Weird MySQL Python mod_wsgi Can't connect to MySQL server on 'localhost' (49) problem

问题

There have been similar questions on StackOverflow about this, but I haven't found quite the same situation. This is on a OS X Leopard machine using MySQL

Some starting information:

MySQL Server version        5.1.30
Apache/2.2.13 (Unix)
Python 2.5.1
mod_wsgi 3

mysqladmin also has skip-networking listed as OFF

I am able to connect to mysql from the python command line. But when I try to do it through mod_wsgi using code that is copy and pasted or via Django I receive the generic connection refusal

OperationalError: (2003, "Can't connect to MySQL server on 'localhost' (49)")

I've looked at the mysql manual and tried its troubleshooting tips such as

telnet localhost 3306

and I do get a connection.

I am not trying to connect as root, either.

Any ideas on what else I could check? Thanks in advance!

回答1:

I came across this error and it was due to an SELinux denial. /usr/bin/httpd didn't have permission to connect to port 3306. I corrected the issue with:

setsebool httpd_can_network_connect_db on

Seems to work great and should be more secure than just disabling SELinux. As Avinash Meetoo points out below, you can use:

setsebool -P httpd_can_network_connect_db

To make the selinux change persist across reboots.

回答2:

I was getting the exact same error message in Django:

OperationalError: (2003, "Can't connect to MySQL server on 'localhost' (49)")

To fix it, I had to explicitly set the mysql port to 3306 in the django settings file.

回答3:

Not too much out there on this. Just a random guess but try using:

DATABASE_HOST = 'localhost' instead of 127.0.0.1

and/or try commenting out in your my.ini:

bind-address 127.0.0.1

worth a shot.

回答4:

Bit odd that the telnet connection works. Maybe some more ways to trouble shot:

shell> perror 49
OS error code  49:  Can't assign requested address

I would check the localhost interface first, check if it has IPv4 address. Far fetched maybe, but I had troubles ones when I didabled IPv6.

shell> ifconfig lo0

Maybe the name resolution doesn't work correctly from within Apache/mod_wsgi/etc..

import python
print socket.gethostbyname('localhost')
print socket.gethostbyaddr('127.0.0.1')

Maybe to get you going (something I contributed to Django) try the UNIX Socket in Django, it works setting the database host to the path (start with forward-slash):