# Licensed to Elasticsearch B.V. under one or more contributor
# license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright
# ownership. Elasticsearch B.V. licenses this file to you under
# the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
import time
from itertools import chain
from platform import python_version
from ._version import __versionstr__
from .connection import Urllib3HttpConnection
from .connection_pool import ConnectionPool, DummyConnectionPool, EmptyConnectionPool
from .exceptions import (
ConnectionError,
ConnectionTimeout,
SerializationError,
TransportError,
)
from .serializer import DEFAULT_SERIALIZERS, Deserializer, JSONSerializer
from .utils import _client_meta_version
def get_host_info(node_info, host):
"""
Simple callback that takes the node info from `/_cluster/nodes` and a
parsed connection information and return the connection information. If
`None` is returned this node will be skipped.
Useful for filtering nodes (by proximity for example) or if additional
information needs to be provided for the :class:`~elasticsearch.Connection`
class. By default master only nodes are filtered out since they shouldn't
typically be used for API operations.
:arg node_info: node information from `/_cluster/nodes`
:arg host: connection information (host, port) extracted from the node info
"""
# ignore master only nodes
if node_info.get("roles", []) == ["master"]:
return None
return host
class Transport(object):
"""
Encapsulation of transport-related to logic. Handles instantiation of the
individual connections as well as creating a connection pool to hold them.
Main interface is the `perform_request` method.
"""
DEFAULT_CONNECTION_CLASS = Urllib3HttpConnection
def __init__(
self,
hosts,
connection_class=None,
connection_pool_class=ConnectionPool,
host_info_callback=get_host_info,
sniff_on_start=False,
sniffer_timeout=None,
sniff_timeout=0.1,
sniff_on_connection_fail=False,
serializer=JSONSerializer(),
serializers=None,
default_mimetype="application/json",
max_retries=3,
retry_on_status=(502, 503, 504),
retry_on_timeout=False,
send_get_body_as="GET",
meta_header=True,
**kwargs
):
"""
:arg hosts: list of dictionaries, each containing keyword arguments to
create a `connection_class` instance
:arg connection_class: subclass of :class:`~elasticsearch.Connection` to use
:arg connection_pool_class: subclass of :class:`~elasticsearch.ConnectionPool` to use
:arg host_info_callback: callback responsible for taking the node information from
`/_cluster/nodes`, along with already extracted information, and
producing a list of arguments (same as `hosts` parameter)
:arg sniff_on_start: flag indicating whether to obtain a list of nodes
from the cluster at startup time
:arg sniffer_timeout: number of seconds between automatic sniffs
:arg sniff_on_connection_fail: flag controlling if connection failure triggers a sniff
:arg sniff_timeout: timeout used for the sniff request - it should be a
fast api call and we are talking potentially to more nodes so we want
to fail quickly. Not used during initial sniffing (if
``sniff_on_start`` is on) when the connection still isn't
initialized.
:arg serializer: serializer instance
:arg serializers: optional dict of serializer instances that will be
used for deserializing data coming from the server. (key is the mimetype)
:arg default_mimetype: when no mimetype is specified by the server
response assume this mimetype, defaults to `'application/json'`
:arg max_retries: maximum number of retries before an exception is propagated
:arg retry_on_status: set of HTTP status codes on which we should retry
on a different node. defaults to ``(502, 503, 504)``
:arg retry_on_timeout: should timeout trigger a retry on different
node? (default `False`)
:arg send_get_body_as: for GET requests with body this option allows
you to specify an alternate way of execution for environments that
don't support passing bodies with GET requests. If you set this to
'POST' a POST method will be used instead, if to 'source' then the body
will be serialized and passed as a query parameter `source`.
:arg meta_header: If True will send the 'X-Elastic-Client-Meta' HTTP header containing
simple client metadata. Setting to False will disable the header. Defaults to True.
Any extra keyword arguments will be passed to the `connection_class`
when creating and instance unless overridden by that connection's
options provided as part of the hosts parameter.
"""
if connection_class is None:
connection_class = self.DEFAULT_CONNECTION_CLASS
if not isinstance(meta_header, bool):
raise TypeError("meta_header must be of type bool")
# serialization config
_serializers = DEFAULT_SERIALIZERS.copy()
# if a serializer has been specified, use it for deserialization as well
_serializers[serializer.mimetype] = serializer
# if custom serializers map has been supplied, override the defaults with it
if serializers:
_serializers.update(serializers)
# create a deserializer with our config
self.deserializer = Deserializer(_serializers, default_mimetype)
self.max_retries = max_retries
self.retry_on_timeout = retry_on_timeout
self.retry_on_status = retry_on_status
self.send_get_body_as = send_get_body_as
self.meta_header = meta_header
# data serializer
self.serializer = serializer
# store all strategies...
self.connection_pool_class = connection_pool_class
self.connection_class = connection_class
# ...save kwargs to be passed to the connections
self.kwargs = kwargs
self.hosts = hosts
# Start with an empty pool specifically for `AsyncTransport`.
# It should never be used, will be replaced on first call to
# .set_connections()
self.connection_pool = EmptyConnectionPool()
if hosts:
# ...and instantiate them
self.set_connections(hosts)
# retain the original connection instances for sniffing
self.seed_connections = list(self.connection_pool.connections[:])
else:
self.seed_connections = []
# Don't enable sniffing on Cloud instances.
if kwargs.get("cloud_id", False):
sniff_on_start = False
sniff_on_connection_fail = False
# sniffing data
self.sniffer_timeout = sniffer_timeout
self.sniff_on_start = sniff_on_start
self.sniff_on_connection_fail = sniff_on_connection_fail
self.last_sniff = time.time()
self.sniff_timeout = sniff_timeout
# callback to construct host dict from data in /_cluster/nodes
self.host_info_callback = host_info_callback
if sniff_on_start:
self.sniff_hosts(True)
# Create the default metadata for the x-elastic-client-meta
# HTTP header. Only requires adding the (service, service_version)
# tuple to the beginning of the client_meta
self._client_meta = (
("es", _client_meta_version(__versionstr__)),
("py", _client_meta_version(python_version())),
("t", _client_meta_version(__versionstr__)),
)
# Grab the 'HTTP_CLIENT_META' property from the connection class
http_client_meta = getattr(connection_class, "HTTP_CLIENT_META", None)
if http_client_meta:
self._client_meta += (http_client_meta,)
def add_connection(self, host):
"""
Create a new :class:`~elasticsearch.Connection` instance and add it to the pool.
:arg host: kwargs that will be used to create the instance
"""
self.hosts.append(host)
self.set_connections(self.hosts)
def set_connections(self, hosts):
"""
Instantiate all the connections and create new connection pool to hold them.
Tries to identify unchanged hosts and re-use existing
:class:`~elasticsearch.Connection` instances.
:arg hosts: same as `__init__`
"""
# construct the connections
def _create_connection(host):
# if this is not the initial setup look at the existing connection
# options and identify connections that haven't changed and can be
# kept around.
if hasattr(self, "connection_pool"):
for (connection, old_host) in self.connection_pool.connection_opts:
if old_host == host:
return connection
# previously unseen params, create new connection
kwargs = self.kwargs.copy()
kwargs.update(host)
return self.connection_class(**kwargs)
connections = map(_create_connection, hosts)
connections = list(zip(connections, hosts))
if len(connections) == 1:
self.connection_pool = DummyConnectionPool(connections)
else:
# pass the hosts dicts to the connection pool to optionally extract parameters from
self.connection_pool = self.connection_pool_class(
connections, **self.kwargs
)
def get_connection(self):
"""
Retrieve a :class:`~elasticsearch.Connection` instance from the
:class:`~elasticsearch.ConnectionPool` instance.
"""
if self.sniffer_timeout:
if time.time() >= self.last_sniff + self.sniffer_timeout:
self.sniff_hosts()
return self.connection_pool.get_connection()
def _get_sniff_data(self, initial=False):
"""
Perform the request to get sniffing information. Returns a list of
dictionaries (one per node) containing all the information from the
cluster.
It also sets the last_sniff attribute in case of a successful attempt.
In rare cases it might be possible to override this method in your
custom Transport class to serve data from alternative source like
configuration management.
"""
previous_sniff = self.last_sniff
try:
# reset last_sniff timestamp
self.last_sniff = time.time()
# go through all current connections as well as the
# seed_connections for good measure
for c in chain(self.connection_pool.connections, self.seed_connections):
try:
# use small timeout for the sniffing request, should be a fast api call
_, headers, node_info = c.perform_request(
"GET",
"/_nodes/_all/http",
timeout=self.sniff_timeout if not initial else None,
)
node_info = self.deserializer.loads(
node_info, headers.get("content-type")
)
break
except (ConnectionError, SerializationError):
pass
else:
raise TransportError("N/A", "Unable to sniff hosts.")
except Exception:
# keep the previous value on error
self.last_sniff = previous_sniff
raise
return list(node_info["nodes"].values())
def _get_host_info(self, host_info):
host = {}
address = host_info.get("http", {}).get("publish_address")
# malformed or no address given
if not address or ":" not in address:
return None
if "/" in address:
# Support 7.x host/ip:port behavior where http.publish_host has been set.
fqdn, ipaddress = address.split("/", 1)
host["host"] = fqdn
_, host["port"] = ipaddress.rsplit(":", 1)
host["port"] = int(host["port"])
else:
host["host"], host["port"] = address.rsplit(":", 1)
host["port"] = int(host["port"])
return self.host_info_callback(host_info, host)
def sniff_hosts(self, initial=False):
"""
Obtain a list of nodes from the cluster and create a new connection
pool using the information retrieved.
To extract the node connection parameters use the ``nodes_to_host_callback``.
:arg initial: flag indicating if this is during startup
(``sniff_on_start``), ignore the ``sniff_timeout`` if ``True``
"""
node_info = self._get_sniff_data(initial)
hosts = list(filter(None, (self._get_host_info(n) for n in node_info)))
# we weren't able to get any nodes or host_info_callback blocked all -
# raise error.
if not hosts:
raise TransportError(
"N/A", "Unable to sniff hosts - no viable hosts found."
)
self.set_connections(hosts)
def mark_dead(self, connection):
"""
Mark a connection as dead (failed) in the connection pool. If sniffing
on failure is enabled this will initiate the sniffing process.
:arg connection: instance of :class:`~elasticsearch.Connection` that failed
"""
# mark as dead even when sniffing to avoid hitting this host during the sniff process
self.connection_pool.mark_dead(connection)
if self.sniff_on_connection_fail:
self.sniff_hosts()
def perform_request(self, method, url, headers=None, params=None, body=None):
"""
Perform the actual request. Retrieve a connection from the connection
pool, pass all the information to it's perform_request method and
return the data.
If an exception was raised, mark the connection as failed and retry (up
to `max_retries` times).
If the operation was successful and the connection used was previously
marked as dead, mark it as live, resetting it's failure count.
:arg method: HTTP method to use
:arg url: absolute url (without host) to target
:arg headers: dictionary of headers, will be handed over to the
underlying :class:`~elasticsearch.Connection` class
:arg params: dictionary of query parameters, will be handed over to the
underlying :class:`~elasticsearch.Connection` class for serialization
:arg body: body of the request, will be serialized using serializer and
passed to the connection
"""
method, headers, params, body, ignore, timeout = self._resolve_request_args(
method, headers, params, body
)
for attempt in range(self.max_retries + 1):
connection = self.get_connection()
try:
status, headers_response, data = connection.perform_request(
method,
url,
params,
body,
headers=headers,
ignore=ignore,
timeout=timeout,
)
except TransportError as e:
if method == "HEAD" and e.status_code == 404:
return False
retry = False
if isinstance(e, ConnectionTimeout):
retry = self.retry_on_timeout
elif isinstance(e, ConnectionError):
retry = True
elif e.status_code in self.retry_on_status:
retry = True
if retry:
try:
# only mark as dead if we are retrying
self.mark_dead(connection)
except TransportError:
# If sniffing on failure, it could fail too. Catch the
# exception not to interrupt the retries.
pass
# raise exception on last retry
if attempt == self.max_retries:
raise e
else:
raise e
else:
# connection didn't fail, confirm it's live status
self.connection_pool.mark_live(connection)
if method == "HEAD":
return 200 <= status < 300
if data:
data = self.deserializer.loads(
data, headers_response.get("content-type")
)
return data
def close(self):
"""
Explicitly closes connections
"""
self.connection_pool.close()
def _resolve_request_args(self, method, headers, params, body):
"""Resolves parameters for .perform_request()"""
if body is not None:
body = self.serializer.dumps(body)
# some clients or environments don't support sending GET with body
if method in ("HEAD", "GET") and self.send_get_body_as != "GET":
# send it as post instead
if self.send_get_body_as == "POST":
method = "POST"
# or as source parameter
elif self.send_get_body_as == "source":
if params is None:
params = {}
params["source"] = body
body = None
if body is not None:
try:
body = body.encode("utf-8", "surrogatepass")
except (UnicodeDecodeError, AttributeError):
# bytes/str - no need to re-encode
pass
ignore = ()
timeout = None
if params:
timeout = params.pop("request_timeout", None)
ignore = params.pop("ignore", ())
if isinstance(ignore, int):
ignore = (ignore,)
client_meta = params.pop("__elastic_client_meta", ())
else:
client_meta = ()
if self.meta_header:
headers = headers or {}
client_meta = self._client_meta + client_meta
headers["x-elastic-client-meta"] = ",".join(
"%s=%s" % (k, v) for k, v in client_meta
)
return method, headers, params, body, ignore, timeout