FastAPIとPostgreSQLを日本のサーバーで公開する手順

requirements.txt   Pythonパッケージ
main.py            APIと起動処理
init_db.py         初回のテーブル作成
.gitignore         .envなどの除外

fastapi==0.128.8
uvicorn==0.39.0
psycopg[binary]==3.2.13

import hmac
import os
from typing import Optional

import psycopg
import uvicorn
from fastapi import Depends, FastAPI, Header, HTTPException
from pydantic import BaseModel, Field
from psycopg.rows import dict_row

app = FastAPI(title="Small Notes API")

def connection():
    # Context managers commit on success, roll back on error, and close.
    return psycopg.connect(os.environ["DATABASE_URL"], connect_timeout=5,
                           row_factory=dict_row)

def authorize(authorization: Optional[str] = Header(default=None)):
    token = os.environ.get("DEMO_API_TOKEN", "")
    if not token:
        raise HTTPException(status_code=503, detail="API token is not configured")
    expected = "Bearer " + token
    if not hmac.compare_digest((authorization or "").encode(), expected.encode()):
        raise HTTPException(status_code=401, detail="Authentication required")

class Note(BaseModel):
    body: str = Field(min_length=1, max_length=500)

@app.get("/healthz")
def health():
    return {"ok": True}

@app.get("/readyz", dependencies=[Depends(authorize)])
def ready():
    with connection() as conn:
        conn.execute("SELECT 1")
    return {"database": "ok"}

@app.get("/notes", dependencies=[Depends(authorize)])
def list_notes():
    with connection() as conn:
        return conn.execute("SELECT id, body FROM notes ORDER BY id DESC LIMIT 50").fetchall()

@app.post("/notes", status_code=201, dependencies=[Depends(authorize)])
def create_note(note: Note):
    with connection() as conn:
        return conn.execute("INSERT INTO notes (body) VALUES (%s) RETURNING id, body",
                            (note.body,)).fetchone()

if __name__ == "__main__":
    uvicorn.run("main:app", host="0.0.0.0", port=int(os.getenv("PORT", "8000")))

from main import connection

with connection() as conn:
    conn.execute("""
        CREATE TABLE IF NOT EXISTS notes (
            id bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
            body text NOT NULL CHECK (length(body) BETWEEN 1 AND 500)
        )
    """)
print("notes table is ready")

python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

export DATABASE_URL='postgresql://demo_user:local_password@127.0.0.1:5432/notes_demo'
export DEMO_API_TOKEN='local-demo-only-change-before-publication'
python init_db.py
python main.py

curl --fail http://127.0.0.1:8000/healthz

curl --fail http://127.0.0.1:8000/readyz \
  -H "Authorization: Bearer $DEMO_API_TOKEN"

curl --fail http://127.0.0.1:8000/notes \
  -H "Authorization: Bearer $DEMO_API_TOKEN" \
  -H 'Content-Type: application/json' \
  -d '{"body":"最初の保存テスト"}'

curl --fail http://127.0.0.1:8000/notes \
  -H "Authorization: Bearer $DEMO_API_TOKEN"