main.py

import os, json
from fastapi import FastAPI
import psycopg2
import redis

PG_HOST = os.getenv("PG_HOST", "pg-rw")
PG_DB   = os.getenv("PG_DB", "appdb")
PG_USER = os.getenv("PG_USER", "appuser")
PG_PASS = os.getenv("PG_PASS", "apppass")

REDIS_HOST = os.getenv("REDIS_HOST", "dragonfly")
REDIS_PORT = int(os.getenv("REDIS_PORT", "6379"))

CACHE_KEY = "todos:all"

app = FastAPI()
r = redis.Redis(host=REDIS_HOST, port=REDIS_PORT, decode_responses=True)

def pg_conn():
    return psycopg2.connect(
        host=PG_HOST, dbname=PG_DB, user=PG_USER, password=PG_PASS
    )

@app.on_event("startup")
def init_db():
    with pg_conn() as conn:
        with conn.cursor() as cur:
            cur.execute("""
              CREATE TABLE IF NOT EXISTS todos (
                id SERIAL PRIMARY KEY,
                title TEXT NOT NULL
              );
            """)
        conn.commit()

@app.get("/todos")
def list_todos():
    cached = r.get(CACHE_KEY)
    if cached:
        return {"source": "cache(dragonfly)", "items": json.loads(cached)}

    with pg_conn() as conn:
        with conn.cursor() as cur:
            cur.execute("SELECT id, title FROM todos ORDER BY id DESC;")
            rows = cur.fetchall()

    items = [{"id": i, "title": t} for (i, t) in rows]
    r.set(CACHE_KEY, json.dumps(items), ex=30)  # 30s TTL
    return {"source": "db(postgres)", "items": items}

@app.post("/todos")
def add_todo(payload: dict):
    title = payload.get("title", "").strip()
    if not title:
        return {"ok": False, "error": "title is required"}

    with pg_conn() as conn:
        with conn.cursor() as cur:
            cur.execute("INSERT INTO todos (title) VALUES (%s) RETURNING id;", (title,))
            new_id = cur.fetchone()[0]
        conn.commit()

    r.delete(CACHE_KEY)  # invalidate cache
    return {"ok": True, "id": new_id, "title": title}