【Docker × Flask】FlaskAPIをGunicornのカスタムアプリケーションで起動する

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.
|-- Dockerfile
|-- app
|   |-- __init__.py
|   |-- __main__.py
|   `-- app.py
|-- config
|   `-- cfg.ini
|-- docker-compose.yml
`-- vscode_ex_install.sh

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FROM python:3.12

# workspaceディレクトリ作成、移動
WORKDIR /workspace

# プロジェクトディレクトリにコピー
COPY requirements.txt /workspace

# 必要モジュールのインストール
RUN pip install --upgrade pip
RUN pip install -r requirements.txt

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version: "3"
services:
  sample-api:
    container_name: "flask_gunicorn"
    build:
      context: .
      dockerfile: Dockerfile

    ports:
      - "5000:5000"
    volumes:
      # バインドマウント
      - .:/workspace
    tty: true

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Flask==3.0.2
gunicorn==21.2.0

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$ docker compose up -d
$ docker ps
CONTAINER ID   IMAGE                       COMMAND     CREATED          STATUS          PORTS                    NAMES
242a4af01ee2   flask-gunicorn-sample-api   "python3"   42 seconds ago   Up 38 seconds   0.0.0.0:5000->5000/tcp   flask_gunicorn

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[gunicorn]
bind = 0.0.0.0:5000
workers = 1
loglevel = info
; errorlog = /var/log/error.log
errorlog = -
accesslog = /var/log/access.log

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from configparser import ConfigParser
from gunicorn.app.base import BaseApplication

from app.app import flaskapp

class AppConfig:
    @staticmethod
    def load_config(path):
        # 設定ファイルからGunicornの設定取得
        config = ConfigParser()
        config.read(path)
        options = dict(config.items('gunicorn'))
        return options

class CustumApplication(BaseApplication):
    def __init__(self,app,options=None):
        self.options = options or {}
        self.application = app
        super().__init__()     

    # Gunicornの設定をロードする
    def load_config(self):
        for key, value in self.options.items():
            self.cfg.set(key.lower(), value)

    # Gunicornがサーブするアプリケーションインスタンスをロードする
    def load(self):
        return self.application

if __name__ == '__main__':
    # 設定ファイル読み込み
    options = AppConfig.load_config('./config/cfg.ini')

    # gunicornでアプリケーション起動
    CustumApplication(flaskapp, options).run()

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from flask import Flask

# flaskインスタンス作成
flaskapp = Flask(__name__)

# ディクショナリ
users = [
    {"user_id": "1", "name": "tujimura", "age": 11},
    {"user_id": "2", "name": "mori", "age": 20},
    {"user_id": "3", "name": "shimada", "age": 50},
    {"user_id": "4", "name": "kyogoku", "age": 70}]

@flaskapp.route('/', methods=['GET'])
def get_users():
    # GETリクエストを処理
    return users

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root@242a4af01ee2:/workspace# python -m app
[2024-06-12 07:16:05 +0000] [23654] [INFO] Starting gunicorn 21.2.0
[2024-06-12 07:16:05 +0000] [23654] [INFO] Listening at: http://0.0.0.0:5000 (23654)
[2024-06-12 07:16:05 +0000] [23654] [INFO] Using worker: sync
[2024-06-12 07:16:05 +0000] [23704] [INFO] Booting worker with pid: 23704

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{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Module",
            "type": "debugpy",
            "request": "launch",
            "module": "app",
            "console": "integratedTerminal",
            "args": [],
            "justMyCode": false,
            "cwd": "${workspaceFolder}"
        }
    ]
}