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I have a simple Python based web server running in a container set up with docker compose that exposes port 8080.

When I docker-compose up the services it reports the ports are exposed but the port is not exposed externally.

What should I look at diagnosing next?

Here's a typical run

➜  demo04 sudo docker-compose up -d
Recreating leagueweb_database ... done
Recreating leagueweb_server   ... done

The Python web server (using CherryPy) reports it has started OK and opened port 8080.

leagueweb_server | [25/Jan/2022:11:27:21] ENGINE Serving on http://127.0.0.1:8080

Docker reports that it is forwarding port 8080

➜  demo04 sudo docker-compose ps
       Name                     Command                  State                              Ports
------------------------------------------------------------------------------------------------------------------------
leagueweb_database   /entrypoint.sh mysqld            Up (healthy)   0.0.0.0:3306->3306/tcp,:::3306->3306/tcp, 33060/tcp
leagueweb_server     ./wait-for-it.sh database: ...   Up             0.0.0.0:8080->8080/tcp,:::8080->8080/tcp

Testing this from a remote PC I can see that although port 3306 is open externally - port 8080 is not.

PS C:> Test-NetConnection 192.168.1.132 -Port 3306
RemoteAddress    : 192.168.1.132
RemotePort       : 3306
TcpTestSucceeded : True

PS C:> Test-NetConnection 192.168.1.132 -Port 8080
WARNING: TCP connect to (192.168.1.132 : 8080) failed

The firewall is turned off

➜  demo04 sudo ufw status
Status: inactive

This is the docker compose file

version: '3'
services:

    leagueweb:
        # Install Python and required libraries with a Dockerfile
        build:
            context: .
            dockerfile: leagueweb.dockerfile
            
        restart: unless-stopped
        
        container_name: leagueweb_server
        
        # Don't start up until the database is started
        depends_on:
            - database
        
        # Expose HTTP port 
        ports:
            - "8080:8080"

        # Mount the leagueweb code and resources
        volumes:
            - "/home/testuser/demo04/code:/leagueweb"
 
        # Start the server only once the database is running
        command: ["./wait-for-it.sh", "database:3306", "--", "python", "-u", "/leagueweb/leagueweb.py"]
        

    database:
        # Use MySQL 5.7 as the database
        image: mysql/mysql-server:5.7
        
        restart: unless-stopped
        
        container_name: leagueweb_database

        # Set environment variables to set initial database set-up
        environment:
            - "MYSQL_ROOT_PASSWORD=root"
            - "MYSQL_USER=leagueweb"
            - "MYSQL_PASSWORD=********"
            - "MYSQL_DATABASE=leagueweb01"
            
        # Uncomment to expose the MySQL database externally on port 3306 for 
        # testing 
        ports:
            - "3306:3306"

        # Mount init.sql file to automatically run and create tables for us.
        # everything in docker-entrypoint-initdb.d folder is executed as 
        # soon as container is up and running.
        volumes:
            - "/home/testuser/demo04/db:/docker-entrypoint-initdb.d"

1 Answer 1

3

This looks like a problem:

ENGINE Serving on http://127.0.0.1:8080

Looks like you need to reconfigure your python server to listen on 0.0.0.0, not 127.0.0.1

2
  • Thanks. Can't believe I didn't see that - it was starting me in the face. Looks like I had got too focused on thinking it was a container issue.
    – evoelise
    Jan 25 at 15:00
  • Happens to us all!
    – shearn89
    Jan 25 at 15:13

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