failover support for elastic-sync-notifier and elasticsearch

deprecates herald options `elastic_host`, `elastic_port`, `elastic_notifier_host`, and `elastic_notifier_port` in favor of the single new `elastic_services` option

hub/herald/env.py

@@ -1,29 +1,38 @@
 import re
+from collections import deque
 from hub.env import Env
 
+ELASTIC_SERVICES_REGEX = re.compile("(([\d|\.]|[^,:\/])*:\d*\/([\d|\.]|[^,:\/])*:\d*,?)*")
+
+
+def parse_es_services(elastic_services_arg: str):
+    match = ELASTIC_SERVICES_REGEX.match(elastic_services_arg)
+    if not match:
+        return []
+    matching = match.group()
+    services = [item.split('/') for item in matching.split(',') if item]
+    return [
+        ((es.split(':')[0], int(es.split(':')[1])), (notifier.split(':')[0], int(notifier.split(':')[1])))
+        for (es, notifier) in services
+    ]
+
 
 class ServerEnv(Env):
     def __init__(self, db_dir=None, max_query_workers=None, chain=None, reorg_limit=None,
                  prometheus_port=None, cache_all_tx_hashes=None, cache_all_claim_txos=None,
-                 daemon_url=None, host=None, elastic_host=None, elastic_port=None, es_index_prefix=None,
+                 daemon_url=None, host=None, elastic_services=None, es_index_prefix=None,
                  tcp_port=None, udp_port=None, banner_file=None, allow_lan_udp=None, country=None,
                  payment_address=None, donation_address=None, max_send=None, max_receive=None, max_sessions=None,
                  session_timeout=None, drop_client=None, description=None, daily_fee=None,
-                 database_query_timeout=None, elastic_notifier_host=None, elastic_notifier_port=None,
+                 database_query_timeout=None, blocking_channel_ids=None, filtering_channel_ids=None, peer_hubs=None,
-                 blocking_channel_ids=None, filtering_channel_ids=None, peer_hubs=None, peer_announce=None,
+                 peer_announce=None, index_address_status=None, address_history_cache_size=None, daemon_ca_path=None,
-                 index_address_status=None, address_history_cache_size=None, daemon_ca_path=None,
                  merkle_cache_size=None, resolved_url_cache_size=None, tx_cache_size=None,
                  history_tx_cache_size=None, largest_address_history_cache_size=None):
         super().__init__(db_dir, max_query_workers, chain, reorg_limit, prometheus_port, cache_all_tx_hashes,
                          cache_all_claim_txos, blocking_channel_ids, filtering_channel_ids, index_address_status)
         self.daemon_url = daemon_url if daemon_url is not None else self.required('DAEMON_URL')
         self.host = host if host is not None else self.default('HOST', 'localhost')
-        self.elastic_host = elastic_host if elastic_host is not None else self.default('ELASTIC_HOST', 'localhost')
+        self.elastic_services = deque(parse_es_services(elastic_services or 'localhost:9200/localhost:19080'))
-        self.elastic_port = elastic_port if elastic_port is not None else self.integer('ELASTIC_PORT', 9200)
-        self.elastic_notifier_host = elastic_notifier_host if elastic_notifier_host is not None else self.default(
-            'ELASTIC_NOTIFIER_HOST', 'localhost')
-        self.elastic_notifier_port = elastic_notifier_port if elastic_notifier_port is not None else self.integer(
-            'ELASTIC_NOTIFIER_PORT', 19080)
         self.es_index_prefix = es_index_prefix if es_index_prefix is not None else self.default('ES_INDEX_PREFIX', '')
         # Server stuff
         self.tcp_port = tcp_port if tcp_port is not None else self.integer('TCP_PORT', None)
@@ -93,15 +102,13 @@ class ServerEnv(Env):
                             help="Regex used for blocking clients")
         parser.add_argument('--session_timeout', type=int, default=cls.integer('SESSION_TIMEOUT', 600),
                             help="Session inactivity timeout")
-        parser.add_argument('--elastic_host', default=cls.default('ELASTIC_HOST', 'localhost'), type=str,
+        parser.add_argument('--elastic_services',
-                            help="Hostname or ip address of the elasticsearch instance to connect to. "
+                            default=cls.default('ELASTIC_SERVICES', 'localhost:9200/localhost:19080'), type=str,
-                                 "Can be set in env with 'ELASTIC_HOST'")
+                            help="Hosts and ports for elastic search and the scribe elastic sync notifier. "
-        parser.add_argument('--elastic_port', default=cls.integer('ELASTIC_PORT', 9200), type=int,
+                                 "Given as a comma separated list without spaces of items in the format "
-                            help="Elasticsearch port to connect to. Can be set in env with 'ELASTIC_PORT'")
+                                 "<elastic host>:<elastic port>/<notifier host>:<notifier port> . "
-        parser.add_argument('--elastic_notifier_host', default=cls.default('ELASTIC_NOTIFIER_HOST', 'localhost'),
+                                 "Defaults to 'localhost:9200/localhost:19080'. "
-                            type=str, help='elasticsearch sync notifier host, defaults to localhost')
+                                 "Can be set in env with 'ELASTIC_SERVICES'")
-        parser.add_argument('--elastic_notifier_port', default=cls.integer('ELASTIC_NOTIFIER_PORT', 19080), type=int,
-                            help='elasticsearch sync notifier port')
         parser.add_argument('--es_index_prefix', default=cls.default('ES_INDEX_PREFIX', ''), type=str)
         parser.add_argument('--allow_lan_udp', action='store_true',
                             help="Reply to clients on the local network", default=cls.boolean('ALLOW_LAN_UDP', False))
@@ -141,8 +148,8 @@ class ServerEnv(Env):
     @classmethod
     def from_arg_parser(cls, args):
         return cls(
-            db_dir=args.db_dir, daemon_url=args.daemon_url, host=args.host, elastic_host=args.elastic_host,
+            db_dir=args.db_dir, daemon_url=args.daemon_url, host=args.host, elastic_services=args.elastic_services,
-            elastic_port=args.elastic_port, max_query_workers=args.max_query_workers, chain=args.chain,
+            max_query_workers=args.max_query_workers, chain=args.chain,
             es_index_prefix=args.es_index_prefix, reorg_limit=args.reorg_limit, tcp_port=args.tcp_port,
             udp_port=args.udp_port, prometheus_port=args.prometheus_port, banner_file=args.banner_file,
             allow_lan_udp=args.allow_lan_udp, cache_all_tx_hashes=args.cache_all_tx_hashes,
@@ -151,8 +158,7 @@ class ServerEnv(Env):
             max_sessions=args.max_sessions, session_timeout=args.session_timeout,
             drop_client=args.drop_client, description=args.description, daily_fee=args.daily_fee,
             database_query_timeout=args.query_timeout_ms, blocking_channel_ids=args.blocking_channel_ids,
-            filtering_channel_ids=args.filtering_channel_ids, elastic_notifier_host=args.elastic_notifier_host,
+            filtering_channel_ids=args.filtering_channel_ids, index_address_status=args.index_address_statuses,
-            elastic_notifier_port=args.elastic_notifier_port, index_address_status=args.index_address_statuses,
             address_history_cache_size=args.address_history_cache_size, daemon_ca_path=args.daemon_ca_path,
             merkle_cache_size=args.merkle_cache_size, resolved_url_cache_size=args.resolved_url_cache_size,
             tx_cache_size=args.tx_cache_size, history_tx_cache_size=args.history_tx_cache_size,

hub/herald/search.py

@@ -3,7 +3,7 @@ import asyncio
 from bisect import bisect_right
 from collections import Counter, deque
 from operator import itemgetter
-from typing import Optional, List, TYPE_CHECKING
+from typing import Optional, List, TYPE_CHECKING, Deque, Tuple
 
 from elasticsearch import AsyncElasticsearch, NotFoundError, ConnectionError
 from hub.schema.result import Censor, Outputs
@@ -29,8 +29,9 @@ class StreamResolution(str):
 class SearchIndex:
     VERSION = 1
 
-    def __init__(self, hub_db: 'SecondaryDB', index_prefix: str, search_timeout=3.0, elastic_host='localhost',
+    def __init__(self, hub_db: 'SecondaryDB', index_prefix: str, search_timeout=3.0,
-                 elastic_port=9200, timeout_counter: Optional['PrometheusCounter'] = None):
+                 elastic_services: Optional[Deque[Tuple[Tuple[str, int], Tuple[str, int]]]] = None,
+                 timeout_counter: Optional['PrometheusCounter'] = None):
         self.hub_db = hub_db
         self.search_timeout = search_timeout
         self.timeout_counter: Optional['PrometheusCounter'] = timeout_counter
@@ -41,8 +42,8 @@ class SearchIndex:
         self.logger = logging.getLogger(__name__)
         self.claim_cache = LRUCache(2 ** 15)
         self.search_cache = LRUCache(2 ** 17)
-        self._elastic_host = elastic_host
+        self._elastic_services = elastic_services
-        self._elastic_port = elastic_port
+        self.lost_connection = asyncio.Event()
 
     async def get_index_version(self) -> int:
         try:
@@ -59,7 +60,7 @@ class SearchIndex:
     async def start(self) -> bool:
         if self.sync_client:
             return False
-        hosts = [{'host': self._elastic_host, 'port': self._elastic_port}]
+        hosts = [{'host': self._elastic_services[0][0][0], 'port': self._elastic_services[0][0][1]}]
         self.sync_client = AsyncElasticsearch(hosts, timeout=self.sync_timeout)
         self.search_client = AsyncElasticsearch(hosts, timeout=self.search_timeout+1)
         while True:

hub/herald/service.py

@@ -28,9 +28,10 @@ class HubServerService(BlockchainReaderService):
         self.status_server = StatusServer()
         self.daemon = LBCDaemon(env.coin, env.daemon_url, daemon_ca_path=env.daemon_ca_path)  # only needed for broadcasting txs
         self.mempool = HubMemPool(self.env.coin, self.db)
+
         self.search_index = SearchIndex(
             self.db, self.env.es_index_prefix, self.env.database_query_timeout,
-            elastic_host=env.elastic_host, elastic_port=env.elastic_port,
+            elastic_services=self.env.elastic_services,
             timeout_counter=self.interrupt_count_metric
         )
 
@@ -43,7 +44,7 @@ class HubServerService(BlockchainReaderService):
         self.mempool.session_manager = self.session_manager
         self.es_notifications = asyncio.Queue()
         self.es_notification_client = ElasticNotifierClientProtocol(
-            self.es_notifications, self.env.elastic_notifier_host, self.env.elastic_notifier_port
+            self.es_notifications, self.env.elastic_services
         )
         self.synchronized = asyncio.Event()
         self._es_height = None
@@ -129,8 +130,44 @@ class HubServerService(BlockchainReaderService):
                     self.log.info("es and reader are not yet in sync (block %s vs %s)", self._es_height,
                                   self.db.db_height)
         finally:
+            self.log.warning("closing es sync notification loop at %s", self._es_height)
             self.es_notification_client.close()
 
+    async def failover_elastic_services(self, synchronized: asyncio.Event):
+        first_connect = True
+        if not self.es_notification_client.lost_connection.is_set():
+            synchronized.set()
+
+        while True:
+            try:
+                await self.es_notification_client.lost_connection.wait()
+                if not first_connect:
+                    self.log.warning("lost connection to scribe-elastic-sync notifier (%s:%i)",
+                                     self.es_notification_client.host, self.es_notification_client.port)
+                await self.es_notification_client.connect()
+                first_connect = False
+                synchronized.set()
+                self.log.info("connected to es notifier on %s:%i", self.es_notification_client.host,
+                              self.es_notification_client.port)
+                await self.search_index.start()
+            except Exception as e:
+                if not isinstance(e, asyncio.CancelledError):
+                    self.log.warning("lost connection to scribe-elastic-sync notifier")
+                    await self.search_index.stop()
+                    self.search_index.clear_caches()
+                    if len(self.env.elastic_services) > 1:
+                        self.env.elastic_services.rotate(-1)
+                        self.log.warning("attempting to failover to %s:%i", self.es_notification_client.host,
+                                         self.es_notification_client.port)
+                        await asyncio.sleep(1)
+                    else:
+                        self.log.warning("waiting 30s for scribe-elastic-sync notifier to become available (%s:%i)",
+                                         self.es_notification_client.host, self.es_notification_client.port)
+                        await asyncio.sleep(30)
+                else:
+                    self.log.info("stopping the notifier loop")
+                    raise e
+
     async def start_status_server(self):
         if self.env.udp_port and int(self.env.udp_port):
             await self.status_server.start(
@@ -140,14 +177,13 @@ class HubServerService(BlockchainReaderService):
 
     def _iter_start_tasks(self):
         yield self.start_status_server()
-        yield self.start_cancellable(self.es_notification_client.maintain_connection)
+        yield self.start_cancellable(self.receive_es_notifications)
+        yield self.start_cancellable(self.failover_elastic_services)
         yield self.start_cancellable(self.mempool.send_notifications_forever)
         yield self.start_cancellable(self.refresh_blocks_forever)
         yield self.finished_initial_catch_up.wait()
         self.block_count_metric.set(self.last_state.height)
         yield self.start_prometheus()
-        yield self.start_cancellable(self.receive_es_notifications)
-        yield self.search_index.start()
         yield self.start_cancellable(self.session_manager.serve, self.mempool)
 
     def _iter_stop_tasks(self):

hub/notifier_protocol.py

@@ -2,6 +2,7 @@ import typing
 import struct
 import asyncio
 import logging
+from typing import Deque, Tuple
 
 
 log = logging.getLogger(__name__)
@@ -31,52 +32,39 @@ class ElasticNotifierProtocol(asyncio.Protocol):
 class ElasticNotifierClientProtocol(asyncio.Protocol):
     """notifies the reader when ES has written updates"""
 
-    def __init__(self, notifications: asyncio.Queue, host: str, port: int):
+    def __init__(self, notifications: asyncio.Queue, notifier_hosts: Deque[Tuple[Tuple[str, int], Tuple[str, int]]]):
+        assert len(notifier_hosts) > 0, 'no elastic notifier clients given'
         self.notifications = notifications
         self.transport: typing.Optional[asyncio.Transport] = None
-        self.host = host
+        self._notifier_hosts = notifier_hosts
-        self.port = port
+        self.lost_connection = asyncio.Event()
-        self._lost_connection = asyncio.Event()
+        self.lost_connection.set()
-        self._lost_connection.set()
+
+    @property
+    def host(self):
+        return self._notifier_hosts[0][1][0]
+
+    @property
+    def port(self):
+        return self._notifier_hosts[0][1][1]
 
     async def connect(self):
-        if self._lost_connection.is_set():
+        if self.lost_connection.is_set():
             await asyncio.get_event_loop().create_connection(
                 lambda: self, self.host, self.port
             )
 
-    async def maintain_connection(self, synchronized: asyncio.Event):
-        first_connect = True
-        if not self._lost_connection.is_set():
-            synchronized.set()
-        while True:
-            try:
-                await self._lost_connection.wait()
-                if not first_connect:
-                    log.warning("lost connection to scribe-elastic-sync notifier")
-                await self.connect()
-                first_connect = False
-                synchronized.set()
-                log.info("connected to es notifier")
-            except Exception as e:
-                if not isinstance(e, asyncio.CancelledError):
-                    log.warning("waiting 30s for scribe-elastic-sync notifier to become available (%s:%i)", self.host, self.port)
-                    await asyncio.sleep(30)
-                else:
-                    log.info("stopping the notifier loop")
-                    raise e
-
     def close(self):
         if self.transport and not self.transport.is_closing():
             self.transport.close()
 
     def connection_made(self, transport):
         self.transport = transport
-        self._lost_connection.clear()
+        self.lost_connection.clear()
 
     def connection_lost(self, exc) -> None:
         self.transport = None
-        self._lost_connection.set()
+        self.lost_connection.set()
 
     def data_received(self, data: bytes) -> None:
         try: