adam-christian-software commented on code in PR #39: URL: https://github.com/apache/polaris-tools/pull/39#discussion_r2524545289
########## mcp-server/polaris_mcp/server.py: ########## @@ -0,0 +1,439 @@ +# +# Licensed to the Apache Software Foundation (ASF) under one +# or more contributor license agreements. See the NOTICE file +# distributed with this work for additional information +# regarding copyright ownership. The ASF licenses this file +# to you under the Apache License, Version 2.0 (the +# "License"); you may not use this file except in compliance +# with the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, +# software distributed under the License is distributed on an +# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +# KIND, either express or implied. See the License for the +# specific language governing permissions and limitations +# under the License. +# + +"""Entry point for the Polaris Model Context Protocol server.""" + +from __future__ import annotations + +import os +from typing import Any, Mapping, MutableMapping, Sequence +from urllib.parse import urljoin + +import urllib3 +from fastmcp import FastMCP +from fastmcp.tools.tool import ToolResult as FastMcpToolResult +from importlib import metadata +from mcp.types import TextContent + +from .authorization import ( + AuthorizationProvider, + ClientCredentialsAuthorizationProvider, + StaticAuthorizationProvider, + none, +) +from .base import ToolExecutionResult +from .tools import ( + PolarisCatalogRoleTool, + PolarisCatalogTool, + PolarisNamespaceTool, + PolarisPolicyTool, + PolarisPrincipalRoleTool, + PolarisPrincipalTool, + PolarisTableTool, +) + +DEFAULT_BASE_URL = "http://localhost:8181/"; +OUTPUT_SCHEMA = { + "type": "object", + "properties": { + "isError": {"type": "boolean"}, + "meta": {"type": "object"}, + }, + "required": ["isError"], + "additionalProperties": True, +} + + +def create_server() -> FastMCP: + """Construct a FastMCP server with Polaris tools.""" + + base_url = _resolve_base_url() + http = urllib3.PoolManager() + authorization_provider = _resolve_authorization_provider(base_url, http) + + table_tool = PolarisTableTool(base_url, http, authorization_provider) + namespace_tool = PolarisNamespaceTool(base_url, http, authorization_provider) + principal_tool = PolarisPrincipalTool(base_url, http, authorization_provider) + principal_role_tool = PolarisPrincipalRoleTool(base_url, http, authorization_provider) + catalog_role_tool = PolarisCatalogRoleTool(base_url, http, authorization_provider) + policy_tool = PolarisPolicyTool(base_url, http, authorization_provider) + catalog_tool = PolarisCatalogTool(base_url, http, authorization_provider) + + server_version = _resolve_package_version() + mcp = FastMCP( + name="polaris-mcp", + version=server_version, + ) + + @mcp.tool( + name=table_tool.name, + description=table_tool.description, + output_schema=OUTPUT_SCHEMA, + ) + def polaris_iceberg_table( + operation: str, + catalog: str, + namespace: str | Sequence[str], + table: str | None = None, + query: Mapping[str, str | Sequence[str]] | None = None, + headers: Mapping[str, str | Sequence[str]] | None = None, + body: Any | None = None, + ) -> FastMcpToolResult: + return _call_tool( + table_tool, + required={ + "operation": operation, + "catalog": catalog, + "namespace": namespace, + }, + optional={ + "table": table, + "query": query, + "headers": headers, + "body": body, + }, + transforms={ + "namespace": _normalize_namespace, + "query": _copy_mapping, + "headers": _copy_mapping, + "body": _coerce_body, + }, + ) + + @mcp.tool( + name=namespace_tool.name, + description=namespace_tool.description, + output_schema=OUTPUT_SCHEMA, + ) + def polaris_namespace_request( + operation: str, + catalog: str, + namespace: str | Sequence[str] | None = None, + query: Mapping[str, str | Sequence[str]] | None = None, + headers: Mapping[str, str | Sequence[str]] | None = None, + body: Any | None = None, + ) -> FastMcpToolResult: + return _call_tool( + namespace_tool, + required={ + "operation": operation, + "catalog": catalog, + }, + optional={ + "namespace": namespace, + "query": query, + "headers": headers, + "body": body, + }, + transforms={ + "namespace": _normalize_namespace, + "query": _copy_mapping, + "headers": _copy_mapping, + "body": _coerce_body, + }, + ) + + @mcp.tool( + name=principal_tool.name, + description=principal_tool.description, + output_schema=OUTPUT_SCHEMA, + ) + def polaris_principal_request( + operation: str, + principal: str | None = None, + principalRole: str | None = None, + query: Mapping[str, str | Sequence[str]] | None = None, + headers: Mapping[str, str | Sequence[str]] | None = None, + body: Any | None = None, + ) -> FastMcpToolResult: + return _call_tool( + principal_tool, + required={"operation": operation}, + optional={ + "principal": principal, + "principalRole": principalRole, + "query": query, + "headers": headers, + "body": body, + }, + transforms={ + "query": _copy_mapping, + "headers": _copy_mapping, + "body": _coerce_body, + }, + ) + + @mcp.tool( + name=principal_role_tool.name, + description=principal_role_tool.description, + output_schema=OUTPUT_SCHEMA, + ) + def polaris_principal_role_request( + operation: str, + principalRole: str | None = None, + catalog: str | None = None, + catalogRole: str | None = None, + query: Mapping[str, str | Sequence[str]] | None = None, + headers: Mapping[str, str | Sequence[str]] | None = None, + body: Any | None = None, + ) -> FastMcpToolResult: + return _call_tool( + principal_role_tool, + required={"operation": operation}, + optional={ + "principalRole": principalRole, + "catalog": catalog, + "catalogRole": catalogRole, + "query": query, + "headers": headers, + "body": body, + }, + transforms={ + "query": _copy_mapping, + "headers": _copy_mapping, + "body": _coerce_body, + }, + ) + + @mcp.tool( + name=catalog_role_tool.name, + description=catalog_role_tool.description, + output_schema=OUTPUT_SCHEMA, + ) + def polaris_catalog_role_request( + operation: str, + catalog: str, + catalogRole: str | None = None, + query: Mapping[str, str | Sequence[str]] | None = None, + headers: Mapping[str, str | Sequence[str]] | None = None, + body: Any | None = None, + ) -> FastMcpToolResult: + return _call_tool( + catalog_role_tool, + required={ + "operation": operation, + "catalog": catalog, + }, + optional={ + "catalogRole": catalogRole, + "query": query, + "headers": headers, + "body": body, + }, + transforms={ + "query": _copy_mapping, + "headers": _copy_mapping, + "body": _coerce_body, + }, + ) + + @mcp.tool( + name=policy_tool.name, + description=policy_tool.description, + output_schema=OUTPUT_SCHEMA, + ) + def polaris_policy_request( + operation: str, + catalog: str, + namespace: str | Sequence[str] | None = None, + policy: str | None = None, + query: Mapping[str, str | Sequence[str]] | None = None, + headers: Mapping[str, str | Sequence[str]] | None = None, + body: Any | None = None, + ) -> FastMcpToolResult: + return _call_tool( + policy_tool, + required={ + "operation": operation, + "catalog": catalog, + }, + optional={ + "namespace": namespace, + "policy": policy, + "query": query, + "headers": headers, + "body": body, + }, + transforms={ + "namespace": _normalize_namespace, + "query": _copy_mapping, + "headers": _copy_mapping, + "body": _coerce_body, + }, + ) + + @mcp.tool( + name=catalog_tool.name, + description=catalog_tool.description, + output_schema=OUTPUT_SCHEMA, + ) + def polaris_catalog_request( + operation: str, + catalog: str | None = None, + query: Mapping[str, str | Sequence[str]] | None = None, + headers: Mapping[str, str | Sequence[str]] | None = None, + body: Any | None = None, + ) -> FastMcpToolResult: + return _call_tool( + catalog_tool, + required={"operation": operation}, + optional={ + "catalog": catalog, + "query": query, + "headers": headers, + "body": body, + }, + transforms={ + "query": _copy_mapping, + "headers": _copy_mapping, + "body": _coerce_body, + }, + ) + + return mcp + + +def _call_tool( + tool: Any, + *, + required: Mapping[str, Any], + optional: Mapping[str, Any | None] | None = None, + transforms: Mapping[str, Any] | None = None, +) -> FastMcpToolResult: + arguments: MutableMapping[str, Any] = dict(required) + if optional: + for key, value in optional.items(): + if value is not None: + arguments[key] = value + if transforms: + for key, transform in transforms.items(): + if key in arguments and arguments[key] is not None: + arguments[key] = transform(arguments[key]) + return _to_tool_result(tool.call(arguments)) + + +def _to_tool_result(result: ToolExecutionResult) -> FastMcpToolResult: + structured = {"isError": result.is_error} + if result.metadata is not None: + structured["meta"] = result.metadata + return FastMcpToolResult( + content=[TextContent(type="text", text=result.text)], + structured_content=structured, + ) + + +def _copy_mapping( + mapping: Mapping[str, Any] | None, +) -> MutableMapping[str, Any] | None: + if mapping is None: + return None + copied: MutableMapping[str, Any] = {} + for key, value in mapping.items(): + if value is None: + continue + if isinstance(value, (list, tuple)): + copied[key] = [str(item) for item in value] + else: + copied[key] = value + return copied + + +def _coerce_body(body: Any) -> Any: + """Return plain dicts for mapping objects so downstream JSON encoding succeeds.""" + if isinstance(body, Mapping): + return dict(body) + return body + + +def _normalize_namespace(namespace: str | Sequence[str]) -> str | list[str]: + if isinstance(namespace, str): + return namespace + return [str(part) for part in namespace] + + +def _resolve_base_url() -> str: + for candidate in ( + os.getenv("POLARIS_BASE_URL"), + os.getenv("POLARIS_REST_BASE_URL"), + ): + if candidate and candidate.strip(): Review Comment: Looks good to me! -- This is an automated message from the Apache Git Service. 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