mcp-server-docker

Instructions

Implementation Reference

• src/docker.ts:100-122 (handler)

  Core handler function that executes a command inside a Docker container using Dockerode. Creates an exec instance, starts it, collects output chunks from the stream, and returns the combined output as a string.

  export async function execCommand(
    id: string,
    command: string[],
  ): Promise<string> {
    const container = docker.getContainer(id);
    const exec = await container.exec({
      Cmd: command,
      AttachStdout: true,
      AttachStderr: true,
    });
    const stream = await exec.start({ hijack: true, stdin: false });
    return new Promise((resolve) => {
      const chunks: Buffer[] = [];
      stream.on("data", (chunk: Buffer) => chunks.push(chunk));
      stream.on("end", () => {
        resolve(
          Buffer.concat(chunks)
            .toString("utf-8")
            .replace(/[\x00-\x08]/g, ""), // eslint-disable-line no-control-regex
        );
      });
    });
  }

• src/index.ts:117-132 (registration)

  Registration of the exec_command tool with the MCP server. Defines the tool name, description, input schema, and async handler that calls execCommand and returns the result as text content.

  server.tool(
    "exec_command",
    "Execute a command inside a running Docker container.",
    {
      id: z.string().describe("Container ID or name"),
      command: z
        .array(z.string())
        .describe("Command and arguments, e.g. ['ls', '-la']"),
    },
    async ({ id, command }) => {
      const output = await execCommand(id, command);
      return {
        content: [{ type: "text", text: output || "(no output)" }],
      };
    },
  );

• src/index.ts:120-125 (schema)

  Zod schema definition for exec_command tool inputs: 'id' (string for container ID/name) and 'command' (array of strings for command and arguments).

  {
    id: z.string().describe("Container ID or name"),
    command: z
      .array(z.string())
      .describe("Command and arguments, e.g. ['ls', '-la']"),
  },