JMeter MCP Server

Instructions

Implementation Reference

• jmeter_server.py:82-90 (handler)

  Primary handler for the 'execute_jmeter_test' tool. Registered with @mcp.tool() decorator. Handles input parameters and delegates to the run_jmeter helper function.

  @mcp.tool()
  async def execute_jmeter_test(test_file: str, gui_mode: bool = False) -> str:
      """Execute a JMeter test.
  
      Args:
          test_file: Path to the JMeter test file (.jmx)
          gui_mode: Whether to run in GUI mode (default: False)
      """
      return await run_jmeter(test_file, non_gui=not gui_mode)  # Run in non-GUI mode by default

• jmeter_server.py:22-80 (helper)

  Core helper function that performs file validation, constructs the JMeter subprocess command, executes it, and handles output/errors for both GUI and non-GUI modes.

  async def run_jmeter(test_file: str, non_gui: bool = True) -> str:
      """Run a JMeter test.
  
      Args:
          test_file: Path to the JMeter test file (.jmx)
          non_gui: Run in non-GUI mode (default: True)
  
      Returns:
          str: JMeter execution output
      """
      try:
          # Convert to absolute path
          test_file_path = Path(test_file).resolve()
          
          # Validate file exists and is a .jmx file
          if not test_file_path.exists():
              return f"Error: Test file not found: {test_file}"
          if not test_file_path.suffix == '.jmx':
              return f"Error: Invalid file type. Expected .jmx file: {test_file}"
  
          # Get JMeter binary path from environment
          jmeter_bin = os.getenv('JMETER_BIN', 'jmeter')
          java_opts = os.getenv('JMETER_JAVA_OPTS', '')
  
          # Log the JMeter binary path and Java options
          logger.info(f"JMeter binary path: {jmeter_bin}")
          logger.debug(f"Java options: {java_opts}")
  
          # Build command
          cmd = [str(Path(jmeter_bin).resolve())]
          
          if non_gui:
              cmd.extend(['-n'])
          cmd.extend(['-t', str(test_file_path)])
  
          # Log the full command for debugging
          logger.debug(f"Executing command: {' '.join(cmd)}")
          
          if non_gui:
              # For non-GUI mode, capture output
              result = subprocess.run(cmd, capture_output=True, text=True)
              
              # Log output for debugging
              logger.debug("Command output:")
              logger.debug(f"Return code: {result.returncode}")
              logger.debug(f"Stdout: {result.stdout}")
              logger.debug(f"Stderr: {result.stderr}")
  
              if result.returncode != 0:
                  return f"Error executing JMeter test:\n{result.stderr}"
              
              return result.stdout
          else:
              # For GUI mode, start process without capturing output
              subprocess.Popen(cmd)
              return "JMeter GUI launched successfully"
  
      except Exception as e:
          return f"Unexpected error: {str(e)}"