add support for SSE

Author: light4

README.md

@@ -70,6 +70,7 @@ The Elasticsearch MCP Server supports configuration options to connect to your E
 
 | Environment Variable | Description | Required |
 |---------------------|-------------|----------|
+| `SSE_ADDR` | Enable SSE and set the ADDR | No |
 | `ES_URL` | Your Elasticsearch instance URL | Yes |
 | `ES_API_KEY` | Elasticsearch API key for authentication | No |
 | `ES_USERNAME` | Elasticsearch username for basic authentication | No |

index.ts

@@ -5,15 +5,24 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import express, { Request, Response } from "express";
+import morgan from "morgan";
 import { z } from "zod";
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
-import { Client, estypes, ClientOptions } from "@elastic/elasticsearch";
+import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
+import { Client, ClientOptions, estypes } from "@elastic/elasticsearch";
 import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
 import fs from "fs";
 
 // Configuration schema with auth options
 const ConfigSchema = z
   .object({
+    sse_addr: z
+      .string()
+      .trim()
+      .optional()
+      .describe("Address for SSE server (optional)"),
+
     url: z
       .string()
       .trim()
@@ -65,13 +74,13 @@ const ConfigSchema = z
       message:
         "Either ES_API_KEY or both ES_USERNAME and ES_PASSWORD must be provided, or no auth for local development",
       path: ["username", "password"],
-    }
+    },
   );
 
 type ElasticsearchConfig = z.infer<typeof ConfigSchema>;
 
 export async function createElasticsearchMcpServer(
-  config: ElasticsearchConfig
+  config: ElasticsearchConfig,
 ) {
   const validatedConfig = ConfigSchema.parse(config);
   const { url, apiKey, username, password, caCert } = validatedConfig;
@@ -96,7 +105,7 @@ export async function createElasticsearchMcpServer(
       console.error(
         `Failed to read certificate file: ${
           error instanceof Error ? error.message : String(error)
-        }`
+        }`,
       );
     }
   }
@@ -140,7 +149,7 @@ export async function createElasticsearchMcpServer(
         console.error(
           `Failed to list indices: ${
             error instanceof Error ? error.message : String(error)
-          }`
+          }`,
         );
         return {
           content: [
@@ -153,7 +162,7 @@ export async function createElasticsearchMcpServer(
           ],
         };
       }
-    }
+    },
   );
 
   // Tool 2: Get mappings for an index
@@ -181,19 +190,21 @@ export async function createElasticsearchMcpServer(
             },
             {
               type: "text" as const,
-              text: `Mappings for index ${index}: ${JSON.stringify(
-                mappingResponse[index]?.mappings || {},
-                null,
-                2
-              )}`,
+              text: `Mappings for index ${index}: ${
+                JSON.stringify(
+                  mappingResponse[index]?.mappings || {},
+                  null,
+                  2,
+                )
+              }`,
             },
           ],
         };
       } catch (error) {
         console.error(
           `Failed to get mappings: ${
             error instanceof Error ? error.message : String(error)
-          }`
+          }`,
         );
         return {
           content: [
@@ -206,7 +217,7 @@ export async function createElasticsearchMcpServer(
           ],
         };
       }
-    }
+    },
   );
 
   // Tool 3: Search an index with simplified parameters
@@ -233,10 +244,10 @@ export async function createElasticsearchMcpServer(
           },
           {
             message: "queryBody must be a valid Elasticsearch query DSL object",
-          }
+          },
         )
         .describe(
-          "Complete Elasticsearch query DSL object that can include query, size, from, sort, etc."
+          "Complete Elasticsearch query DSL object that can include query, size, from, sort, etc.",
         ),
     },
     async ({ index, queryBody }) => {
@@ -257,9 +268,11 @@ export async function createElasticsearchMcpServer(
         if (indexMappings.properties) {
           const textFields: Record<string, estypes.SearchHighlightField> = {};
 
-          for (const [fieldName, fieldData] of Object.entries(
-            indexMappings.properties
-          )) {
+          for (
+            const [fieldName, fieldData] of Object.entries(
+              indexMappings.properties,
+            )
+          ) {
             if (fieldData.type === "text" || "dense_vector" in fieldData) {
               textFields[fieldName] = {};
             }
@@ -285,9 +298,11 @@ export async function createElasticsearchMcpServer(
 
           for (const [field, highlights] of Object.entries(highlightedFields)) {
             if (highlights && highlights.length > 0) {
-              content += `${field} (highlighted): ${highlights.join(
-                " ... "
-              )}\n`;
+              content += `${field} (highlighted): ${
+                highlights.join(
+                  " ... ",
+                )
+              }\n`;
             }
           }
 
@@ -319,7 +334,7 @@ export async function createElasticsearchMcpServer(
         console.error(
           `Search failed: ${
             error instanceof Error ? error.message : String(error)
-          }`
+          }`,
         );
         return {
           content: [
@@ -332,7 +347,7 @@ export async function createElasticsearchMcpServer(
           ],
         };
       }
-    }
+    },
   );
 
   // Tool 4: Get shard information
@@ -383,7 +398,7 @@ export async function createElasticsearchMcpServer(
         console.error(
           `Failed to get shard information: ${
             error instanceof Error ? error.message : String(error)
-          }`
+          }`,
         );
         return {
           content: [
@@ -396,36 +411,81 @@ export async function createElasticsearchMcpServer(
           ],
         };
       }
-    }
+    },
   );
 
   return server;
 }
 
 const config: ElasticsearchConfig = {
+  sse_addr: process.env.SSE_ADDR || "",
   url: process.env.ES_URL || "",
   apiKey: process.env.ES_API_KEY || "",
   username: process.env.ES_USERNAME || "",
   password: process.env.ES_PASSWORD || "",
   caCert: process.env.ES_CA_CERT || "",
 };
 
+async function create_sse_server(server: any) {
+  const app = express();
+
+  // Use morgan to log every request
+  app.use(morgan("combined"));
+
+  const transports: { [sessionId: string]: SSEServerTransport } = {};
+
+  app.get("/sse", async (_: Request, res: Response) => {
+    const transport = new SSEServerTransport("/messages", res);
+    transports[transport.sessionId] = transport;
+    res.on("close", () => {
+      delete transports[transport.sessionId];
+    });
+    await server.connect(transport);
+  });
+
+  app.post("/messages", async (req: Request, res: Response) => {
+    const sessionId = req.query.sessionId as string;
+    const transport = transports[sessionId];
+    if (transport) {
+      await transport.handlePostMessage(req, res);
+    } else {
+      res.status(400).send("No transport found for sessionId");
+    }
+  });
+
+  const sseAddr = process.env.SSE_ADDR || "127.0.0.1:3000";
+  const [host, port] = sseAddr.split(":");
+  if (!port) {
+    console.error("Invalid SSE_ADDR format. Expected 'host:port'.");
+    process.exit(1);
+  }
+
+  app.listen(Number(port), host, () => {
+    console.info(`SSE server started on: ${host}:${port}`);
+  });
+}
+
 async function main() {
-  const transport = new StdioServerTransport();
+  console.info("Starting Elasticsearch MCP server...");
   const server = await createElasticsearchMcpServer(config);
 
-  await server.connect(transport);
+  if (process.env.SSE_ADDR) {
+    await create_sse_server(server);
+  } else {
+    const transport = new StdioServerTransport();
+    await server.connect(transport);
 
-  process.on("SIGINT", async () => {
-    await server.close();
-    process.exit(0);
-  });
+    process.on("SIGINT", async () => {
+      await server.close();
+      process.exit(0);
+    });
+  }
 }
 
 main().catch((error) => {
   console.error(
     "Server error:",
-    error instanceof Error ? error.message : String(error)
+    error instanceof Error ? error.message : String(error),
   );
   process.exit(1);
 });

package.json

@@ -38,7 +38,11 @@
   },
   "dependencies": {
     "@elastic/elasticsearch": "^8.17.1",
-    "@modelcontextprotocol/sdk": "1.9.0"
+    "@modelcontextprotocol/sdk": "1.9.0",
+    "@types/express": "^5.0.1",
+    "@types/morgan": "^1.9.9",
+    "express": "^5.1.0",
+    "morgan": "^1.10.0"
   },
   "engines": {
     "node": ">=18"