~oddbloke/cloud-init/lp1506187

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# vi: ts=4 expandtab
#
#    Copyright (C) 2013 Canonical Ltd.
#
#    Author: Scott Moser <scott.moser@canonical.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License version 3, as
#    published by the Free Software Foundation.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

import base64
import contextlib
import crypt
import fnmatch
import os
import os.path
import time
import xml.etree.ElementTree as ET

from xml.dom import minidom

from cloudinit import log as logging
from cloudinit.settings import PER_ALWAYS
from cloudinit import sources
from cloudinit import util
from cloudinit.sources.helpers.azure import (
    get_metadata_from_fabric, iid_from_shared_config_content)

LOG = logging.getLogger(__name__)

DS_NAME = 'Azure'
DEFAULT_METADATA = {"instance-id": "iid-AZURE-NODE"}
AGENT_START = ['service', 'walinuxagent', 'start']
BOUNCE_COMMAND = ['sh', '-xc',
    "i=$interface; x=0; ifdown $i || x=$?; ifup $i || x=$?; exit $x"]
DATA_DIR_CLEAN_LIST = ['SharedConfig.xml']

BUILTIN_DS_CONFIG = {
    'agent_command': AGENT_START,
    'data_dir': "/var/lib/waagent",
    'set_hostname': True,
    'hostname_bounce': {
        'interface': 'eth0',
        'policy': True,
        'command': BOUNCE_COMMAND,
        'hostname_command': 'hostname',
        },
    'disk_aliases': {'ephemeral0': '/dev/sdb'},
}

BUILTIN_CLOUD_CONFIG = {
    'disk_setup': {
        'ephemeral0': {'table_type': 'gpt',
                       'layout': [100],
                       'overwrite': True},
        },
    'fs_setup': [{'filesystem': 'ext4',
                  'device': 'ephemeral0.1',
                  'replace_fs': 'ntfs'}],
}

DS_CFG_PATH = ['datasource', DS_NAME]
DEF_EPHEMERAL_LABEL = 'Temporary Storage'

# The redacted password fails to meet password complexity requirements
# so we can safely use this to mask/redact the password in the ovf-env.xml
DEF_PASSWD_REDACTION = 'REDACTED'


def get_hostname(hostname_command='hostname'):
    return util.subp(hostname_command, capture=True)[0].strip()


def set_hostname(hostname, hostname_command='hostname'):
    util.subp([hostname_command, hostname])


@contextlib.contextmanager
def temporary_hostname(temp_hostname, cfg, hostname_command='hostname'):
    """
    Set a temporary hostname, restoring the previous hostname on exit.

    Will have the value of the previous hostname when used as a context
    manager, or None if the hostname was not changed.
    """
    policy = cfg['hostname_bounce']['policy']
    previous_hostname = get_hostname(hostname_command)
    if (not util.is_true(cfg.get('set_hostname'))
            or util.is_false(policy)
            or (previous_hostname == temp_hostname and policy != 'force')):
        yield None
        return
    set_hostname(temp_hostname, hostname_command)
    try:
        yield previous_hostname
    finally:
        set_hostname(previous_hostname, hostname_command)


class DataSourceAzureNet(sources.DataSource):
    def __init__(self, sys_cfg, distro, paths):
        sources.DataSource.__init__(self, sys_cfg, distro, paths)
        self.seed_dir = os.path.join(paths.seed_dir, 'azure')
        self.cfg = {}
        self.seed = None
        self.ds_cfg = util.mergemanydict([
            util.get_cfg_by_path(sys_cfg, DS_CFG_PATH, {}),
            BUILTIN_DS_CONFIG])

    def __str__(self):
        root = sources.DataSource.__str__(self)
        return "%s [seed=%s]" % (root, self.seed)

    def get_metadata_from_agent(self):
        temp_hostname = self.metadata.get('local-hostname')
        hostname_command = self.ds_cfg['hostname_bounce']['hostname_command']
        with temporary_hostname(temp_hostname, self.ds_cfg,
                                hostname_command=hostname_command) \
                as previous_hostname:
            if (previous_hostname is not None
                    and util.is_true(self.ds_cfg.get('set_hostname'))):
                cfg = self.ds_cfg['hostname_bounce']
                try:
                    perform_hostname_bounce(hostname=temp_hostname,
                                            cfg=cfg,
                                            prev_hostname=previous_hostname)
                except Exception as e:
                    LOG.warn("Failed publishing hostname: %s", e)
                    util.logexc(LOG, "handling set_hostname failed")

            try:
                invoke_agent(self.ds_cfg['agent_command'])
            except util.ProcessExecutionError:
                # claim the datasource even if the command failed
                util.logexc(LOG, "agent command '%s' failed.",
                            self.ds_cfg['agent_command'])

            ddir = self.ds_cfg['data_dir']
            shcfgxml = os.path.join(ddir, "SharedConfig.xml")
            wait_for = [shcfgxml]

            fp_files = []
            key_value = None
            for pk in self.cfg.get('_pubkeys', []):
                if pk.get('value', None):
                    key_value = pk['value']
                    LOG.debug("ssh authentication: using value from fabric")
                else:
                    bname = str(pk['fingerprint'] + ".crt")
                    fp_files += [os.path.join(ddir, bname)]
                    LOG.debug("ssh authentication: using fingerprint from fabirc")

            missing = util.log_time(logfunc=LOG.debug, msg="waiting for files",
                                    func=wait_for_files,
                                    args=(wait_for + fp_files,))
        if len(missing):
            LOG.warn("Did not find files, but going on: %s", missing)

        metadata = {}
        if shcfgxml in missing:
            LOG.warn("SharedConfig.xml missing, using static instance-id")
        else:
            try:
                metadata['instance-id'] = iid_from_shared_config(shcfgxml)
            except ValueError as e:
                LOG.warn("failed to get instance id in %s: %s", shcfgxml, e)

        metadata['public-keys'] = key_value or pubkeys_from_crt_files(fp_files)
        return metadata

    def get_data(self):
        # azure removes/ejects the cdrom containing the ovf-env.xml
        # file on reboot.  So, in order to successfully reboot we
        # need to look in the datadir and consider that valid
        ddir = self.ds_cfg['data_dir']

        candidates = [self.seed_dir]
        candidates.extend(list_possible_azure_ds_devs())
        if ddir:
            candidates.append(ddir)

        found = None

        for cdev in candidates:
            try:
                if cdev.startswith("/dev/"):
                    ret = util.mount_cb(cdev, load_azure_ds_dir)
                else:
                    ret = load_azure_ds_dir(cdev)

            except NonAzureDataSource:
                continue
            except BrokenAzureDataSource as exc:
                raise exc
            except util.MountFailedError:
                LOG.warn("%s was not mountable", cdev)
                continue

            (md, self.userdata_raw, cfg, files) = ret
            self.seed = cdev
            self.metadata = util.mergemanydict([md, DEFAULT_METADATA])
            self.cfg = util.mergemanydict([cfg, BUILTIN_CLOUD_CONFIG])
            found = cdev

            LOG.debug("found datasource in %s", cdev)
            break

        if not found:
            return False

        if found == ddir:
            LOG.debug("using files cached in %s", ddir)

        # azure / hyper-v provides random data here
        seed = util.load_file("/sys/firmware/acpi/tables/OEM0",
                              quiet=True, decode=False)
        if seed:
            self.metadata['random_seed'] = seed

        # now update ds_cfg to reflect contents pass in config
        user_ds_cfg = util.get_cfg_by_path(self.cfg, DS_CFG_PATH, {})
        self.ds_cfg = util.mergemanydict([user_ds_cfg, self.ds_cfg])

        if found != ddir:
            cached_ovfenv = util.load_file(
                os.path.join(ddir, 'ovf-env.xml'), quiet=True, decode=False)
            if cached_ovfenv != files['ovf-env.xml']:
                # source was not walinux-agent's datadir, so we have to clean
                # up so 'wait_for_files' doesn't return early due to stale data
                cleaned = []
                for f in [os.path.join(ddir, f) for f in DATA_DIR_CLEAN_LIST]:
                    if os.path.exists(f):
                        util.del_file(f)
                        cleaned.append(f)
                if cleaned:
                    LOG.info("removed stale file(s) in '%s': %s",
                             ddir, str(cleaned))

        # walinux agent writes files world readable, but expects
        # the directory to be protected.
        write_files(ddir, files, dirmode=0o700)

        if self.ds_cfg['agent_command'] == '__builtin__':
            metadata_func = get_metadata_from_fabric
        else:
            metadata_func = self.get_metadata_from_agent
        try:
            fabric_data = metadata_func()
        except Exception as exc:
            LOG.info("Error communicating with Azure fabric; assume we aren't"
                     " on Azure.", exc_info=True)
            return False

        self.metadata.update(fabric_data)

        found_ephemeral = find_fabric_formatted_ephemeral_disk()
        if found_ephemeral:
            self.ds_cfg['disk_aliases']['ephemeral0'] = found_ephemeral
            LOG.debug("using detected ephemeral0 of %s", found_ephemeral)

        cc_modules_override = support_new_ephemeral(self.sys_cfg)
        if cc_modules_override:
            self.cfg['cloud_config_modules'] = cc_modules_override

        return True

    def device_name_to_device(self, name):
        return self.ds_cfg['disk_aliases'].get(name)

    def get_config_obj(self):
        return self.cfg


def count_files(mp):
    return len(fnmatch.filter(os.listdir(mp), '*[!cdrom]*'))


def find_fabric_formatted_ephemeral_part():
    """
    Locate the first fabric formatted ephemeral device.
    """
    potential_locations = ['/dev/disk/cloud/azure_resource-part1',
                           '/dev/disk/azure/resource-part1']
    device_location = None
    for potential_location in potential_locations:
        if os.path.exists(potential_location):
            device_location = potential_location
            break
    if device_location is None:
        return None
    ntfs_devices = util.find_devs_with("TYPE=ntfs")
    real_device = os.path.realpath(device_location)
    if real_device in ntfs_devices:
        return device_location
    return None


def find_fabric_formatted_ephemeral_disk():
    """
    Get the ephemeral disk.
    """
    part_dev = find_fabric_formatted_ephemeral_part()
    if part_dev:
        return part_dev.split('-')[0]
    return None


def support_new_ephemeral(cfg):
    """
    Windows Azure makes ephemeral devices ephemeral to boot; a ephemeral device
    may be presented as a fresh device, or not.

    Since the knowledge of when a disk is supposed to be plowed under is
    specific to Windows Azure, the logic resides here in the datasource. When a
    new ephemeral device is detected, cloud-init overrides the default
    frequency for both disk-setup and mounts for the current boot only.
    """
    device = find_fabric_formatted_ephemeral_part()
    if not device:
        LOG.debug("no default fabric formated ephemeral0.1 found")
        return None
    LOG.debug("fabric formated ephemeral0.1 device at %s", device)

    file_count = 0
    try:
        file_count = util.mount_cb(device, count_files)
    except:
        return None
    LOG.debug("fabric prepared ephmeral0.1 has %s files on it", file_count)

    if file_count >= 1:
        LOG.debug("fabric prepared ephemeral0.1 will be preserved")
        return None
    else:
        # if device was already mounted, then we need to unmount it
        # race conditions could allow for a check-then-unmount
        # to have a false positive. so just unmount and then check.
        try:
            util.subp(['umount', device])
        except util.ProcessExecutionError as e:
            if device in util.mounts():
                LOG.warn("Failed to unmount %s, will not reformat.", device)
                LOG.debug("Failed umount: %s", e)
                return None

    LOG.debug("cloud-init will format ephemeral0.1 this boot.")
    LOG.debug("setting disk_setup and mounts modules 'always' for this boot")

    cc_modules = cfg.get('cloud_config_modules')
    if not cc_modules:
        return None

    mod_list = []
    for mod in cc_modules:
        if mod in ("disk_setup", "mounts"):
            mod_list.append([mod, PER_ALWAYS])
            LOG.debug("set module '%s' to 'always' for this boot", mod)
        else:
            mod_list.append(mod)
    return mod_list


def perform_hostname_bounce(hostname, cfg, prev_hostname):
    # set the hostname to 'hostname' if it is not already set to that.
    # then, if policy is not off, bounce the interface using command
    command = cfg['command']
    interface = cfg['interface']
    policy = cfg['policy']

    msg = ("hostname=%s policy=%s interface=%s" %
           (hostname, policy, interface))
    env = os.environ.copy()
    env['interface'] = interface
    env['hostname'] = hostname
    env['old_hostname'] = prev_hostname

    if command == "builtin":
        command = BOUNCE_COMMAND

    LOG.debug("pubhname: publishing hostname [%s]", msg)
    shell = not isinstance(command, (list, tuple))
    # capture=False, see comments in bug 1202758 and bug 1206164.
    util.log_time(logfunc=LOG.debug, msg="publishing hostname",
                  get_uptime=True, func=util.subp,
                  kwargs={'args': command, 'shell': shell, 'capture': False,
                          'env': env})


def crtfile_to_pubkey(fname, data=None):
    pipeline = ('openssl x509 -noout -pubkey < "$0" |'
                'ssh-keygen -i -m PKCS8 -f /dev/stdin')
    (out, _err) = util.subp(['sh', '-c', pipeline, fname],
                            capture=True, data=data)
    return out.rstrip()


def pubkeys_from_crt_files(flist):
    pubkeys = []
    errors = []
    for fname in flist:
        try:
            pubkeys.append(crtfile_to_pubkey(fname))
        except util.ProcessExecutionError:
            errors.append(fname)

    if errors:
        LOG.warn("failed to convert the crt files to pubkey: %s", errors)

    return pubkeys


def wait_for_files(flist, maxwait=60, naplen=.5):
    need = set(flist)
    waited = 0
    while waited < maxwait:
        need -= set([f for f in need if os.path.exists(f)])
        if len(need) == 0:
            return []
        time.sleep(naplen)
        waited += naplen
    return need


def write_files(datadir, files, dirmode=None):

    def _redact_password(cnt, fname):
        """Azure provides the UserPassword in plain text. So we redact it"""
        try:
            root = ET.fromstring(cnt)
            for elem in root.iter():
                if ('UserPassword' in elem.tag and
                   elem.text != DEF_PASSWD_REDACTION):
                    elem.text = DEF_PASSWD_REDACTION
            return ET.tostring(root)
        except Exception:
            LOG.critical("failed to redact userpassword in {}".format(fname))
            return cnt

    if not datadir:
        return
    if not files:
        files = {}
    util.ensure_dir(datadir, dirmode)
    for (name, content) in files.items():
        fname = os.path.join(datadir, name)
        if 'ovf-env.xml' in name:
            content = _redact_password(content, fname)
        util.write_file(filename=fname, content=content, mode=0o600)


def invoke_agent(cmd):
    # this is a function itself to simplify patching it for test
    if cmd:
        LOG.debug("invoking agent: %s", cmd)
        util.subp(cmd, shell=(not isinstance(cmd, list)))
    else:
        LOG.debug("not invoking agent")


def find_child(node, filter_func):
    ret = []
    if not node.hasChildNodes():
        return ret
    for child in node.childNodes:
        if filter_func(child):
            ret.append(child)
    return ret


def load_azure_ovf_pubkeys(sshnode):
    # This parses a 'SSH' node formatted like below, and returns
    # an array of dicts.
    #  [{'fp': '6BE7A7C3C8A8F4B123CCA5D0C2F1BE4CA7B63ED7',
    #    'path': 'where/to/go'}]
    #
    # <SSH><PublicKeys>
    #   <PublicKey><Fingerprint>ABC</FingerPrint><Path>/ABC</Path>
    #   ...
    # </PublicKeys></SSH>
    results = find_child(sshnode, lambda n: n.localName == "PublicKeys")
    if len(results) == 0:
        return []
    if len(results) > 1:
        raise BrokenAzureDataSource("Multiple 'PublicKeys'(%s) in SSH node" %
                                    len(results))

    pubkeys_node = results[0]
    pubkeys = find_child(pubkeys_node, lambda n: n.localName == "PublicKey")

    if len(pubkeys) == 0:
        return []

    found = []
    text_node = minidom.Document.TEXT_NODE

    for pk_node in pubkeys:
        if not pk_node.hasChildNodes():
            continue

        cur = {'fingerprint': "", 'path': "", 'value': ""}
        for child in pk_node.childNodes:
            if child.nodeType == text_node or not child.localName:
                continue

            name = child.localName.lower()

            if name not in cur.keys():
                continue

            if (len(child.childNodes) != 1 or
                    child.childNodes[0].nodeType != text_node):
                continue

            cur[name] = child.childNodes[0].wholeText.strip()
        found.append(cur)

    return found


def read_azure_ovf(contents):
    try:
        dom = minidom.parseString(contents)
    except Exception as e:
        raise BrokenAzureDataSource("invalid xml: %s" % e)

    results = find_child(dom.documentElement,
        lambda n: n.localName == "ProvisioningSection")

    if len(results) == 0:
        raise NonAzureDataSource("No ProvisioningSection")
    if len(results) > 1:
        raise BrokenAzureDataSource("found '%d' ProvisioningSection items" %
                                    len(results))
    provSection = results[0]

    lpcs_nodes = find_child(provSection,
        lambda n: n.localName == "LinuxProvisioningConfigurationSet")

    if len(results) == 0:
        raise NonAzureDataSource("No LinuxProvisioningConfigurationSet")
    if len(results) > 1:
        raise BrokenAzureDataSource("found '%d' %ss" %
                                    ("LinuxProvisioningConfigurationSet",
                                     len(results)))
    lpcs = lpcs_nodes[0]

    if not lpcs.hasChildNodes():
        raise BrokenAzureDataSource("no child nodes of configuration set")

    md_props = 'seedfrom'
    md = {'azure_data': {}}
    cfg = {}
    ud = ""
    password = None
    username = None

    for child in lpcs.childNodes:
        if child.nodeType == dom.TEXT_NODE or not child.localName:
            continue

        name = child.localName.lower()

        simple = False
        value = ""
        if (len(child.childNodes) == 1 and
                child.childNodes[0].nodeType == dom.TEXT_NODE):
            simple = True
            value = child.childNodes[0].wholeText

        attrs = dict([(k, v) for k, v in child.attributes.items()])

        # we accept either UserData or CustomData.  If both are present
        # then behavior is undefined.
        if name == "userdata" or name == "customdata":
            if attrs.get('encoding') in (None, "base64"):
                ud = base64.b64decode(''.join(value.split()))
            else:
                ud = value
        elif name == "username":
            username = value
        elif name == "userpassword":
            password = value
        elif name == "hostname":
            md['local-hostname'] = value
        elif name == "dscfg":
            if attrs.get('encoding') in (None, "base64"):
                dscfg = base64.b64decode(''.join(value.split()))
            else:
                dscfg = value
            cfg['datasource'] = {DS_NAME: util.load_yaml(dscfg, default={})}
        elif name == "ssh":
            cfg['_pubkeys'] = load_azure_ovf_pubkeys(child)
        elif name == "disablesshpasswordauthentication":
            cfg['ssh_pwauth'] = util.is_false(value)
        elif simple:
            if name in md_props:
                md[name] = value
            else:
                md['azure_data'][name] = value

    defuser = {}
    if username:
        defuser['name'] = username
    if password and DEF_PASSWD_REDACTION != password:
        defuser['passwd'] = encrypt_pass(password)
        defuser['lock_passwd'] = False

    if defuser:
        cfg['system_info'] = {'default_user': defuser}

    if 'ssh_pwauth' not in cfg and password:
        cfg['ssh_pwauth'] = True

    return (md, ud, cfg)


def encrypt_pass(password, salt_id="$6$"):
    return crypt.crypt(password, salt_id + util.rand_str(strlen=16))


def list_possible_azure_ds_devs():
    # return a sorted list of devices that might have a azure datasource
    devlist = []
    for fstype in ("iso9660", "udf"):
        devlist.extend(util.find_devs_with("TYPE=%s" % fstype))

    devlist.sort(reverse=True)
    return devlist


def load_azure_ds_dir(source_dir):
    ovf_file = os.path.join(source_dir, "ovf-env.xml")

    if not os.path.isfile(ovf_file):
        raise NonAzureDataSource("No ovf-env file found")

    with open(ovf_file, "rb") as fp:
        contents = fp.read()

    md, ud, cfg = read_azure_ovf(contents)
    return (md, ud, cfg, {'ovf-env.xml': contents})


def iid_from_shared_config(path):
    with open(path, "rb") as fp:
        content = fp.read()
    return iid_from_shared_config_content(content)


class BrokenAzureDataSource(Exception):
    pass


class NonAzureDataSource(Exception):
    pass


# Used to match classes to dependencies
datasources = [
  (DataSourceAzureNet, (sources.DEP_FILESYSTEM, sources.DEP_NETWORK)),
]


# Return a list of data sources that match this set of dependencies
def get_datasource_list(depends):
    return sources.list_from_depends(depends, datasources)