From ee7c8a4662768dd0bc24d7912ce4b881f1184a86 Mon Sep 17 00:00:00 2001
From: Antonio Goncalves <antonio.goncalves@gmail.com>
Date: Tue, 18 Feb 2025 08:44:43 +0100
Subject: [PATCH] Adds a GitHub MCP Server sample (#141)

@dliubarskyi once this sample is merge I will write about it in the
LangChain4j documentation

See https://github.com/langchain4j/langchain4j/pull/2512

---------

Co-authored-by: Julien Dubois <julien.dubois@gmail.com>
---
 mcp-github-example/pom.xml                    | 51 ++++++++++++++
 .../langchain4j/example/mcp/github/Bot.java   |  6 ++
 .../mcp/github/McpGithubToolsExample.java     | 66 +++++++++++++++++++
 .../src/main/resources/logback.xml            | 12 ++++
 pom.xml                                       |  1 +
 5 files changed, 136 insertions(+)
 create mode 100644 mcp-github-example/pom.xml
 create mode 100644 mcp-github-example/src/main/java/dev/langchain4j/example/mcp/github/Bot.java
 create mode 100644 mcp-github-example/src/main/java/dev/langchain4j/example/mcp/github/McpGithubToolsExample.java
 create mode 100644 mcp-github-example/src/main/resources/logback.xml

diff --git a/mcp-github-example/pom.xml b/mcp-github-example/pom.xml
new file mode 100644
index 0000000..d487aa3
--- /dev/null
+++ b/mcp-github-example/pom.xml
@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>dev.langchain4j</groupId>
+    <artifactId>mcp-github-example</artifactId>
+    <version>1.0.0-beta1</version>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <dependencies>
+
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-mcp</artifactId>
+            <version>1.0.0-beta1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-open-ai</artifactId>
+            <version>1.0.0-beta1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>5.10.0</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.25.3</version>
+        </dependency>
+
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+            <version>1.5.16</version>
+        </dependency>
+
+    </dependencies>
+
+</project>
diff --git a/mcp-github-example/src/main/java/dev/langchain4j/example/mcp/github/Bot.java b/mcp-github-example/src/main/java/dev/langchain4j/example/mcp/github/Bot.java
new file mode 100644
index 0000000..8f317bf
--- /dev/null
+++ b/mcp-github-example/src/main/java/dev/langchain4j/example/mcp/github/Bot.java
@@ -0,0 +1,6 @@
+package dev.langchain4j.example.mcp.github;
+
+public interface Bot {
+
+    String chat(String prompt);
+}
diff --git a/mcp-github-example/src/main/java/dev/langchain4j/example/mcp/github/McpGithubToolsExample.java b/mcp-github-example/src/main/java/dev/langchain4j/example/mcp/github/McpGithubToolsExample.java
new file mode 100644
index 0000000..406db07
--- /dev/null
+++ b/mcp-github-example/src/main/java/dev/langchain4j/example/mcp/github/McpGithubToolsExample.java
@@ -0,0 +1,66 @@
+package dev.langchain4j.example.mcp.github;
+
+import dev.langchain4j.mcp.McpToolProvider;
+import dev.langchain4j.mcp.client.DefaultMcpClient;
+import dev.langchain4j.mcp.client.McpClient;
+import dev.langchain4j.mcp.client.transport.McpTransport;
+import dev.langchain4j.mcp.client.transport.stdio.StdioMcpTransport;
+import dev.langchain4j.model.chat.ChatLanguageModel;
+import dev.langchain4j.model.openai.OpenAiChatModel;
+import dev.langchain4j.service.AiServices;
+import dev.langchain4j.service.tool.ToolProvider;
+
+import java.util.List;
+
+public class McpGithubToolsExample {
+
+    /**
+     * This example uses the GitHub MCP server to showcase how
+     * to use an LLM to summarize the last commits of a public GitHub repo.
+     * Being a public repository (the LangChain4j repository is used as an example), you don't need any
+     * authentication to access the data.
+     * <p>
+     * Running this example requires Docker to be installed on your machine,
+     * because it spawns the GitHub MCP Server as a subprocess via Docker:
+     * `docker run -i mcp/github`.
+     * <p>
+     * You first need to build the Docker image of the GitHub MCP Server that is available at `mcp/github`.
+     * See https://github.com/modelcontextprotocol/servers/tree/main/src/github to build the image.
+     * <p>
+     * The communication with the GitHub MCP server is done directly via stdin/stdout.
+     */
+    public static void main(String[] args) throws Exception {
+
+        ChatLanguageModel model = OpenAiChatModel.builder()
+                .apiKey(System.getenv("OPENAI_API_KEY"))
+                .modelName("gpt-4o-mini")
+                .logRequests(true)
+                .logResponses(true)
+                .build();
+
+        McpTransport transport = new StdioMcpTransport.Builder()
+                .command(List.of("/usr/local/bin/docker", "run", "-e", "GITHUB_PERSONAL_ACCESS_TOKEN", "-i", "mcp/github"))
+                .logEvents(true)
+                .build();
+
+        McpClient mcpClient = new DefaultMcpClient.Builder()
+                .transport(transport)
+                .build();
+
+        ToolProvider toolProvider = McpToolProvider.builder()
+                .mcpClients(List.of(mcpClient))
+                .build();
+
+        Bot bot = AiServices.builder(Bot.class)
+                .chatLanguageModel(model)
+                .toolProvider(toolProvider)
+                .build();
+
+        try {
+            String response = bot.chat("Summarize the last 3 commits of the LangChain4j GitHub repository");
+            System.out.println("RESPONSE: " + response);
+        } finally {
+            mcpClient.close();
+        }
+    }
+}
diff --git a/mcp-github-example/src/main/resources/logback.xml b/mcp-github-example/src/main/resources/logback.xml
new file mode 100644
index 0000000..8a7c97e
--- /dev/null
+++ b/mcp-github-example/src/main/resources/logback.xml
@@ -0,0 +1,12 @@
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%-5level %logger{36} - %msg%n</pattern>
+        </encoder>
+    </appender>
+
+    <!--  Set the level to `debug` to see more detailed logs.-->
+    <root level="info">
+        <appender-ref ref="STDOUT"/>
+    </root>
+</configuration>
diff --git a/pom.xml b/pom.xml
index 5a74f31..00eb8a3 100644
--- a/pom.xml
+++ b/pom.xml
@@ -24,6 +24,7 @@
         <module>jakartaee-microprofile-example</module>
         <module>jlama-examples</module>
         <module>mcp-example</module>
+        <module>mcp-github-example</module>
         <module>milvus-example</module>
         <module>mistral-ai-examples</module>
         <module>neo4j-example</module>