Building a Lightweight EXFO Tester Admin Panel with FastAPI and Alpine.js

In this post, I’ll walk you through how to build a lightweight web application that integrates with EXFO tester APIs, allows for user authentication, and fetches test results using FastAPI and Alpine.js.

Why FastAPI + Alpine.js?

FastAPI is a modern, async-ready web framework perfect for building APIs and backend systems.
Alpine.js is a minimal JavaScript framework that allows you to add interactivity without needing a heavy frontend like React or Vue.
Together, they create a clean, fast, and powerful stack ideal for internal admin panels or embedded control apps.

Key Features

Session-based login system (username + password)
Authentication-protected API endpoints
A single HTML page that dynamically fetches test results after login
EXFO integration placeholder for real test results

Tech Stack

Backend: FastAPI
Frontend: HTML + TailwindCSS + Alpine.js
Auth: Session-based with cookie storage
API: Mock EXFO test result endpoint

Basic Fiber Optic Terms

Before diving into EXFO testing, it's helpful to understand some key fiber optic terms:

OLT (Optical Line Terminal): The central device at the telecom provider that sends data to multiple ONUs.
ONU/ONT (Optical Network Unit/Terminal): The device at the user's location that receives data from the OLT.
PON (Passive Optical Network): A point-to-multipoint fiber network that uses unpowered splitters.
GPON/XGS-PON: Standards for PONs offering different speeds (GPON = 2.5 Gbps down; XGS-PON = 10 Gbps symmetrically).
dBm: Measurement unit for optical signal power.

How to Configure an EXFO PON Tester (Basics)

Connect the Tester
- Plug the fiber cable from the splitter or drop cable into the EXFO tester's "ONT" port.
- Optionally connect the ONU to the tester's "PON" output port for inline testing.
Select PON Mode
- Choose between GPON, XGS-PON, or dual-mode depending on your deployment.
Power Measurement
- Start a power test to check downstream (OLT) and upstream (ONT) signal levels.
- Typical acceptable range: –8 dBm to –27 dBm.
Pass/Fail Results
- The tester will display whether levels are within thresholds.
- Adjust thresholds manually if needed to match your network standard.
Save/Export Results
- Use USB or API integration to export results to your backend or PC.

System Deployment Diagram (Mermaid.js)

graph TD
    A["EXFO Tester"] --> B["FastAPI Server"]
    B --> C["Session Auth API"]
    B --> D["Test Results API"]
    D --> E["MongoDB (optional)"]
    B --> F["Static HTML + Alpine.js"]
    F --> G["User Browser"]
    G -->|login| C
    G -->|view data| D

ONT + EXFO Tester Configuration Flow (Mermaid.js)

graph LR
    Start["Start"] --> Splitter["Connect Drop Fiber to EXFO Tester (ONT Port)"]
    Splitter --> InlineTest["(Optional) Connect ONU to PON Port for Inline Test"]
    InlineTest --> Mode["Select PON Mode: GPON / XGS-PON"]
    Mode --> PowerTest["Run Optical Power Test"]
    PowerTest --> Result["Check Signal Levels: OLT RX / ONT TX"]
    Result --> Decision{"Within Acceptable Range?"}
    Decision -- Yes --> Save["Save / Export Result"]
    Decision -- No --> Adjust["Adjust Fiber or Ports and Retest"]
    Save --> Done["Done"]
    Adjust --> PowerTest

EXFO Tester Physical Setup Diagram (Mermaid.js)

graph TD
    A["OLT (Central Office)"] --> B["Splitter"]
    B --> C["Drop Fiber"]
    C --> D["EXFO Tester (ONT Port)"]
    D -->|optional| E["PON Port to ONU"]
    E --> F["User Premises / ONU Device"]

This diagram shows the standard setup for inline testing using an EXFO tester. The drop fiber is connected to the ONT port, and optionally, the ONU can be connected to the PON port so the tester sits inline and does not interrupt service.

graph LR
    Start["Start"] --> Splitter["Connect Drop Fiber to EXFO Tester (ONT Port)"]
    Splitter --> InlineTest["(Optional) Connect ONU to PON Port for Inline Test"]
    InlineTest --> Mode["Select PON Mode: GPON / XGS-PON"]
    Mode --> PowerTest["Run Optical Power Test"]
    PowerTest --> Result["Check Signal Levels: OLT RX / ONT TX"]
    Result --> Decision{"Within Acceptable Range?"}
    Decision -- Yes --> Save["Save / Export Result"]
    Decision -- No --> Adjust["Adjust Fiber or Ports and Retest"]
    Save --> Done["Done"]
    Adjust --> PowerTest

graph TD
    A["EXFO Tester"] --> B["FastAPI Server"]
    B --> C["Session Auth API"]
    B --> D["Test Results API"]
    D --> E["MongoDB (optional)"]
    B --> F["Static HTML + Alpine.js"]
    F --> G["User Browser"]
    G -->|login| C
    G -->|view data| D

1. Project Setup

Install dependencies:

pip install fastapi uvicorn python-multipart jinja2

Directory structure:

project/
├── main.py
└── templates/
    └── index.html

2. FastAPI Backend Code (`main.py`)

from fastapi import FastAPI, Request, Form
from fastapi.responses import RedirectResponse, JSONResponse
from fastapi.templating import Jinja2Templates
from starlette.middleware.sessions import SessionMiddleware

app = FastAPI()
app.add_middleware(SessionMiddleware, secret_key="supersecret")
templates = Jinja2Templates(directory="templates")

users = {"admin": {"password": "1234"}}
fake_data = [
    {"id": 1, "onu": "ONU123", "status": "PASS"},
    {"id": 2, "onu": "ONU456", "status": "FAIL"},
]

def get_current_user(request: Request):
    return request.session.get("user")

@app.get("/")
def index(request: Request):
    user = get_current_user(request)
    return templates.TemplateResponse("index.html", {"request": request, "user": user})

@app.post("/login")
def login(request: Request, username: str = Form(...), password: str = Form(...)):
    if username in users and users[username]["password"] == password:
        request.session["user"] = username
        return RedirectResponse("/", status_code=303)
    return RedirectResponse("/?error=1", status_code=303)

@app.get("/logout")
def logout(request: Request):
    request.session.clear()
    return RedirectResponse("/", status_code=303)

@app.get("/api/test-results")
def get_test_data(request: Request):
    if not get_current_user(request):
        return JSONResponse(status_code=401, content={"detail": "Unauthorized"})
    return fake_data

3. HTML + Alpine.js Frontend (`templates/index.html`)

<!DOCTYPE html>
<html lang="en" x-data="testApp()" x-init="init()">
<head>
  <script src="https://cdn.jsdelivr.net/npm/alpinejs" defer></script>
  <link href="https://cdn.jsdelivr.net/npm/tailwindcss@2.2.19/dist/tailwind.min.css" rel="stylesheet">
  <title>EXFO Admin Panel</title>
</head>
<body class="p-6 bg-gray-100">
  <div class="max-w-xl mx-auto bg-white p-6 rounded shadow text-center">

    <template x-if="!loggedIn">
      <form method="POST" action="/login" class="space-y-4">
        <h2 class="text-xl font-bold">Login</h2>
        <input type="text" name="username" placeholder="Username" class="border p-2 w-full">
        <input type="password" name="password" placeholder="Password" class="border p-2 w-full">
        <button type="submit" class="bg-blue-600 text-white px-4 py-2 rounded">Login</button>
      </form>
    </template>

    <template x-if="loggedIn">
      <div>
        <h2 class="text-xl font-bold mb-4">Test Results</h2>
        <a href="/logout" class="text-sm text-blue-600 underline">Logout</a>
        <ul class="mt-4 space-y-2 text-left">
          <template x-for="item in testResults" :key="item.id">
            <li class="p-2 border rounded">
              <strong x-text="item.onu"></strong> - <span x-text="item.status"></span>
            </li>
          </template>
        </ul>
      </div>
    </template>
  </div>

  <script>
    function testApp() {
      return {
        loggedIn: {{ 'true' if user else 'false' }},
        testResults: [],
        async init() {
          if (this.loggedIn) {
            try {
              const res = await fetch('/api/test-results');
              if (res.ok) {
                this.testResults = await res.json();
              }
            } catch (err) {
              console.error("Error fetching test results", err);
            }
          }
        }
      }
    }
  </script>
</body>
</html>