test.py: improve seeds for new servers

Instead of only using last started server as seed, use all started
servers as seed for new servers.

This also avoids tracking last server's state.

Pass empty list instead of None.

Signed-off-by: Alejo Sanchez <alejo.sanchez@scylladb.com>

test.py

@@ -337,7 +337,7 @@ class PythonTestSuite(TestSuite):
 
     def topology_for_class(self, class_name: str, cfg: dict) -> Callable[[], Awaitable]:
 
-        def create_server(cluster_name, seed):
+        def create_server(cluster_name: str, seeds: List[str]):
             cmdline_options = self.cfg.get("extra_scylla_cmdline_options", [])
             config_options = self.cfg.get("extra_scylla_config_options",
                                           {"authenticator": "PasswordAuthenticator",
@@ -349,7 +349,7 @@ class PythonTestSuite(TestSuite):
                 vardir=os.path.join(self.options.tmpdir, self.mode),
                 host_registry=self.hosts,
                 cluster_name=cluster_name,
-                seed=seed,
+                seeds=seeds,
                 cmdline_options=cmdline_options,
                 config_options=config_options)
 

test/pylib/scylla_cluster.py

@@ -107,7 +107,7 @@ class ScyllaServer:
 
     def __init__(self, exe: str, vardir: str,
                  host_registry,
-                 cluster_name: str, seed: Optional[str],
+                 cluster_name: str, seeds: List[str],
                  cmdline_options: List[str],
                  config_options: Dict[str, str]) -> None:
         self.exe = pathlib.Path(exe).resolve()
@@ -116,7 +116,7 @@ class ScyllaServer:
         self.cmdline_options = cmdline_options
         self.cluster_name = cluster_name
         self.hostname = ""
-        self.seed = seed
+        self.seeds = seeds
         self.cmd: Optional[asyncio.subprocess.Process] = None
         self.log_savepoint = 0
         self.control_cluster: Optional[Cluster] = None
@@ -167,8 +167,8 @@ class ScyllaServer:
         # Scylla assumes all instances of a cluster use the same port,
         # so each instance needs an own IP address.
         self.hostname = await self.host_registry.lease_host()
-        if not self.seed:
-            self.seed = self.hostname
+        if not self.seeds:
+            self.seeds = [self.hostname]
         # Use the last part in host IP 127.151.3.27 -> 27
         # There can be no duplicates within the same test run
         # thanks to how host registry registers subnets, and
@@ -193,7 +193,7 @@ class ScyllaServer:
         fmt = {
               "cluster_name": self.cluster_name,
               "host": self.hostname,
-              "seeds": self.seed,
+              "seeds": ",".join(self.seeds),
               "workdir": self.workdir,
               "authenticator": self.authenticator,
               "authorizer": self.authorizer
@@ -329,10 +329,10 @@ Check the log files:
         state. Helps quickly propagate tokens and speed up node boot if the
         previous state propagation was missed."""
         auth = PlainTextAuthProvider(username='cassandra', password='cassandra')
-        profile = ExecutionProfile(load_balancing_policy=WhiteListRoundRobinPolicy([self.seed]),
+        profile = ExecutionProfile(load_balancing_policy=WhiteListRoundRobinPolicy(self.seeds),
                                    request_timeout=self.START_TIMEOUT)
         with Cluster(execution_profiles={EXEC_PROFILE_DEFAULT: profile},
-                     contact_points=[self.seed],
+                     contact_points=self.seeds,
                      auth_provider=auth,
                      # This is the latest version Scylla supports
                      protocol_version=4,
@@ -419,14 +419,13 @@ Check the log files:
 
 class ScyllaCluster:
     def __init__(self, replicas: int,
-                 create_server: Callable[[str, Optional[str]], ScyllaServer]) -> None:
+                 create_server: Callable[[str, Optional[List[str]]], ScyllaServer]) -> None:
         self.name = str(uuid.uuid1())
         self.replicas = replicas
         self.cluster: List[ScyllaServer] = []
         self.create_server = create_server
         self.start_exception: Optional[Exception] = None
         self.keyspace_count = 0
-        self.last_seed: Optional[str] = None     # id as IP Address like '127.1.2.3'
 
     async def install_and_start(self) -> None:
         try:
@@ -439,9 +438,12 @@ class ScyllaCluster:
             self.start_exception = e
         logging.info("Created cluster %s", self)
 
+    def _seeds(self) -> List[str]:
+        return [server.host for server in self.cluster]
+
     async def add_server(self) -> None:
         """Add a new server to the cluster"""
-        server = self.create_server(self.name, self.last_seed)
+        server = self.create_server(self.name, self._seeds())
         self.cluster.append(server)
         try:
             await server.install_and_start()
@@ -449,7 +451,6 @@ class ScyllaCluster:
             logging.error("Failed to start Scylla server at host %s in %s: %s",
                           server.hostname, server.workdir.name, str(e))
             raise
-        self.last_seed = server.host
 
     def __getitem__(self, i: int) -> ScyllaServer:
         return self.cluster[i]