How do I get Flask to run on port 80?
So it's throwing up that error message because you have
apache2 running on port 80.
If this is for development, I would just leave it as it is on port 5000.
If it's for production either:
Not recommended as it states in the documentation:
You can use the builtin server during development, but you should use a full deployment option for production applications. (Do not use the builtin development server in production.)
apache2 can handle all your static files (which it's very good at - much better than the debug server built into Flask) and act as a reverse proxy for your dynamic content, passing those requests to Flask.
Here's a link to the official documentation about setting up Flask with Apache + mod_wsgi.
Edit 1 - Clarification for @Djack
Proxy HTTP traffic to Flask through apache2
When a request comes to the server on port 80 (
HTTP) or port 443 (
HTTPS) a web server like Apache or Nginx handles the connection of the request and works out what to do with it. In our case a request received should be configured to be passed through to Flask on the WSGI protocol and handled by the Python code. This is the "dynamic" part.
reverse proxy for dynamic content
There are a few advantages to configuring your web server like the above;
- SSL Termination - The web server will be optimized to handle HTTPS requests with only a little configuration. Don't "roll your own" in Python which is probably very insecure in comparison.
- Security - Opening a port to the internet requires careful consideration of security. Flask's development server is not designed for this and could have open bugs or security issues in comparison to a web server designed for this purpose. Note that a badly configured web server can also be insecure!
- +more. This is bordering on scope for this question. If you want more info do some research into this area.