nginx + uWSGI + Flask が起動しない

Question

EC2(Amazon Linux)にて、nginx + uWSGI でFlaskを動かしたいと考えております。

ここまで行ったこと
■Nginxのインストール
■uWSGIのインストール
（ここまで　Nginx + uWSGI + Flaskによるwebアプリの構築　の3.1.2 と3.1.4を参考。Pythonは仮想環境ではなくEC2にもともと入っているものを使用しています。そのためpip はpip3 のようにして打ちました。）

■アプリのディレクトリの作成
起動するアプリは
|-templates
|-app.py
|-requirements.txt

といった構成です。これを/var 下に　/www/uwsgi　を作成し、配置しました。

■socket通信用のディレクトリを作成
[第一部]これならわかる！Flask+Nginx+uWSGIをAWSに丁寧にデプロイ
こちらのディレクトリ名を参考に、uwsgi 下に run ディレクトリを作成しました。

■app.iniファイルの作成
Nginx + uWSGI + Flaskによるwebアプリの構築 の3.2を参考に、app.iniを作成しました。

[uwsgi]
module = app
callable = app
master = true
processes = 1
socket = /var/run/uwsgi.sock
chmod-socket = 666
vacuum = true
die-on-term = true
wsgi-file = /var/www/uwsgi/app.py
logto = /var/www/uwsgi/app.log
http = 0.0.0.0:80

空のログファイルを合わせ、以下のような構成になっています。

/var/www/uwsgi/
|-app.py
|-app.ini
|-app.log
|-templates
|-run
|-requirements.txt

■WSGIとNginxの連携
Nginx + uWSGI + Flaskによるwebアプリの構築 の3.3を参考に、以下のnxinxのconfファイルを作成しました。

sudo vi /etc/nginx/conf.d/uwsgi.conf

server {
    listen       80;

    location / {
        include uwsgi_params;
        uwsgi_pass unix:///var/run/uwsgi.sock;
    }
}

以上です。これで、以下はできています。

□ pythonで直で実行

python3 app.py

$ python3 app.py
 * Serving Flask app 'app' (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: on
 * Running on http://127.0.0.1:5000 (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 287-234-209

□uWSGIで実行

uwsgi --http=0.0.0.0:5000 --wsgi-file=app.py --callable=app

$ uwsgi --http=0.0.0.0:5000 --wsgi-file=app.py --callable=app
*** Starting uWSGI 2.0.20 (64bit) on [Fri Jun 17 16:10:01 2022] ***
compiled with version: 7.3.1 20180712 (Red Hat 7.3.1-15) on 17 June 2022 08:56:32
os: Linux-X.XX.XXX-XXX.XXX.amzn2.x86_64 #1 SMP Wed May 25 22:12:19 UTC 2022
nodename: ip-10-0-1-162.ap-northeast-1.compute.internal
machine: x86_64
clock source: unix
detected number of CPU cores: 1
current working directory: /var/www/uwsgi
detected binary path: /home/ec2-user/.local/bin/uwsgi
!!! no internal routing support, rebuild with pcre support !!!
*** WARNING: you are running uWSGI without its master process manager ***
your memory page size is 4096 bytes
detected max file descriptor number: 65535
lock engine: pthread robust mutexes
thunder lock: disabled (you can enable it with --thunder-lock)
uWSGI http bound on 0.0.0.0:5000 fd 4
spawned uWSGI http 1 (pid: 21006)
uwsgi socket 0 bound to TCP address 127.0.0.1:45927 (port auto-assigned) fd 3
Python version: 3.7.10 (default, Jun  3 2021, 00:02:01)  [GCC 7.3.1 20180712 (Red Hat 7.3.1-13)]
*** Python threads support is disabled. You can enable it with --enable-threads ***
Python main interpreter initialized at 0x2470f60
your server socket listen backlog is limited to 100 connections
your mercy for graceful operations on workers is 60 seconds
mapped 72904 bytes (71 KB) for 1 cores
*** Operational MODE: single process ***
unable to find "application" callable in file app.py
unable to load app 0 (mountpoint='') (callable not found or import error)
*** no app loaded. going in full dynamic mode ***
*** uWSGI is running in multiple interpreter mode ***
spawned uWSGI worker 1 (and the only) (pid: 21005, cores: 1)

しかし、uwsgiコマンドでiniを渡して動かそうとすると、すぐに止まって、エラーログがapp.logに残ります。
□nginx + uWSGIで実行

$ uwsgi --ini /var/www/uwsgi/app.ini

$ uwsgi --ini /var/www/uwsgi/app.ini
[uWSGI] getting INI configuration from /var/www/uwsgi/app.ini

こちらの状態で、4000番ポートにアクセスすると見えるものの、nginxと連携できているようには見えません。
ctrl+Cで終了した後、app.logを確認すると以下のように残ります。

$ cat app.log
*** Starting uWSGI 2.0.20 (64bit) on [Fri Jun 17 17:04:38 2022] ***
compiled with version: 7.3.1 20180712 (Red Hat 7.3.1-15) on 17 June 2022 08:56:32
os: Linux-X.XX.XXX-XXX.XXX.amzn2.x86_64 #1 SMP Wed May 25 22:12:19 UTC 2022
nodename: ip-10-0-1-162.ap-northeast-1.compute.internal
machine: x86_64
clock source: unix
detected number of CPU cores: 1
current working directory: /var/www/uwsgi
detected binary path: /home/ec2-user/.local/bin/uwsgi
!!! no internal routing support, rebuild with pcre support !!!
chdir() to /var/www/uwsgi
your memory page size is 4096 bytes
detected max file descriptor number: 65535
lock engine: pthread robust mutexes
thunder lock: disabled (you can enable it with --thunder-lock)
uWSGI http bound on 0.0.0.0:4000 fd 3
uwsgi socket 0 bound to UNIX address /tmp/uwsgi.sock fd 6
Python version: 3.7.10 (default, Jun  3 2021, 00:02:01)  [GCC 7.3.1 20180712 (Red Hat 7.3.1-13)]
*** Python threads support is disabled. You can enable it with --enable-threads ***
Python main interpreter initialized at 0x147d350
your server socket listen backlog is limited to 100 connections
your mercy for graceful operations on workers is 60 seconds
mapped 145808 bytes (142 KB) for 1 cores
*** Operational MODE: single process ***
WSGI app 0 (mountpoint='') ready in 0 seconds on interpreter 0x147d350 pid: 21379 (default app)
mountpoint  already configured. skip.
*** uWSGI is running in multiple interpreter mode ***
spawned uWSGI master process (pid: 21379)
spawned uWSGI worker 1 (pid: 21382, cores: 1)
spawned uWSGI http 1 (pid: 21383)
SIGINT/SIGTERM received...killing workers...
gateway "uWSGI http 1" has been buried (pid: 21383)
worker 1 buried after 1 seconds
goodbye to uWSGI.
VACUUM: unix socket /tmp/uwsgi.sock removed.

権限の問題に見えますが、解決できておりません。