I'm using docker containers to host a web app. I have three main containers: MySQL, flask and Nginx. The first two work as expected and the latter seems to be working fine as no error is displayed in the docker-compose startup.

Nginx container initialization output:

nginx  | /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
nginx  | /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
nginx  | /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
nginx  | 10-listen-on-ipv6-by-default.sh: info: /etc/nginx/conf.d/default.conf is not a file or does not exist
nginx  | /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
nginx  | /docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
nginx  | /docker-entrypoint.sh: Configuration complete; ready for start up
nginx  | 2022/04/07 13:09:13 [notice] 1#1: using the "epoll" event method
nginx  | 2022/04/07 13:09:13 [notice] 1#1: nginx/1.21.6
nginx  | 2022/04/07 13:09:13 [notice] 1#1: built by gcc 10.2.1 20210110 (Debian 10.2.1-6) 
nginx  | 2022/04/07 13:09:13 [notice] 1#1: OS: Linux 4.19.130-boot2docker
nginx  | 2022/04/07 13:09:13 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
nginx  | 2022/04/07 13:09:13 [notice] 1#1: start worker processes
nginx  | 2022/04/07 13:09:13 [notice] 1#1: start worker process 21

Nginx dockerfile

# Dockerfile-nginx
FROM nginx:latest
# Nginx will listen on this port
# EXPOSE 80
# Remove the default config file that
# /etc/nginx/nginx.conf includes
RUN rm /etc/nginx/conf.d/default.conf
# We copy the requirements file in order to install
# Python dependencies
COPY nginx.conf /etc/nginx/conf.d/

Containers after being deployed and their respective ports:

CONTAINER ID   IMAGE             COMMAND                  CREATED          STATUS                 PORTS                               NAMES
bffffcfe2f70   sc_server_nginx   "/docker-entrypoint.…"   14 seconds ago   Up 13 seconds          0.0.0.0:80->80/tcp                  nginx
a73d958c1407   sc_server_flask   "uwsgi app.ini"          9 hours ago      Up 9 hours             8080/tcp                            flask
d273db5f80ef   mysql:5.7         "docker-entrypoint.s…"   21 hours ago     Up 9 hours (healthy)   0.0.0.0:3306->3306/tcp, 33060/tcp   mysql

I'm new to Nginx server, so I guess it may be a newbie error. I'm trying to redirect all the traffic from my host machine's 80 port to docker's 80 which redirects the traffic to the WSGI container via a socket.

I'm using the following Nginx configuration (nothing close to fancy I guess):

server {
  listen 80;
  location / {
    include uwsgi_params;
    uwsgi_pass flask:8080;
  }
}

As you can see the server listens at port 80 and redirects all the traffic via the socket uwsgi_pass flask:8080; to the WSGI container that is hosting the app.

However, whenever I type 127.0.0.1:80 or 0.0.0.0:80 in my browser the connection is refused. I have no firewall deployed, so I guess that there is no problem with port 80 being down.

This is my app.ini configuation file, in which the initialization and deployment params are indicated:

[uwsgi]
wsgi-file = wsgi.py
; This is the name of the variable
; in our script that will be called
callable = app
; We use the port 8080 which we will
; then expose on our Dockerfile
socket = :8080
; Set uWSGI to start up 4 workers
processes = 4
threads = 2
master = true
chmod-socket = 660
vacuum = true
die-on-term = true

Additionally, I also include the docker-compose.yml (I guess it may be helpful):

docker-compose.yml

services:
  flask:
    build: ./flask
    container_name: flask
    restart: always
    environment:
      - APP_NAME=MyFlaskApp
      - YOURAPPLICATION_SETTINGS=docker_config.py
    expose:
      - 8080
    depends_on:
      mysql:
          condition: service_healthy
  mysql:
    image: mysql:5.7
    container_name: mysql
    ports:
      - "3306:3306"
    environment:
      MYSQL_ROOT_PASSWORD:
      MYSQL_DATABASE:
      MYSQL_USER:
      MYSQL_PASSWORD:
    volumes:
      - ./db/init.sql:/data/application/init.sql
    healthcheck:
      test: mysql -u -p --database -e "show tables;"
      interval: 3s
      retries: 5
      start_period: 30s
  nginx:
    build: ./nginx
    container_name: nginx
    restart: always
    depends_on:
      - mysql
      - flask
    ports:
      - "80:80"

Anyone can help?

Update

I've used Wireshark to scan the loopback interface to see the server's response to 0.0.0.0:80 (I suspect there might be some problem with port 80) and I get the following payload:

Update 2:

After deploying the app in EC2 everything seems to be working fine. Thus, it has to be some problem with port 80 at localhost. My machine's OS is macOS Monterrey 12.4 and the system firewall is turned down.