diff --git a/swh/vault/api/server.py b/swh/vault/api/server.py
--- a/swh/vault/api/server.py
+++ b/swh/vault/api/server.py
@@ -6,6 +6,7 @@
 import asyncio
 import collections
 import os
+from typing import Any, Dict, Optional
 
 import aiohttp.web
 
@@ -192,15 +193,14 @@
     return app
 
 
-def get_local_backend(cfg):
+def check_config(cfg: Dict[str, Any]) -> Dict[str, Any]:
     if "vault" not in cfg:
-        raise ValueError("missing '%vault' configuration")
+        raise ValueError("missing 'vault' configuration")
 
     vcfg = cfg["vault"]
     if vcfg["cls"] != "local":
         raise EnvironmentError(
-            "The vault backend can only be started with a 'local' " "configuration",
-            err=True,
+            "The vault backend can only be started with a 'local' configuration",
         )
     args = vcfg["args"]
     if "cache" not in args:
@@ -212,20 +212,22 @@
 
     for key in ("cache", "storage", "scheduler"):
         if not args.get(key):
-            raise ValueError("invalid configuration; missing %s config entry." % key)
+            raise ValueError(f"invalid configuration: missing {key} config entry.")
 
-    return get_vault("local", **args)
+    return args
 
 
-def make_app_from_configfile(config_file=None, **kwargs):
+def make_app_from_configfile(config_file: Optional[str] = None, **kwargs):
     if config_file is None:
         config_file = DEFAULT_CONFIG_PATH
     config_file = os.environ.get("SWH_CONFIG_FILENAME", config_file)
+    assert config_file is not None
     if os.path.isfile(config_file):
         cfg = config.read(config_file, DEFAULT_CONFIG)
     else:
         cfg = config.load_named_config(config_file, DEFAULT_CONFIG)
-    vault = get_local_backend(cfg)
+    kwargs = check_config(cfg)
+    vault = get_vault("local", **kwargs)
     return make_app(backend=vault, client_max_size=cfg["client_max_size"], **kwargs)
 
 
diff --git a/swh/vault/tests/test_server.py b/swh/vault/tests/test_server.py
--- a/swh/vault/tests/test_server.py
+++ b/swh/vault/tests/test_server.py
@@ -3,10 +3,12 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
+import copy
+
 import pytest
 
 from swh.core.api.serializers import msgpack_dumps, msgpack_loads
-from swh.vault.api.server import make_app
+from swh.vault.api.server import check_config, make_app
 
 
 @pytest.fixture
@@ -53,3 +55,37 @@
     content = msgpack_loads(await resp.content.read())
     assert content["exception"]["type"] == "NotFoundExc"
     assert content["exception"]["args"] == ["Batch 1 does not exist."]
+
+
+def test_check_config_missing_vault_configuration() -> None:
+    """Irrelevant configuration file path raises"""
+    with pytest.raises(ValueError, match="missing 'vault' configuration"):
+        check_config({})
+
+
+def test_check_config_not_local() -> None:
+    """Wrong configuration raises"""
+    expected_error = (
+        "The vault backend can only be started with a 'local' configuration"
+    )
+    with pytest.raises(EnvironmentError, match=expected_error):
+        check_config({"vault": {"cls": "remote"}})
+
+
+@pytest.mark.parametrize("missing_key", ["storage", "cache", "scheduler"])
+def test_check_config_missing_key(missing_key, swh_vault_config) -> None:
+    """Any other configuration than 'local' (the default) is rejected"""
+    config_ok = {"vault": {"cls": "local", "args": swh_vault_config}}
+    config_ko = copy.deepcopy(config_ok)
+    config_ko["vault"]["args"].pop(missing_key, None)
+
+    expected_error = f"invalid configuration: missing {missing_key} config entry"
+    with pytest.raises(ValueError, match=expected_error):
+        check_config(config_ko)
+
+
+@pytest.mark.parametrize("missing_key", ["storage", "cache", "scheduler"])
+def test_check_config_ok(missing_key, swh_vault_config) -> None:
+    """Any other configuration than 'local' (the default) is rejected"""
+    config_ok = {"vault": {"cls": "local", "args": swh_vault_config}}
+    assert check_config(config_ok) is not None