webapp: handle read-only database

webapp/database.py

@@ -116,6 +116,15 @@ async def connect(self):
         await self.con.execute("PRAGMA synchronous=normal")
         await self.init_database_structure()
 
+    async def is_readonly(self) -> bool:
+        assert self.con is not None, "database connection closed"
+        try:
+            # This statement has no effects on a writable database
+            await self.con.execute("pragma user_version=0")
+            return False
+        except aiosqlite.OperationalError:
+            return True
+
     async def close(self):
         assert self.con is not None, "database connection closed"
         await self.con.close()

webapp/main.py

@@ -254,10 +254,14 @@ async def lifespan(app):
     Close database on exit.
     """
     await database.connect()
-    await database.update_ctf_config(CTF_CONFIG)
-    db_task = asyncio.create_task(database.importer_task())
-    yield
-    db_task.cancel()
+    if await database.is_readonly():
+        print("SQLite database opened in read-only mode", flush=True)
+        yield
+    else:
+        await database.update_ctf_config(CTF_CONFIG)
+        db_task = asyncio.create_task(database.importer_task())
+        yield
+        db_task.cancel()
     await database.close()