Full project: Delonix Temp

From zero to a service on the public internet — build, run, and a real URL, in 4 commands. Everything in this guide was actually run; the output is real, copied from the run.

A real-time API in FastAPI — looks up the CURRENT temperature of any city (via Open-Meteo, no API key) and serves a page that refreshes itself every 30s. The goal is to walk the full Delonix cycle in one small project: multi-stage build → container run → expose to the internet with tunnel. The complete files are in examples/delonix-temp/ — git clone it and follow the steps below exactly as they are.

1. The app

Three files. main.py — two routes: /api/weather/{city} (geocodes the city, asks for the current temperature, returns JSON) and / (an HTML page that calls the API itself via fetch and redoes it every 30s):

from fastapi import FastAPI, HTTPException
from fastapi.responses import HTMLResponse
import httpx

app = FastAPI(title="Delonix Temp")

@app.get("/api/weather/{city}")
async def weather(city: str):
    async with httpx.AsyncClient(timeout=8.0) as client:
        geo = await client.get("https://geocoding-api.open-meteo.com/v1/search",
                                params={"name": city, "count": 1})
        place = geo.json()["results"][0]
        fc = await client.get("https://api.open-meteo.com/v1/forecast", params={
            "latitude": place["latitude"], "longitude": place["longitude"],
            "current": "temperature_2m,weather_code",
        })
    current = fc.json()["current"]
    return {"city": place["name"], "country": place.get("country"),
            "temperature_c": current["temperature_2m"], "observed_at": current["time"]}

@app.get("/", response_class=HTMLResponse)
async def index():
    return PAGE  # HTML with a <script> that fetch("/api/weather/"+city) every 30s

(full version, with the HTML page and /health, in the repo's real file.)

requirements.txt — fastapi, uvicorn[standard], httpx, with pinned versions.

Delonixfile — a multi-stage build: one stage installs the Python dependencies, the other just copies the result plus the code — the final image carries no pip cache and no build tools:

FROM python:3.12-slim AS builder
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir --prefix=/install -r requirements.txt

FROM python:3.12-slim
WORKDIR /app
COPY --from=builder /install /usr/local
COPY main.py .
ENV PYTHONUNBUFFERED=1
CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "80"]

2. Build

cd examples/delonix-temp
delonix build -t delonix-temp:1 .

Collecting fastapi==0.115.0 (from -r requirements.txt (line 1))
...
Successfully installed annotated-types-0.7.0 anyio-4.14.2 ... fastapi-0.115.0 ...
ef708d73f029

The ID at the end (ef708d73f029) is the image. delonix image ls confirms the size — the final stage, with no build tools, ends up much smaller than if everything were in a single FROM:

delonix image ls

REPOSITORY:TAG     IMAGE ID       CREATED          SIZE
delonix-temp:1     ef708d73f029   just now         157.2 MiB
python:3.12-slim   25c5b8011a34   just now          41.2 MiB

3. Run it

delonix container run -d --name delonix-temp -p 8080:80 delonix-temp:1
curl -s http://localhost:8080/api/weather/Luanda

{"city":"Luanda","country":"Angola","temperature_c":20.2,"observed_at":"2026-07-23T19:00"}

A REAL temperature, looked up live — not a fixed value. The container's logs confirm the requests:

delonix container logs delonix-temp

INFO:     Uvicorn running on http://0.0.0.0:80 (Press CTRL+C to quit)
INFO:     10.0.2.2:57786 - "GET /health HTTP/1.1" 200 OK
INFO:     10.0.2.2:57802 - "GET /api/weather/Luanda HTTP/1.1" 200 OK

4. Expose it to the internet

A local port isn't enough — the goal is a URL anyone, on any network, can open. This is where kind: Gateway comes in:

delonix net tunnel expose 8080 --name delonix-temp

tunnel/delonix-temp: running — https://lfdhz-197-148-40-67.free.pinggy.net

That URL is REAL — it's the one this guide got when the command was actually run. (Yours will be different every time: the free provider assigns a new one each session.) Confirmation, from the outside, without touching anything local:

curl https://lfdhz-197-148-40-67.free.pinggy.net/api/weather/Luanda

{"city":"Luanda","country":"Angola","temperature_c":20.2,"observed_at":"2026-07-23T19:00"}

The same JSON, this time arriving from outside the machine, through an SSH tunnel to a public server (pinggy) and back — zero router configuration, zero public IP of your own, zero account. Opening the URL in a browser shows the Delonix Temp page updating itself.

Cleanup

delonix delete gateway delonix-temp
delonix container rm -f delonix-temp

What this proved