add postgres kvstoreimpl (#374)

* add postgres kvstoreimpl

* make table name configurable

* add validator for table name

* linter fix

---------

Co-authored-by: Dinesh Yeduguru <dineshyv@fb.com>

llama_stack/providers/utils/kvstore/config.py

@@ -4,10 +4,11 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
+import re
 from enum import Enum
 from typing import Literal, Optional, Union
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 from typing_extensions import Annotated
 
 from llama_stack.distribution.utils.config_dirs import RUNTIME_BASE_DIR
@@ -51,6 +52,22 @@ class PostgresKVStoreConfig(CommonConfig):
     db: str = "llamastack"
     user: str
     password: Optional[str] = None
+    table_name: str = "llamastack_kvstore"
+
+    @field_validator("table_name")
+    def validate_table_name(self, v: str) -> str:
+        # PostgreSQL identifiers rules:
+        # - Must start with a letter or underscore
+        # - Can contain letters, numbers, and underscores
+        # - Maximum length is 63 bytes
+        pattern = r"^[a-zA-Z_][a-zA-Z0-9_]*$"
+        if not re.match(pattern, v):
+            raise ValueError(
+                "Invalid table name. Must start with letter or underscore and contain only letters, numbers, and underscores"
+            )
+        if len(v) > 63:
+            raise ValueError("Table name must be less than 63 characters")
+        return v
 
 
 KVStoreConfig = Annotated[