As a greeter, I need to handle offline mode in the UI

[guimard]

User Story

As the LightDM greeter,
I need to handle offline mode in the UI,
So that users know when they're authenticating locally vs SSO.

Acceptance Criteria

• Detect when LLNG server is unreachable
• Display offline mode UI (username + local password)
• Show cache expiration date
• First login: prompt for local password creation after SSO
• Clear visual indicator of offline status

Technical Details

Online Mode (First Login)

┌─────────────────────────────────────┐
│  [iframe SSO LLNG]                  │
│  ... SSO authentication ...         │
│                                     │
│  ✓ Authentication successful        │
│                                     │
│  Create a local password for        │
│  offline access:                    │
│                                     │
│  Password: [______________]         │
│  Confirm:  [______________]         │
│                                     │
│  [Skip]  [Create]                   │
└─────────────────────────────────────┘

Offline Mode

┌─────────────────────────────────────┐
│  ⚠ Offline Mode                     │
│  (SSO server unreachable)           │
│                                     │
│  Username: [______________]         │
│  Password: [______________]         │
│                                     │
│  [Login]                            │
│                                     │
│  Cache valid until: 2024-12-23      │
└─────────────────────────────────────┘

Implementation

// greeter/js/offline.js

async function checkServerAvailability() {
    try {
        await fetch(portalUrl + '/ping', { timeout: 5000 });
        return true;
    } catch {
        return false;
    }
}

async function initGreeter() {
    const online = await checkServerAvailability();
    if (online) {
        showSSOFrame();
    } else {
        showOfflineLogin();
    }
}

Files to Create

• greeter/js/offline.js (new)
• Modifications to greeter/index.html
• Modifications to greeter/css/style.css

Component

Repo: llng-pam-module