Allow enabling S3 mock in all existing tests with an env var

test_runner/README.md

@@ -48,6 +48,7 @@ Useful environment variables:
 should go.
 `TEST_SHARED_FIXTURES`: Try to re-use a single pageserver for all the tests.
 `ZENITH_PAGESERVER_OVERRIDES`: add a `;`-separated set of configs that will be passed as
+`FORCE_MOCK_S3`: inits every test's pageserver with a mock S3 used as a remote storage.
 `--pageserver-config-override=${value}` parameter values when zenith cli is invoked
 `RUST_LOG`: logging configuration to pass into Zenith CLI
 

test_runner/fixtures/zenith_fixtures.py

@@ -395,9 +395,15 @@ class ZenithEnvBuilder:
         self.pageserver_remote_storage = pageserver_remote_storage
         self.num_safekeepers = num_safekeepers
         self.pageserver_auth_enabled = pageserver_auth_enabled
-        self.s3_mock_server: Optional[MockS3Server] = None
         self.env: Optional[ZenithEnv] = None
 
+        self.s3_mock_server: Optional[MockS3Server] = None
+
+        if os.getenv('FORCE_MOCK_S3') is not None:
+            bucket_name = f'{repo_dir.name}_bucket'
+            log.warning(f'Unconditionally initializing mock S3 server for bucket {bucket_name}')
+            self.enable_s3_mock_remote_storage(bucket_name)
+
     def init(self) -> ZenithEnv:
         # Cannot create more than one environment from one builder
         assert self.env is None, "environment already initialized"