fix: update README and introspection logic to support schema files hosted at URLs (#32)

Author: umidjon-2231

README.md

@@ -20,7 +20,7 @@ Run `mcp-graphql` with the correct endpoint, it will automatically try to intros
 | `HEADERS` | JSON string containing headers for requests | `{}` |
 | `ALLOW_MUTATIONS` | Enable mutation operations (disabled by default) | `false` |
 | `NAME` | Name of the MCP server | `mcp-graphql` |
-| `SCHEMA` | Path to a local GraphQL schema file (optional) | - |
+| `SCHEMA` | Path to a local GraphQL schema file or URL (optional) | - |
 
 ### Examples
 
@@ -36,18 +36,21 @@ ENDPOINT=http://localhost:3000/graphql ALLOW_MUTATIONS=true npx mcp-graphql
 
 # Using a local schema file instead of introspection
 ENDPOINT=http://localhost:3000/graphql SCHEMA=./schema.graphql npx mcp-graphql
+
+# Using a schema file hosted at a URL
+ENDPOINT=http://localhost:3000/graphql SCHEMA=https://example.com/schema.graphql npx mcp-graphql
 ```
 
 ## Resources
 
-- **graphql-schema**: The server exposes the GraphQL schema as a resource that clients can access. This is either the local schema file or based on an introspection query.
+- **graphql-schema**: The server exposes the GraphQL schema as a resource that clients can access. This is either the local schema file, a schema file hosted at a URL, or based on an introspection query.
 
 ## Available Tools
 
 The server provides two main tools:
 
 1. **introspect-schema**: This tool retrieves the GraphQL schema. Use this first if you don't have access to the schema as a resource.
-This uses either the local schema file or an introspection query.
+This uses either the local schema file, a schema file hosted at a URL, or an introspection query.
 
 2. **query-graphql**: Execute GraphQL queries against the endpoint. By default, mutations are disabled unless `ALLOW_MUTATIONS` is set to `true`.
 

src/helpers/introspection.ts

@@ -1,35 +1,53 @@
-import { buildClientSchema, getIntrospectionQuery, printSchema } from "graphql";
-import { readFile } from "node:fs/promises";
+import {buildClientSchema, getIntrospectionQuery, printSchema} from "graphql";
+import {readFile} from "node:fs/promises";
+
 /**
  * Introspect a GraphQL endpoint and return the schema as the GraphQL SDL
  * @param endpoint - The endpoint to introspect
+ * @param headers - Optional headers to include in the request
  * @returns The schema
  */
 export async function introspectEndpoint(
-	endpoint: string,
-	headers?: Record<string, string>,
+    endpoint: string,
+    headers?: Record<string, string>,
 ) {
-	const response = await fetch(endpoint, {
-		method: "POST",
-		headers: {
-			"Content-Type": "application/json",
-			...headers,
-		},
-		body: JSON.stringify({
-			query: getIntrospectionQuery(),
-		}),
-	});
-
-	if (!response.ok) {
-		throw new Error(`GraphQL request failed: ${response.statusText}`);
-	}
-
-	const responseJson = await response.json();
-	// Transform to a schema object
-	const schema = buildClientSchema(responseJson.data);
-
-	// Print the schema SDL
-	return printSchema(schema);
+    const response = await fetch(endpoint, {
+        method: "POST",
+        headers: {
+            "Content-Type": "application/json",
+            ...headers,
+        },
+        body: JSON.stringify({
+            query: getIntrospectionQuery(),
+        }),
+    });
+
+    if (!response.ok) {
+        throw new Error(`GraphQL request failed: ${response.statusText}`);
+    }
+
+    const responseJson = await response.json();
+    // Transform to a schema object
+    const schema = buildClientSchema(responseJson.data);
+
+    // Print the schema SDL
+    return printSchema(schema);
+}
+
+/**
+ * Introspect a GraphQL schema file hosted at a URL and return the schema as the GraphQL SDL
+ * @param url - The URL to the schema file
+ * @returns The schema
+ */
+export async function introspectSchemaFromUrl(url: string) {
+    const response = await fetch(url);
+
+    if (!response.ok) {
+        throw new Error(`Failed to fetch schema from URL: ${response.statusText}`);
+    }
+
+    const schema = await response.text();
+    return schema;
 }
 
 /**
@@ -38,6 +56,6 @@ export async function introspectEndpoint(
  * @returns The schema
  */
 export async function introspectLocalSchema(path: string) {
-	const schema = await readFile(path, "utf8");
-	return schema;
+    const schema = await readFile(path, "utf8");
+    return schema;
 }