haproxy-mcp/haproxy_mcp/haproxy_client.py

"""HAProxy Runtime API client functions."""

import socket
import subprocess
import select
import time

from .config import (
    HAPROXY_SOCKET,
    HAPROXY_CONTAINER,
    SOCKET_TIMEOUT,
    SOCKET_RECV_TIMEOUT,
    MAX_RESPONSE_SIZE,
    SUBPROCESS_TIMEOUT,
)
from .exceptions import HaproxyError


def haproxy_cmd(command: str) -> str:
    """Send command to HAProxy Runtime API.

    Args:
        command: The HAProxy runtime API command to execute

    Returns:
        The response from HAProxy

    Raises:
        HaproxyError: If connection fails, times out, or response exceeds size limit
    """
    try:
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
            s.settimeout(SOCKET_TIMEOUT)
            s.connect(HAPROXY_SOCKET)
            s.sendall(f"{command}\n".encode())
            s.shutdown(socket.SHUT_WR)

            # Set socket to non-blocking for select-based recv loop
            s.setblocking(False)
            response = b""
            start_time = time.time()

            while True:
                # Check for overall timeout
                elapsed = time.time() - start_time
                if elapsed >= SOCKET_RECV_TIMEOUT:
                    raise HaproxyError(f"Response timeout after {SOCKET_RECV_TIMEOUT} seconds")

                # Wait for data with timeout (remaining time)
                remaining = SOCKET_RECV_TIMEOUT - elapsed
                ready, _, _ = select.select([s], [], [], min(remaining, 1.0))

                if ready:
                    data = s.recv(8192)
                    if not data:
                        break
                    response += data
                    if len(response) > MAX_RESPONSE_SIZE:
                        raise HaproxyError(f"Response exceeded {MAX_RESPONSE_SIZE} bytes limit")

            return response.decode().strip()
    except socket.timeout:
        raise HaproxyError("Connection timeout")
    except ConnectionRefusedError:
        raise HaproxyError("Connection refused - HAProxy not running?")
    except UnicodeDecodeError:
        raise HaproxyError("Invalid UTF-8 in response")
    except HaproxyError:
        raise
    except Exception as e:
        raise HaproxyError(str(e)) from e


def haproxy_cmd_checked(command: str) -> str:
    """Send command to HAProxy and raise on error response.

    Args:
        command: HAProxy command to execute

    Returns:
        Command response

    Raises:
        HaproxyError: If HAProxy returns an error message
    """
    result = haproxy_cmd(command)
    _check_response_for_errors(result)
    return result


def _check_response_for_errors(response: str) -> None:
    """Check HAProxy response for error indicators.

    Args:
        response: Response string from HAProxy

    Raises:
        HaproxyError: If response contains error indicators
    """
    error_indicators = ["No such", "not found", "error", "failed", "invalid", "unknown"]
    if response:
        response_lower = response.lower()
        for indicator in error_indicators:
            if indicator.lower() in response_lower:
                raise HaproxyError(f"HAProxy command failed: {response.strip()}")


def haproxy_cmd_batch(commands: list[str]) -> list[str]:
    """Send multiple commands to HAProxy.

    Note: HAProxy Runtime API only processes the first command when multiple
    commands are sent on a single connection. This function sends each command
    on a separate connection to ensure all commands are executed.

    Args:
        commands: List of HAProxy commands to execute

    Returns:
        List of responses for each command

    Raises:
        HaproxyError: If connection fails or any command returns an error
    """
    if not commands:
        return []

    if len(commands) == 1:
        return [haproxy_cmd_checked(commands[0])]

    # Send each command on separate connection (HAProxy limitation)
    responses = []
    for cmd in commands:
        try:
            resp = haproxy_cmd_checked(cmd)
            responses.append(resp)
        except HaproxyError:
            raise

    return responses


def reload_haproxy() -> tuple[bool, str]:
    """Validate and reload HAProxy configuration.

    Returns:
        Tuple of (success, message)
    """
    try:
        validate = subprocess.run(
            ["podman", "exec", HAPROXY_CONTAINER, "haproxy", "-c", "-f", "/usr/local/etc/haproxy/haproxy.cfg"],
            capture_output=True, text=True, timeout=SUBPROCESS_TIMEOUT
        )
        if validate.returncode != 0:
            return False, f"Config validation failed:\n{validate.stderr}"

        result = subprocess.run(
            ["podman", "kill", "--signal", "USR2", HAPROXY_CONTAINER],
            capture_output=True, text=True, timeout=SUBPROCESS_TIMEOUT
        )
        if result.returncode != 0:
            return False, f"Reload failed: {result.stderr}"
        return True, "OK"
    except subprocess.TimeoutExpired:
        return False, f"Command timed out after {SUBPROCESS_TIMEOUT} seconds"
    except FileNotFoundError:
        return False, "podman command not found"
    except OSError as e:
        return False, f"OS error: {e}"