tests: improve coverage of pageserver restarts

test_runner/fixtures/pageserver/http.py

@@ -302,6 +302,15 @@ class PageserverHttpClient(requests.Session):
         )
         self.verbose_error(res)
 
+    def tenant_list_locations(self):
+        res = self.get(
+            f"http://localhost:{self.port}/v1/location_config",
+        )
+        self.verbose_error(res)
+        res_json = res.json()
+        assert isinstance(res_json["tenant_shards"], list)
+        return res_json
+
     def tenant_delete(self, tenant_id: Union[TenantId, TenantShardId]):
         res = self.delete(f"http://localhost:{self.port}/v1/tenant/{tenant_id}")
         self.verbose_error(res)

test_runner/regress/test_sharding.py

@@ -213,11 +213,6 @@ def test_sharding_split_smoke(
     all_shards = tenant_get_shards(env, tenant_id)
     for tenant_shard_id, pageserver in all_shards:
         pageserver.http_client().timeline_gc(tenant_shard_id, timeline_id, None)
-
-    # Restart all nodes, to check that the newly created shards are durable
-    for ps in env.pageservers:
-        ps.restart()
-
     workload.validate()
 
     migrate_to_pageserver_ids = list(
@@ -240,3 +235,27 @@ def test_sharding_split_smoke(
         env.neon_cli.tenant_migrate(migrate_shard, destination, timeout_secs=10)
 
     workload.validate()
+
+    # Validate pageserver state
+    shards_exist: list[TenantShardId] = []
+    for pageserver in env.pageservers:
+        locations = pageserver.http_client().tenant_list_locations()
+        shards_exist.extend(TenantShardId.parse(s[0]) for s in locations["tenant_shards"])
+
+    log.info("Shards after split: {shards_exist}")
+    assert len(shards_exist) == split_shard_count
+
+    # Ensure post-split pageserver locations survive a restart (i.e. the child shards
+    # correctly wrote config to disk, and the storage controller responds correctly
+    # to /re-attach)
+    for pageserver in env.pageservers:
+        pageserver.stop()
+        pageserver.start()
+
+    shards_exist = []
+    for pageserver in env.pageservers:
+        locations = pageserver.http_client().tenant_list_locations()
+        shards_exist.extend(TenantShardId.parse(s[0]) for s in locations["tenant_shards"])
+
+    log.info("Shards after restart: {shards_exist}")
+    assert len(shards_exist) == split_shard_count

test_runner/regress/test_sharding_service.py

@@ -108,6 +108,20 @@ def test_sharding_service_smoke(
     time.sleep(1)
     assert get_node_shard_counts(env, tenant_ids)[env.pageservers[0].id] == 0
 
+    # Restarting a pageserver should not detach any tenants (i.e. /re-attach works)
+    before_restart = env.pageservers[1].http_client().tenant_list_locations()
+    env.pageservers[1].stop()
+    env.pageservers[1].start()
+    after_restart = env.pageservers[1].http_client().tenant_list_locations()
+    assert len(after_restart) == len(before_restart)
+
+    # Locations should be the same before & after restart, apart from generations
+    for _shard_id, tenant in after_restart["tenant_shards"]:
+        del tenant["generation"]
+    for _shard_id, tenant in before_restart["tenant_shards"]:
+        del tenant["generation"]
+    assert before_restart == after_restart
+
     # Delete all the tenants
     for tid in tenant_ids:
         tenant_delete_wait_completed(env.attachment_service.pageserver_api(), tid, 10)