languard-servers-manager/MODULES.md

Languard Servers Manager — Python Module Breakdown

Project Structure

backend/
├── main.py
├── config.py
├── database.py
├── dependencies.py
│
├── auth/
│   ├── __init__.py
│   ├── router.py
│   ├── service.py
│   ├── schemas.py
│   └── utils.py
│
├── servers/
│   ├── __init__.py
│   ├── router.py
│   ├── service.py
│   ├── schemas.py
│   ├── process_manager.py
│   └── config_generator.py
│
├── rcon/
│   ├── __init__.py
│   ├── client.py
│   └── service.py
│
├── missions/
│   ├── __init__.py
│   ├── router.py
│   ├── service.py
│   └── schemas.py
│
├── mods/
│   ├── __init__.py
│   ├── router.py
│   ├── service.py
│   └── schemas.py
│
├── players/
│   ├── __init__.py
│   ├── router.py
│   ├── service.py
│   └── schemas.py
│
├── logs/
│   ├── __init__.py
│   ├── router.py
│   ├── service.py
│   └── parser.py
│
├── metrics/
│   ├── __init__.py
│   ├── router.py
│   └── service.py
│
├── websocket/
│   ├── __init__.py
│   ├── router.py
│   ├── manager.py
│   └── broadcaster.py
│
├── threads/
│   ├── __init__.py
│   ├── base_thread.py
│   ├── process_monitor.py
│   ├── log_tail.py
│   ├── metrics_collector.py
│   ├── rcon_poller.py
│   └── thread_registry.py
│
├── system/
│   ├── __init__.py
│   └── router.py
│
├── dal/
│   ├── __init__.py
│   ├── base_repository.py
│   ├── server_repository.py
│   ├── config_repository.py
│   ├── player_repository.py
│   ├── log_repository.py
│   ├── metrics_repository.py
│   ├── mission_repository.py
│   ├── mod_repository.py
│   ├── ban_repository.py
│   └── event_repository.py
│
├── migrations/
│   ├── runner.py
│   └── 001_initial_schema.sql
│
└── utils/
    ├── __init__.py
    ├── crypto.py
    ├── file_utils.py
    └── port_checker.py

---

Module Details

main.py

Entry point. Creates and configures the FastAPI application.

# Responsibilities:
# - Create FastAPI app instance
# - Register all routers with prefix /api
# - Configure CORS middleware
# - Add JWT auth middleware
# - Register startup/shutdown event handlers:
#     startup: run DB migrations, init ProcessManager, restore running servers
#     shutdown: gracefully stop all BroadcastThread, close DB
# - Mount static files if serving frontend
# - NOTE: Route handlers that perform blocking I/O (subprocess, file writes,
#   socket checks) MUST be declared as plain `def` (not `async def`).
#   FastAPI automatically runs plain-def handlers in a thread pool,
#   preventing event loop blocking. Only truly async operations
#   (WebSocket send, async library calls) should use `async def`.

Key functions:
  create_app() -> FastAPI
  on_startup()           # DB migrations, recover state
  on_shutdown()          # Clean up threads, close connections

---

config.py

Loads and validates environment variables using Pydantic BaseSettings.

class Settings(BaseSettings):
    secret_key: str
    encryption_key: str          # Fernet base64 key (NOT hex)
    db_path: str = "./languard.db"
    servers_dir: str = "./servers"
    arma_exe: str = "C:/Arma3Server/arma3server_x64.exe"
    host: str = "0.0.0.0"
    port: int = 8000
    cors_origins: list[str] = ["http://localhost:5173"]
    log_retention_days: int = 7
    metrics_retention_days: int = 30
    player_history_retention_days: int = 90
    jwt_expire_hours: int = 24
    login_rate_limit: str = "5/minute"  # per IP

settings = Settings()  # singleton

---

database.py

Database engine setup and session management.

# Responsibilities:
# - Create SQLAlchemy engine with WAL + FK + busy_timeout pragmas
# - Provide get_db() dependency for FastAPI routes (sync session)
# - Provide get_thread_db() for background threads (thread-local sessions)
# - run_migrations(): apply pending .sql migration files at startup
# - Migration rollback: if a migration fails, the schema_migrations table
#   is NOT updated; re-running applies only unapplied migrations (idempotent)

# Pragma setup:
#   PRAGMA journal_mode=WAL
#   PRAGMA foreign_keys=ON
#   PRAGMA busy_timeout=5000    # 5s wait before "database is locked" error

Key functions:
  get_engine() -> Engine
  get_db() -> Generator[Connection, None, None]   # FastAPI dependency
  get_thread_db() -> Connection                   # for threads
  run_migrations(engine: Engine)

---

dependencies.py

Reusable FastAPI dependencies.

# Responsibilities:
# - get_current_user(token) -> User   (JWT validation)
# - require_admin(user) -> User       (role check)
# - get_server_or_404(server_id, db) -> ServerRow

Key functions:
  get_current_user(credentials: HTTPAuthorizationCredentials) -> User
  require_admin(user: User = Depends(get_current_user)) -> User
  get_server_or_404(server_id: int, db: Connection) -> dict

---

auth/

router.py — FastAPI router for auth endpoints.

• POST /auth/login
• POST /auth/logout
• GET /auth/me
• PUT /auth/password
• GET /auth/users (admin)
• POST /auth/users (admin)
• DELETE /auth/users/{user_id} (admin)

service.py — AuthService

class AuthService:
    def login(username, password) -> TokenResponse
    def create_user(username, password, role) -> User
    def change_password(user_id, current_pw, new_pw) -> bool
    def list_users() -> list[User]
    def delete_user(user_id) -> bool

utils.py

def hash_password(password: str) -> str          # bcrypt
def verify_password(plain, hashed) -> bool
def create_access_token(data: dict) -> str       # JWT sign
def decode_access_token(token: str) -> dict      # JWT verify

---

servers/

router.py — All server CRUD + lifecycle endpoints.

• GET /servers
• POST /servers
• GET /servers/{id}
• PUT /servers/{id}
• DELETE /servers/{id}
• POST /servers/{id}/start
• POST /servers/{id}/stop
• POST /servers/{id}/restart
• POST /servers/{id}/kill
• GET /servers/{id}/config
• PUT /servers/{id}/config/server
• PUT /servers/{id}/config/basic
• PUT /servers/{id}/config/profile
• PUT /servers/{id}/config/launch
• PUT /servers/{id}/config/rcon
• GET /servers/{id}/config/preview
• GET /servers/{id}/config/download/{filename}

service.py — ServerService

class ServerService:
    def list_servers() -> list[ServerSummary]
    def get_server(server_id) -> ServerDetail
    def create_server(data: CreateServerRequest) -> Server
    def update_server(server_id, data) -> Server
    def delete_server(server_id) -> bool

    def start(server_id) -> StatusResponse
      # 1. Load config from DB
      # 2. Validate exe_path exists and basename matches allowlist
      #    (arma3server_x64.exe, arma3server.exe) — prevents executing arbitrary binaries
      # 3. Check ALL derived ports not in use (game_port through game_port+3 + rcon_port)
      # 4. ConfigGenerator.write_all(server_id)
      #    — if write fails: DB status='error', return error (no process launch)
      # 5. Build launch args
      # 6. ProcessManager.start(server_id, exe, args, cwd=servers/{id}/)
      # 7. DB: status = 'starting'
      # 8. ThreadRegistry.start_server_threads(server_id)
      # 9. Broadcast status update

    def stop(server_id, force=False) -> StatusResponse
      # 1. If not force: RConService.send_command('#shutdown')
      # 2. Wait up to 30s for process exit
      # 3. If still running: ProcessManager.kill(server_id)
      # 4. DB: status = 'stopped', pid = NULL
      # 5. ThreadRegistry.stop_server_threads(server_id)
      # 6. PlayerRepository.clear(server_id)
      # 7. Broadcast status update

    def restart(server_id) -> StatusResponse

    def update_config_server(server_id, data) -> ServerConfig
    def update_config_basic(server_id, data) -> BasicConfig
    def update_config_profile(server_id, data) -> ServerProfile
    def update_config_launch(server_id, data) -> LaunchParams
    def update_config_rcon(server_id, data) -> RConConfig
      # Updates rcon_configs row (rcon_password, max_ping, enabled) via ConfigRepository.
      # If data includes rcon_port, also updates servers.rcon_port via ServerRepository —
      # rcon_port lives in the servers table, not rcon_configs.
      # Regenerates battleye/beserver.cfg immediately after saving.
    def get_config_preview(server_id) -> str

process_manager.py — ProcessManager singleton

class ProcessManager:
    _instance = None
    _processes: dict[int, subprocess.Popen] = {}
    _lock: threading.Lock

    @classmethod
    def get() -> ProcessManager

    def start(server_id, exe_path, args: list[str], cwd: str) -> int  # returns PID
      # subprocess.Popen([exe_path, *args], cwd=cwd, stdout=PIPE, stderr=STDOUT)
      # cwd = servers/{server_id}/ so relative config paths resolve correctly

    def stop(server_id, timeout=30) -> bool
      # On Windows: subprocess.terminate() = TerminateProcess (hard kill, no SIGTERM)
      # Graceful shutdown is handled by ServerService via RCon #shutdown first.
      # This method is the forceful fallback: terminate() → wait(timeout)

    def kill(server_id) -> bool
      # terminate() immediately (hard kill on Windows)

    def is_running(server_id) -> bool

    def get_pid(server_id) -> int | None

    def get_process(server_id) -> subprocess.Popen | None

    def list_running() -> list[int]  # list of server_ids

    def recover_on_startup(db)
      # At app startup: query DB for servers with status='running'
      # Check if pid still alive AND verify process name matches arma3server
      # (prevents PID reuse by unrelated processes)
      # If alive: re-attach monitoring threads (skip process start)
      # If dead or wrong process: mark crashed, clear players

config_generator.py — ConfigGenerator

class ConfigGenerator:
    def write_all(server_id: int, db: Connection) -> None
      # Writes server.cfg, basic.cfg, server.Arma3Profile, battleye/beserver.cfg
      # Creates directories if they don't exist
      # Sets restrictive file permissions on files containing passwords:
      # Unix: chmod 0600
      # Windows: use icacls to grant only the service account read/write access
      # Raises IOError if write fails — caller must handle (set DB status='error')

    def write_server_cfg(server_id, config: dict, path: Path) -> None
      # Uses structured builder — NOT f-strings or string.Template
      # Escapes double quotes in all string values (replace " with \"")
      # Validates no newline injection in string fields
      # Renders mission rotation as class Missions { class Mission1 { ... }; };

    def write_basic_cfg(server_id, config: dict, path: Path) -> None

    def write_arma3profile(server_id, profile: dict, path: Path) -> None
      # Writes to servers/{id}/server/server.Arma3Profile (profile subdirectory)

    def write_beserver_cfg(server_id, rcon_config: dict, path: Path) -> None
      # Generates servers/{id}/battleye/beserver.cfg
      # Content: "RConPassword <password>\nRConPort <port>\n"
      # Without this file BattlEye will not open an RCon port.

    def build_launch_args(server_id, config: dict, launch: dict, mod_string: str) -> list[str]
      # Returns list of command-line arguments for arma3server_x64.exe
      # e.g. ['-port=2302', '-config=server.cfg', '-cfg=basic.cfg',
      #        '-profiles=./', '-name=server', '-world=empty',
      #        '-mod=@CBA;@ACE', '-serverMod=@ACE_server',
      #        '-bepath=./battleye',
      #        '-limitFPS=50', '-autoInit', '-loadMissionToMemory', ...]
      # NOTE: -profiles is relative to cwd (which is set to servers/{id}/)
      #       -bepath is required for BattlEye to find beserver.cfg

    def _escape_config_string(value: str) -> str
      # Escapes backslashes FIRST, then double quotes and newlines for safe Arma 3 config interpolation.
      # Order matters: backslash → \\, then " → \", then newline → \\n
      # If backslashes are not escaped first, input "test\\" produces "test\\"
      # which Arma 3 reads as an escaped backslash + unescaped closing quote = injection.
      value = value.replace('\\', '\\\\')  # backslash FIRST
      value = value.replace('"', '\\"')    # then double-quote
      value = value.replace('\n', '\\n')   # then newline
      value = value.replace('\r', '')       # strip carriage returns
      value = value.replace('\t', ' ')      # tabs → spaces
      return value

    def _render_mission_class(rotation: list[dict]) -> str
      # Renders the class Missions {} block for server.cfg
      # class Missions { class Mission1 { template="..."; difficulty="..."; }; ... };

---

rcon/

client.py — BERConClient

class BERConClient:
    """
    Implements BattlEye RCon protocol over UDP.
    Packet type bytes:
      Client → Server: 0xFF 0x00 [password]        → login
      Client → Server: 0xFF 0x01 [seq] [command]   → send command
      Client → Server: 0xFF 0x02                   → keepalive (empty payload)
      Server → Client: 0xFF 0x00 [0x00|0x01]       → login response (0x01=ok)
      Server → Client: 0xFF 0x01 [seq] [response]  → command response
      Server → Client: 0xFF 0x02 [seq] [message]   → unsolicited server message (chat/kill events)
    Note: 0x01 is the type byte for BOTH outgoing commands AND incoming command responses.
    """
    def __init__(host: str, port: int, password: str)

    # Request multiplexer: prevents response misrouting when
    # RConPollerThread and API-request RConService share the same socket.
    _pending_requests: dict[int, threading.Event] = {}   # seq → Event
    _responses: dict[int, str] = {}                        # seq → response
    _seq_counter: int = 0
    _lock: threading.Lock

    def connect() -> bool
    def disconnect()
    def login() -> bool
    def send_command(command: str, timeout: float = 5.0) -> str | None
      # Sends command with sequence number, creates Event, waits for response
      # Routes response to correct caller by matching sequence byte
    def keepalive()                # send empty packet every 30s
    def is_connected() -> bool

    # Background receiver thread:
    def _receiver_loop()
      # Reads all incoming UDP packets
      # For type 0x01 (command response): sets Event + stores response for matching seq
      # For type 0x02 (server message): enqueues for processing (player events, chat)

    def parse_players_response(response: str) -> list[PlayerInfo]
      # Parse output of 'players' command
      # Format: "Players on server:\n[#] [IP:Port] [Ping] [GUID] [Name]\n..."

service.py — RConService

class RConService:
    def __init__(server_id: int)

    def send_command(command: str) -> str | None
      # Gets or creates BERConClient, sends command, returns response

    def kick_player(player_num: int, reason: str = "") -> bool

    def ban_player(player_num: int, duration_minutes: int, reason: str) -> bool

    def unban(guid: str) -> bool

    def say_all(message: str) -> bool

    def get_players() -> list[PlayerInfo]

    def send_mission_command(mission_name: str) -> bool

    def shutdown() -> bool

    def restart() -> bool

    def lock() -> bool

    def unlock() -> bool

---

missions/

service.py — MissionService

class MissionService:
    def list_missions(server_id) -> list[Mission]

    def upload_mission(server_id, filename: str, file_data: bytes) -> Mission
      # 1. Validate .pbo extension
      # 2. Parse mission_name and terrain from filename
      # 3. Write to servers/{server_id}/mpmissions/{filename}
      # 4. Insert into missions table
      # 5. Return Mission object

    def delete_mission(server_id, mission_id) -> bool
      # 1. Check not in active rotation
      # 2. Delete file from disk
      # 3. Delete from DB

    def get_rotation(server_id) -> list[RotationEntry]

    def update_rotation(server_id, rotation: list[RotationEntry]) -> bool
      # 1. Delete existing rotation rows
      # 2. Insert new ordered list
      # 3. Trigger config regeneration

---

mods/

service.py — ModService

class ModService:
    def list_all() -> list[Mod]
    def register_mod(name, folder_path, workshop_id, description) -> Mod
      # Validates folder exists
    def delete_mod(mod_id) -> bool
      # Check not in use by any server
    def get_server_mods(server_id) -> list[ServerMod]
    def update_server_mods(server_id, mods: list) -> bool
      # Replaces server_mods rows, regenerates mod string
    def build_mod_string(server_id) -> tuple[str, str]
      # Returns (-mod=..., -serverMod=...) strings

---

players/

service.py — PlayerService

class PlayerService:
    def get_current_players(server_id) -> list[Player]
    def kick(server_id, player_num, reason) -> bool
      # RConService.kick_player() + log event
    def ban(server_id, player_num, duration_minutes, reason) -> bool
      # RConService.ban_player() + insert into bans table
    def get_history(server_id, limit, offset, search) -> PaginatedResult
    def update_from_rcon(server_id, rcon_players: list) -> None
      # Upsert players table; detect disconnections; insert player_history rows

---

logs/

parser.py — RPTParser

class RPTParser:
    # Parses Arma 3 RPT log format
    # Example line: "10:05:23 BattlEye Server: Initialized (v1.240)"
    # With timestamp format "short": "10:05:23"
    # With timestamp format "full": "2026/04/16, 10:05:23"

    def parse_line(line: str) -> LogEntry | None
      # Returns: {timestamp, level, message}
      # level detection: 'error' if 'Error' in msg, 'warning' if 'Warning', else 'info'

    def parse_timestamp(raw: str) -> datetime

service.py — LogService

class LogService:
    def query(server_id, limit, offset, level, since, search) -> PaginatedLogs
    def clear(server_id) -> int  # returns deleted count
    def get_rpt_path(server_id) -> Path | None
      # Delegates to file_utils.get_rpt_path() — globs for latest timestamped .rpt
    def cleanup_old_logs()  # called by APScheduler

---

metrics/

service.py — MetricsService

class MetricsService:
    def query(server_id, from_dt, to_dt, resolution) -> list[MetricPoint]
      # Aggregates by resolution ('1m', '5m', '1h')
    def insert(server_id, cpu, ram, player_count) -> None
    def cleanup_old_metrics()  # called by APScheduler
    def get_latest(server_id) -> MetricPoint | None

---

websocket/

manager.py — ConnectionManager

class ConnectionManager:
    """
    Manages active WebSocket connections grouped by server_id.
    'all' is a special server_id that receives events for all servers.
    """
    _connections: dict[str, set[WebSocket]]
    _lock: asyncio.Lock

    async def connect(ws: WebSocket, server_id: str, channels: list[str])
    async def disconnect(ws: WebSocket, server_id: str)
    async def broadcast(server_id: str, message: dict)
      # Sends to all connections subscribed to server_id + 'all'
    async def send_personal(ws: WebSocket, message: dict)

broadcaster.py — BroadcastThread

class BroadcastThread(threading.Thread):
    """
    Runs in background thread.
    Reads from a queue (put by background threads).
    Posts messages to asyncio event loop via run_coroutine_threadsafe().
    """
    _queue: queue.Queue
    _loop: asyncio.AbstractEventLoop
    _manager: ConnectionManager
    _running: bool

    def run()  # main loop: get from queue, schedule broadcast coroutine

    @staticmethod
    def enqueue(server_id: int, msg_type: str, data: dict)
      # Thread-safe: called from any background thread

router.py — WebSocket endpoint

@router.websocket("/ws/{server_id}")
async def websocket_endpoint(ws: WebSocket, server_id: str, token: str = Query(...)):
    # 1. Validate JWT token from query param
    # 2. Accept WebSocket connection
    # 3. Register with ConnectionManager
    # 4. Loop: receive messages (ping/subscribe/unsubscribe)
    # 5. On disconnect: deregister from ConnectionManager

---

threads/

base_thread.py — BaseServerThread

class BaseServerThread(threading.Thread):
    def __init__(server_id: int, interval: float)
    def stop()            # sets _stop_event
    def is_stopped() -> bool
    def run()             # creates thread-local DB connection, calls setup(),
                          # then loops: tick(self._db) + wait(interval)
                          # finally calls teardown() in finally block
    def setup()           # override for init work (receives self._db)
    def tick()            # override for per-interval work (uses self._db)
    def teardown()        # override for cleanup (close files, sockets)
    def on_error(e: Exception)  # default: log, continue
                              # if same error repeats 5x in a row: escalate + self.stop()

process_monitor.py — ProcessMonitorThread

class ProcessMonitorThread(BaseServerThread):
    interval = 1.0  # seconds

    def tick():
        # 1. Check if process is still alive (os.kill(pid, 0))
        # 2. If dead:
        #    a. Get exit code
        #    b. DB: status = 'crashed', stopped_at = now
        #    c. Clear players from DB
        #    d. Broadcast: {type: 'status', status: 'crashed'}
        #    e. Insert server_events: {event_type: 'crashed', exit_code}
        #    f. If auto_restart enabled and restart_count < max_restarts:
        #         DB: increment restart_count
        #         Schedule restart after 10s (threading.Timer)
        #    g. self.stop()

log_tail.py — LogTailThread

class LogTailThread(BaseServerThread):
    interval = 0.1  # 100ms

    def setup():
        # Find .rpt file path
        # Open file, seek to end (tail behavior)
        self._file = open(rpt_path, 'r', encoding='utf-8', errors='replace')
        self._file.seek(0, 2)  # seek to end

    def tick():
        # 1. Read all new lines from self._file
        # 2. For each line:
        #    a. RPTParser.parse_line(line) -> LogEntry
        #    b. LogRepository.insert(server_id, entry)
        #    c. BroadcastThread.enqueue(server_id, 'log', entry)

    def on_rpt_rotate():
        # Close and reopen if file was rotated (new server start)

metrics_collector.py — MetricsCollectorThread

class MetricsCollectorThread(BaseServerThread):
    interval = 5.0  # seconds

    def tick():
        # 1. Get PID from ProcessManager
        # 2. psutil.Process(pid).cpu_percent(interval=0.5)
        # 3. psutil.Process(pid).memory_info().rss / (1024*1024)  # MB
        # 4. PlayerRepository.count(server_id) -> player_count
        # 5. MetricsRepository.insert(server_id, cpu, ram, player_count)
        # 6. BroadcastThread.enqueue(server_id, 'metrics', {cpu, ram, player_count})

rcon_poller.py — RConPollerThread

class RConPollerThread(BaseServerThread):
    interval = 10.0   # seconds
    startup_delay = 30.0  # wait 30s after server start before first poll
    _rcon_ready = False   # flag: set True only after successful setup

    def setup():
        # Use _stop_event.wait() instead of time.sleep() so the thread
        # can be interrupted immediately during shutdown
        if self._stop_event.wait(self.startup_delay):
            self._rcon_ready = False
            return  # stop was requested during startup delay
        self._rcon = RConService(self.server_id)
        self._rcon_ready = True

    def tick():
        if not self._rcon_ready:
            return  # setup() failed or was interrupted — skip tick
        # 1. RConService.get_players() -> list[PlayerInfo]
        # 2. PlayerService.update_from_rcon(server_id, players)
        # 3. BroadcastThread.enqueue(server_id, 'players', {players, count})
        # 4. RConClient.keepalive() if needed

thread_registry.py — ThreadRegistry

class ThreadRegistry:
    """
    Singleton. Manages all background threads per server.
    """
    _threads: dict[int, dict[str, BaseServerThread]]
    _lock: threading.Lock

    @classmethod
    def get() -> ThreadRegistry

    def start_server_threads(server_id: int) -> None
      # Instantiates and starts:
      #   ProcessMonitorThread, LogTailThread,
      #   MetricsCollectorThread, RConPollerThread

    def stop_server_threads(server_id: int) -> None
      # Calls stop() on each thread; joins with timeout

    def get_thread(server_id, thread_type: str) -> BaseServerThread | None

    def list_active(server_id) -> list[str]  # thread names

    def stop_all() -> None  # on app shutdown

---

dal/

base_repository.py

class BaseRepository:
    def __init__(db: Connection)

    def execute(sql: str, params: tuple = ()) -> CursorResult
    def fetchone(sql: str, params: tuple = ()) -> dict | None
    def fetchall(sql: str, params: tuple = ()) -> list[dict]
    def insert(table: str, data: dict) -> int  # returns last_insert_rowid
    def update(table: str, data: dict, where: str, params: tuple) -> int
    def delete(table: str, where: str, params: tuple) -> int
    def row_to_dict(row) -> dict

server_repository.py

class ServerRepository(BaseRepository):
    def get_all() -> list[dict]
    def get_by_id(server_id) -> dict | None
    def create(data: dict) -> int
    def update_status(server_id, status, pid=None, started_at=None) -> None
    def update(server_id, data: dict) -> None
    def delete(server_id) -> None
    def get_running() -> list[dict]  # for startup recovery
    def increment_restart_count(server_id) -> None
    def reset_restart_count(server_id) -> None

event_repository.py

class ServerEventRepository(BaseRepository):
    def insert(server_id: int, event_type: str, actor: str, detail: dict) -> int
    def get_events(server_id: int, limit: int, offset: int, event_type: str | None) -> list[dict]
    def get_recent(server_id: int, limit: int = 20) -> list[dict]

config_repository.py

class ConfigRepository(BaseRepository):
    def get_server_config(server_id) -> dict | None
    def upsert_server_config(server_id, data: dict) -> None
    def get_basic_config(server_id) -> dict | None
    def upsert_basic_config(server_id, data: dict) -> None
    def get_profile(server_id) -> dict | None
    def upsert_profile(server_id, data: dict) -> None
    def get_launch_params(server_id) -> dict | None
    def upsert_launch_params(server_id, data: dict) -> None
    def get_rcon_config(server_id) -> dict | None
    def upsert_rcon_config(server_id, data: dict) -> None
    def get_full_config(server_id) -> dict  # all sections combined

---

system/

router.py — System-level endpoints (no auth required for health check).

# GET /system/status  → running_servers, total_servers, uptime, version
# GET /system/health  → 200 OK if app is alive (for load balancer / Docker healthcheck)

@router.get("/system/status")
async def system_status() -> APIResponse:
    # Returns: {version, running_servers, total_servers, uptime_seconds}

@router.get("/system/health")
async def health_check() -> dict:
    # Returns: {"status": "ok"}

---

utils/

crypto.py

# AES-256 field encryption for sensitive values (passwords, RCon pw)
# Uses cryptography.fernet.Fernet

def encrypt(plaintext: str) -> str
def decrypt(ciphertext: str) -> str
def get_fernet() -> Fernet  # from settings.encryption_key

file_utils.py

def ensure_server_dirs(server_id: int) -> None
  # Creates servers/{id}/, servers/{id}/server/ (profile dir),
  # servers/{id}/mpmissions/, servers/{id}/battleye/

def get_server_dir(server_id: int) -> Path
def get_profile_dir(server_id: int) -> Path
  # Returns servers/{id}/server/ — Arma 3 profile dir (matches -name=server)
def get_missions_dir(server_id: int) -> Path
def get_rpt_path(server_id: int) -> Path | None
  # Arma 3 creates timestamped RPT files in the profile dir:
  #   servers/{id}/server/arma3server_YYYY-MM-DD_HH-MM-SS.rpt
  # Uses rglob('*.rpt') to search recursively within profile dir.
  # Returns the most-recently-modified one.
  # Returns None if no .rpt file exists yet (server still starting up).
def safe_delete_file(path: Path) -> bool
def sanitize_filename(filename: str) -> str
  # Returns Path(filename).name — prevents path traversal on both Unix and Windows
  # os.path.basename() on Windows does NOT strip forward slashes;
  # Path.name handles both separators correctly.

port_checker.py

def is_port_in_use(port: int, host: str = "0.0.0.0") -> bool
  # socket.connect check

def check_server_ports_available(game_port: int, rcon_port: int | None = None, host: str = "0.0.0.0") -> list[int]
  # Checks ALL ports: game_port, game_port+1 (Steam query),
  # game_port+2 (VON), game_port+3 (Steam auth),
  # plus the actual rcon_port (user-configurable, defaults to game_port+4)
  # If rcon_port is None, defaults to game_port+4
  # If rcon_port is None, defaults to game_port+4
  # Returns list of ports that are in use (empty = all available)

def find_available_port(start: int = 2302, step: int = 100) -> int
  # Find next available game port (checking all 5 derived ports per candidate)

---

Key Dependencies (requirements.txt)

fastapi==0.111.0
uvicorn[standard]==0.29.0
pydantic==2.7.0
pydantic-settings==2.2.1
sqlalchemy==2.0.30
python-jose[cryptography]==3.3.0   # JWT
passlib[bcrypt]==1.7.4  # password hashing
cryptography==42.0.5    # field-level encryption (Fernet)
psutil==5.9.8           # process metrics
apscheduler==3.10.4     # scheduled jobs (log/metrics/player_history cleanup)
python-multipart==0.0.9 # file upload support
slowapi==0.1.9          # rate limiting middleware
uvloop==0.19.0; sys_platform != "win32"  # faster event loop (Linux/macOS only — skip on Windows)