task._cfg.tasks
                spellcheck(siblings, task_name)
                sub_task = siblings[task_name]
                sudo = multi.sudo or sub_task.sudo or parent_sudo
            else:
                # reify a task out of attributes
                sub_task = Task.parse(multi)
                sudo = sub_task.sudo or parent_sudo
            sub_task.sudo = sudo
            network = multi.get('network')
            if network:
                spellcheck(cli.cfg.networks, network)
                hosts = cli.cfg.networks[network].hosts
            child_env = Env(multi.get('env', {}), env)
            for k, v in child_env.items():
                # env wrap-around!
                child_env[k] = child_env.fmt(child_env[k])
            out = run_batch(sub_task, hosts, cli, child_env)
            out = out.decode() if isinstance(out, bytes) else out
            export_env['_'] = out
            if multi.export:
                export_env[multi.export] = out

    else:
        res = None
        if task.once and (task.local or task.python):
            res = run_task(task, None, cli, env)
        else:
            for host in hosts:
                res = run_task(task, host, cli, env)
                if task.once:
                    break
        out = res and res.stdout.strip() or ''
    return out


def abort(msg):
    logger.error(msg)
    sys.exit(1)


def load_cfg(path, prefix=None):
    load_sections = ('networks', 'tasks', 'auth', 'env')

    if os.path.isfile(path):
        logger.info('Load config %s' % path)
        cfg = yaml_load(open(path))
        cfg = ConfigRoot.parse(cfg)
    else:
        raise BakerException('Config file "%s" not found' % path)

    # Define useful defaults
    cfg.networks = cfg.networks or ObjectDict()
    cfg.tasks = cfg.tasks or ObjectDict()

    # Create backrefs between tasks to the local config
    if cfg.get('tasks'):
        items = cfg['tasks'].items()
        for k, v in items:
            v._cfg = ObjectDict(cfg.copy())

    if prefix:
        key_fn = lambda x: '/'.join(prefix + [x])
        # Apply prefix
        for section in load_sections:
            if not cfg.get(section):
                continue
            items = cfg[section].items()
            cfg[section] = {key_fn(k): v for k, v in items}

    # Recursive load
    if cfg.load:
        cfg_path = os.path.dirname(path)
        for item in cfg.load:
            if item.get('as'):
                child_prefix = item['as']
            else:
                child_prefix, _ = os.path.splitext(item.file)
            child_path = os.path.join(cfg_path, item.file)
            child_cfg = load_cfg(child_path, child_prefix.split('/'))

            for section in load_sections:
                cfg[section].update(child_cfg.get(section, {}))
    return cfg


def load_cli(args=None):
    parser = argparse.ArgumentParser()
    parser.add_argument('names',  nargs='*',
                        help='Hosts and commands to run them on')
    parser.add_argument('-c', '--config', default='bk.yaml',
                        help='Config file')
    parser.add_argument('-R', '--run', nargs='*', default=[],
                        help='Run remote task')
    parser.add_argument('-L', '--run-local', nargs='*', default=[],
                        help='Run local task')
    parser.add_argument('-P', '--run-python', nargs='*', default=[],
                        help='Run python task')
    parser.add_argument('-d', '--dry-run', action='store_true',
                        help='Do not run actual tasks, just print them')
    parser.add_argument('-e', '--env', nargs='*', default=[],
                        help='Add value to execution environment '
                        '(ex: -e foo=bar "name=John Doe")')
    parser.add_argument('-s', '--sudo', default='auto',
                        help='Enable sudo (auto|yes|no')
    parser.add_argument('-v', '--verbose', action='count',
                        default=0, help='Increase verbosity')
    parser.add_argument('-q', '--quiet', action='count',
                        default=0, help='Decrease verbosity')
    parser.add_argument('-n', '--no-color', action='store_true',
                        help='Disable colored logs')
    cli = parser.parse_args(args=args)
    cli = ObjectDict(vars(cli))

    # Load config
    cfg = load_cfg(cli.config)
    cli.cfg = cfg
    cli.update(get_hosts_and_tasks(cli, cfg))

    # Transformt env string into dict
    cli.env = dict(e.split('=') for e in cli.env)
    return cli

def get_hosts_and_tasks(cli, cfg):
    # Make sure we don't have overlap between hosts and tasks
    items = list(cfg.networks) + list(cfg.tasks)
    msg = 'Name collision between tasks and networks'
    assert len(set(items)) == len(items), msg

    # Build task list
    tasks = []
    networks = []
    for name in cli.names:
        if name in cfg.networks:
            host = cfg.networks[name]
            networks.append(host)
        elif name in cfg.tasks:
            task = cfg.tasks[name]
            tasks.append(task)
        else:
            msg = 'Name "%s" not understood' % name
            matches = spell(cfg.networks, name) | spell(cfg.tasks, name)
            if matches:
                msg += ', try: %s' % ' or '.join(matches)
            raise BakerException (msg)

    # Collect custom tasks from cli
    customs = []
    for cli_key in ('run', 'run_local', 'run_python'):
        cmd_key = cli_key.rsplit('_', 1)[-1]
        customs.extend('%s: %s' % (cmd_key, ck) for ck in cli[cli_key])
    for custom_task in customs:
        task = Task.parse(yaml_load(custom_task))
        task.desc = 'Custom command'
        tasks.append(task)

    hosts = list(chain.from_iterable(n.hosts for n in networks))

    return dict(hosts=hosts, tasks=tasks)


def main():
    cli = None
    try:
        cli = load_cli()
        if not cli.no_color:
            enable_logging_color()
        cli.verbose = max(0, 1 + cli.verbose - cli.quiet)
        level = ['WARNING', 'INFO', 'DEBUG'][min(cli.verbose, 2)]
        log_handler.setLevel(level)
        logger.setLevel(level)

        for task in cli.tasks:
            run_batch(task, cli.hosts, cli, cli.env)
    except BakerException as e:
        if cli and cli.verbose > 2:
            raise
        abort(str(e))


if __name__ == '__main__':
    main()