diff --git a/swh/core/db/db_utils.py b/swh/core/db/db_utils.py
--- a/swh/core/db/db_utils.py
+++ b/swh/core/db/db_utils.py
@@ -689,3 +689,12 @@
             "Asked for flavor %s, but module does not support database flavors",
             flavor,
         )
+
+    # Grant read-access to guest user on all tables of the schema (if possible)
+    with connect_to_conninfo(db_or_conninfo) as db:
+        try:
+            with db.cursor() as c:
+                query = "grant select on all tables in schema public to guest"
+                c.execute(query)
+        except Exception:
+            logger.warning("Grant read-only access to guest user failed. Skipping.")
diff --git a/swh/core/db/tests/conftest.py b/swh/core/db/tests/conftest.py
--- a/swh/core/db/tests/conftest.py
+++ b/swh/core/db/tests/conftest.py
@@ -7,7 +7,9 @@
 
 from click.testing import CliRunner
 from hypothesis import HealthCheck
+import psycopg2
 import pytest
+from pytest_postgresql import factories
 
 from swh.core.db.db_utils import import_swhmodule
 
@@ -21,6 +23,17 @@
 )
 
 
+def create_role_guest(**kwargs):
+    with psycopg2.connect(**kwargs) as conn:
+        with conn.cursor() as cur:
+            cur.execute("CREATE ROLE guest LOGIN PASSWORD 'guest'")
+
+
+postgresql_proc = factories.postgresql_proc(
+    load=[create_role_guest],
+)
+
+
 @pytest.fixture
 def cli_runner():
     return CliRunner()