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Filename : DataSourceScaleway.py
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# Author: Julien Castets <castets.j@gmail.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

# Scaleway API:
# https://developer.scaleway.com/#metadata

import json
import os
import socket
import time

import requests

# pylint fails to import the two modules below.
# These are imported via requests.packages rather than urllib3 because:
#  a.) the provider of the requests package should ensure that urllib3
#      contained in it is consistent/correct.
#  b.) cloud-init does not specifically have a dependency on urllib3
#
# For future reference, see:
#   https://github.com/kennethreitz/requests/pull/2375
#   https://github.com/requests/requests/issues/4104
# pylint: disable=E0401
from requests.packages.urllib3.connection import HTTPConnection
from requests.packages.urllib3.poolmanager import PoolManager

from cloudinit import dmi
from cloudinit import log as logging
from cloudinit import sources
from cloudinit import url_helper
from cloudinit import util
from cloudinit import net
from cloudinit.net.dhcp import EphemeralDHCPv4, NoDHCPLeaseError
from cloudinit.event import EventType

LOG = logging.getLogger(__name__)

DS_BASE_URL = 'http://169.254.42.42'

BUILTIN_DS_CONFIG = {
    'metadata_url': DS_BASE_URL + '/conf?format=json',
    'userdata_url': DS_BASE_URL + '/user_data/cloud-init',
    'vendordata_url': DS_BASE_URL + '/vendor_data/cloud-init'
}

DEF_MD_RETRIES = 5
DEF_MD_TIMEOUT = 10


def on_scaleway():
    """
    There are three ways to detect if you are on Scaleway:

    * check DMI data: not yet implemented by Scaleway, but the check is made to
      be future-proof.
    * the initrd created the file /var/run/scaleway.
    * "scaleway" is in the kernel cmdline.
    """
    vendor_name = dmi.read_dmi_data('system-manufacturer')
    if vendor_name == 'Scaleway':
        return True

    if os.path.exists('/var/run/scaleway'):
        return True

    cmdline = util.get_cmdline()
    if 'scaleway' in cmdline:
        return True

    return False


class SourceAddressAdapter(requests.adapters.HTTPAdapter):
    """
    Adapter for requests to choose the local address to bind to.
    """
    def __init__(self, source_address, **kwargs):
        self.source_address = source_address
        super(SourceAddressAdapter, self).__init__(**kwargs)

    def init_poolmanager(self, connections, maxsize, block=False):
        socket_options = HTTPConnection.default_socket_options + [
            (socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
        ]
        self.poolmanager = PoolManager(num_pools=connections,
                                       maxsize=maxsize,
                                       block=block,
                                       source_address=self.source_address,
                                       socket_options=socket_options)


def query_data_api_once(api_address, timeout, requests_session):
    """
    Retrieve user data or vendor data.

    Scaleway user/vendor data API returns HTTP/404 if user/vendor data is not
    set.

    This function calls `url_helper.readurl` but instead of considering
    HTTP/404 as an error that requires a retry, it considers it as empty
    user/vendor data.

    Also, be aware the user data/vendor API requires the source port to be
    below 1024 to ensure the client is root (since non-root users can't bind
    ports below 1024). If requests raises ConnectionError (EADDRINUSE), the
    caller should retry to call this function on an other port.
    """
    try:
        resp = url_helper.readurl(
            api_address,
            data=None,
            timeout=timeout,
            # It's the caller's responsability to recall this function in case
            # of exception. Don't let url_helper.readurl() retry by itself.
            retries=0,
            session=requests_session,
            # If the error is a HTTP/404 or a ConnectionError, go into raise
            # block below and don't bother retrying.
            exception_cb=lambda _, exc: exc.code != 404 and (
                not isinstance(exc.cause, requests.exceptions.ConnectionError)
            )
        )
        return util.decode_binary(resp.contents)
    except url_helper.UrlError as exc:
        # Empty user data.
        if exc.code == 404:
            return None
        raise


def query_data_api(api_type, api_address, retries, timeout):
    """Get user or vendor data.

    Handle the retrying logic in case the source port is used.

    Scaleway metadata service requires the source port of the client to
    be a privileged port (<1024).  This is done to ensure that only a
    privileged user on the system can access the metadata service.
    """
    # Query user/vendor data. Try to make a request on the first privileged
    # port available.
    for port in range(1, max(retries, 2)):
        try:
            LOG.debug(
                'Trying to get %s data (bind on port %d)...',
                api_type, port
            )
            requests_session = requests.Session()
            requests_session.mount(
                'http://',
                SourceAddressAdapter(source_address=('0.0.0.0', port))
            )
            data = query_data_api_once(
                api_address,
                timeout=timeout,
                requests_session=requests_session
            )
            LOG.debug('%s-data downloaded', api_type)
            return data

        except url_helper.UrlError as exc:
            # Local port already in use or HTTP/429.
            LOG.warning('Error while trying to get %s data: %s', api_type, exc)
            time.sleep(5)
            last_exc = exc
            continue

    # Max number of retries reached.
    raise last_exc


class DataSourceScaleway(sources.DataSource):
    dsname = "Scaleway"
    update_events = {'network': [EventType.BOOT_NEW_INSTANCE, EventType.BOOT]}

    def __init__(self, sys_cfg, distro, paths):
        super(DataSourceScaleway, self).__init__(sys_cfg, distro, paths)

        self.ds_cfg = util.mergemanydict([
            util.get_cfg_by_path(sys_cfg, ["datasource", "Scaleway"], {}),
            BUILTIN_DS_CONFIG
        ])

        self.metadata_address = self.ds_cfg['metadata_url']
        self.userdata_address = self.ds_cfg['userdata_url']
        self.vendordata_address = self.ds_cfg['vendordata_url']

        self.retries = int(self.ds_cfg.get('retries', DEF_MD_RETRIES))
        self.timeout = int(self.ds_cfg.get('timeout', DEF_MD_TIMEOUT))
        self._fallback_interface = None
        self._network_config = sources.UNSET

    def _crawl_metadata(self):
        resp = url_helper.readurl(self.metadata_address,
                                  timeout=self.timeout,
                                  retries=self.retries)
        self.metadata = json.loads(util.decode_binary(resp.contents))

        self.userdata_raw = query_data_api(
            'user-data', self.userdata_address,
            self.retries, self.timeout
        )
        self.vendordata_raw = query_data_api(
            'vendor-data', self.vendordata_address,
            self.retries, self.timeout
        )

    def _get_data(self):
        if not on_scaleway():
            return False

        if self._fallback_interface is None:
            self._fallback_interface = net.find_fallback_nic()
        try:
            with EphemeralDHCPv4(self._fallback_interface):
                util.log_time(
                    logfunc=LOG.debug, msg='Crawl of metadata service',
                    func=self._crawl_metadata)
        except (NoDHCPLeaseError) as e:
            util.logexc(LOG, str(e))
            return False
        return True

    @property
    def network_config(self):
        """
        Configure networking according to data received from the
        metadata API.
        """
        if self._network_config is None:
            LOG.warning('Found None as cached _network_config. '
                        'Resetting to %s', sources.UNSET)
            self._network_config = sources.UNSET

        if self._network_config != sources.UNSET:
            return self._network_config

        if self._fallback_interface is None:
            self._fallback_interface = net.find_fallback_nic()

        netcfg = {'type': 'physical', 'name': '%s' % self._fallback_interface}
        subnets = [{'type': 'dhcp4'}]
        if self.metadata['ipv6']:
            subnets += [{'type': 'static',
                         'address': '%s' % self.metadata['ipv6']['address'],
                         'gateway': '%s' % self.metadata['ipv6']['gateway'],
                         'netmask': '%s' % self.metadata['ipv6']['netmask'],
                         }]
        netcfg['subnets'] = subnets
        self._network_config = {'version': 1, 'config': [netcfg]}
        return self._network_config

    @property
    def launch_index(self):
        return None

    def get_instance_id(self):
        return self.metadata['id']

    def get_public_ssh_keys(self):
        ssh_keys = [key['key'] for key in self.metadata['ssh_public_keys']]

        akeypre = "AUTHORIZED_KEY="
        plen = len(akeypre)
        for tag in self.metadata.get('tags', []):
            if not tag.startswith(akeypre):
                continue
            ssh_keys.append(tag[:plen].replace("_", " "))

        return ssh_keys

    def get_hostname(self, fqdn=False, resolve_ip=False, metadata_only=False):
        return self.metadata['hostname']

    @property
    def availability_zone(self):
        return None

    @property
    def region(self):
        return None


datasources = [
    (DataSourceScaleway, (sources.DEP_FILESYSTEM,)),
]


def get_datasource_list(depends):
    return sources.list_from_depends(depends, datasources)