<p align="center">
  <img src="images/architecture-diagram.png" width="50%" alt="Architecture Diagram">
</p>

# 🧠 Update Manager Architecture

This document describes how Update Manager is structured internally and how data flows through the system.

---

## Overview

Update Manager is a lightweight, SSH-based system for managing updates across multiple Linux hosts.

It consists of two main layers:

* **UI layer** – interactive menu (`update-manager-ui.sh`)
* **Core engine** – update logic (`update-manager.sh`)

The system is designed to be simple, transparent, and dependency-light.

---

## High-Level Flow

```text
User
  ↓
UI (update-manager-ui.sh)
  ↓
Core (update-manager.sh)
  ↓
SSH → Remote Hosts
  ↓
Results
  ↓
Logging (/opt/update-manager/log)
  ↓
UI / User
```

---

## Components

### UI Layer (`update-manager-ui.sh`)

Responsible for:

* Displaying menu (via `dialog`)
* Handling user input
* Managing hosts (add/remove/edit)
* Providing access to logs
* Delegating actions to core engine

The UI does **not perform updates directly**.

---

### Core Engine (`update-manager.sh`)

Responsible for:

* Reading configuration
* Parsing hosts file
* Executing SSH commands
* Checking for updates (`apt list --upgradable`)
* Handling connection errors
* Writing structured logs

This is the **execution layer** of the system.

---

### Hosts Configuration

File:

```bash
/opt/update-manager/hosts.conf
```

Format:

```text
name    ip    user
```

Example:

```text
server1       192.168.1.10    user
server2       192.168.1.20    user
server3       192.168.1.30    user
```

Each line represents a target system accessed via SSH.

---

### Logging System

Log file:

```bash
/opt/update-manager/log/update-manager.log
```

Log format:

```text
YYYY-MM-DD HH:MM:SS [LEVEL] host - message
```

Example:

```text
2026-03-18 20:45:01 [INFO] lanx-www - Checking updates
2026-03-18 20:45:03 [OK] lanx-www - 3 updates available
2026-03-18 20:45:05 [ERR] lanx-db - Connection failed
```

#### Log Levels

* `INFO` – informational messages
* `OK` – successful operations
* `ERR` – errors or failures

Logging is centralized and written locally.

---

## Execution Flow

For each host:

1. Read host entry from `hosts.conf`
2. Establish SSH connection
3. Execute:

```bash
apt list --upgradable
```

4. Parse output
5. Determine:

   * Up-to-date
   * Updates available
   * Connection failure
6. Write result to:

   * terminal output
   * log file

---

## Configuration

Primary config:

```bash
/etc/update-manager.conf
```

Fallback:

```bash
./update-manager.conf
```

Supported options:

* `HOSTS_FILE`
* `SSH_OPTIONS`

---

## Design Principles

* **No agents** – uses standard SSH only
* **Simple over complex** – minimal dependencies
* **Transparent behavior** – everything is visible/logged
* **CLI-first** – designed for terminal environments
* **Modular growth** – prepared for future extensions

---

## Future Architecture Direction

Planned extensions:

* Plugin system (modular features)
* Web interface (optional UI layer)
* Notification system (alerts)
* Metrics / monitoring
* Integration with Lanx AI

---

## Summary

Update Manager follows a clean separation:

* UI = interaction
* Core = execution
* Config = data
* Log = output

This keeps the system predictable, debuggable, and easy to extend.