Adding websocket to flask with SocketIO

docker-compose.prod.yml

@@ -1,6 +1,6 @@
 services:
   db:
-    image: postgres:15.2
+    image: postgres:16.1
     container_name: db
     env_file:
       - .env

docker-compose.yml

@@ -1,6 +1,6 @@
 services:
   db:
-    image: postgres:15.2
+    image: postgres:16.1
     container_name: db
     env_file:
       - .env
@@ -16,30 +16,44 @@ services:
       timeout: 20s
       retries: 5
 
+  redis:
+    image: redis:7.2.3
+    container_name: redis
+    healthcheck:
+      test: ["CMD", "redis-cli", "ping"]
+      interval: 10s
+      timeout: 5s
+      retries: 3
+
   flask:
     build: ./flask
     container_name: flask
     env_file:
       - .env
+    ports:
+      - "5000:5000"
     depends_on:
+      # waiting for the upstream containers to be ready
+      redis:
+        condition: service_healthy
       db:
-        # waiting for the database to be ready
         condition: service_healthy
+
     volumes:
       - ./flask:/app
 
-  nginx:
-    image: nginx:latest
-    container_name: nginx
-    ports:
-      - "80:80"
-      - "443:443"
-    volumes:
-      - ./nginx/conf.d:/etc/nginx/conf.d
-      - ./nginx/nginx.conf:/etc/nginx/nginx.conf
-      - ./nginx/ssl-certs:/etc/nginx/ssl-certs
-    depends_on:
-      - flask
+  # nginx:
+  #   image: nginx:latest
+  #   container_name: nginx
+  #   ports:
+  #     - "80:80"
+  #     - "443:443"
+  #   volumes:
+  #     - ./nginx/conf.d:/etc/nginx/conf.d
+  #     - ./nginx/nginx.conf:/etc/nginx/nginx.conf
+  #     - ./nginx/ssl-certs:/etc/nginx/ssl-certs
+  #   depends_on:
+  #     - flask
 
 # to persist container volumes
 volumes:

flask/Dockerfile

@@ -18,4 +18,7 @@ USER flaskuser
 # CMD python application.py
 # CMD python application.py run --debug --host 0.0.0.0
 
-CMD gunicorn --access-logfile '-' --workers 2 --threads 3 --bind flask:5000 application:application
+# without Flask-SocketIO
+# CMD gunicorn --access-logfile '-' --workers 1 --threads 4 --bind flask:5000 application:application
+# with Flask-SocketIO
+CMD gunicorn --access-logfile '-' --worker-class eventlet --workers 1 --threads 4 --bind flask:5000 application:application

flask/app/__init__.py

@@ -1,9 +1,11 @@
 from flask import Flask
 from flask_sqlalchemy import SQLAlchemy
 from flask_cors import CORS
+from flask_socketio import SocketIO
 import os
 
 db = SQLAlchemy()
+socketio = SocketIO()
 
 def create_app():
 
@@ -20,8 +22,10 @@ def create_app():
         port=os.environ['RDS_PORT'],
         database=os.environ['RDS_DB_NAME'],
     )
+    app.config['SECRET_KEY'] = os.environ['SECRET_KEY']
 
     db.init_app(app)
+    socketio.init_app(app)
 
     # importing and registering routes with their url prefix
     from .views.main import main_bp

flask/app/views/__init__.py

@@ -0,0 +1 @@
+from . import sockets

flask/app/views/sockets.py

@@ -0,0 +1,15 @@
+from flask_socketio import emit, send
+from app import socketio
+
+@socketio.on('message')
+def handle_message(message):
+    print('Received message:', message)
+    emit('response', {'data': 'Server received your message'})
+
+@socketio.on('json')
+def handle_json(json):
+    print('received json: ' + str(json))
+
+@socketio.on('my event')
+def handle_my_custom_event(json):
+    print('received my_event: ' + str(json))

flask/requirements.txt

@@ -1,17 +1,26 @@
+bidict==0.22.1
 click==8.1.7
+dnspython==2.4.2
+eventlet==0.34.2
 Flask==2.2.3
 Flask-Cors==3.0.10
+Flask-SocketIO==5.3.6
 Flask-SQLAlchemy==3.0.3
 greenlet==2.0.2
 gunicorn==21.2.0
+h11==0.14.0
 importlib-metadata==7.0.1
 itsdangerous==2.1.2
 Jinja2==3.1.2
 MarkupSafe==2.1.3
 packaging==23.2
 psycopg2-binary==2.9.6
+python-engineio==4.8.2
+python-socketio==5.11.0
+simple-websocket==1.0.0
 six==1.16.0
 SQLAlchemy==2.0.9
 typing_extensions==4.9.0
 Werkzeug==2.2.3
+wsproto==1.2.0
 zipp==3.15.0

nginx/conf.d/server.conf

@@ -20,4 +20,4 @@ server {
         proxy_set_header X-Forwarded-Host $host;
         proxy_set_header X-Forwarded-Prefix /;
     }
-}
+}