Rails6 Action CableをNginx & PostgreSQLの本番環境で使用する設定方法

# config/routes.rb

mount ActionCable.server => '/cable' # この記載は不要

# config/cable.yml

production:
  adapter: postgresql
# url: <%= ENV.fetch("REDIS_URL") { "redis://localhost:6379/1" } %>
# channel_prefix: xxxx_production

# config/environments/production.rb

# Mount Action Cable outside main process or domain.
# config.action_cable.mount_path = nil
# config.action_cable.url = 'wss://example.com/cable'
# config.action_cable.allowed_request_origins = [ 'http://example.com', /http:\/\/example.*/ ]
config.action_cable.allowed_request_origins = [ 'http://example.com',
                                                /http:\/\/example.*/,
                                                'https://example.com',
                                                /https:\/\/example.*/ ]

# xxxx.conf

upstream unicorn_アプリケーション名 {
  server unix:/var/www/アプリケーション名/current/tmp/sockets/unicorn.sock;
}
server {
  listen 443;
  ssl on;
  server_name example.com;
  root /var/www/アプリケーション名/current/public;
  access_log /var/log/nginx/アプリケーション名_access.log;
  error_log /var/log/nginx/アプリケーション名_error.log;
  ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
  ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot
  include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
  ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
  location / {
    try_files $uri @unicorn;
  }
  location @unicorn {
    proxy_set_header Host $http_host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_pass http://unicorn_アプリケーション名;
  }
  location /cable {
    proxy_http_version 1.1;
    proxy_set_header Upgrade websocket;
    proxy_set_header Connection Upgrade;
    proxy_set_header Host $http_host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_pass http://unicorn_アプリケーション名;
  }
}