Docker. OSX connect to the host from container (xdebug, mysql).

1. I use Docker for Mac 1.12.1 and wasn't able connect to the host from within container by gateway ip:

# docker exec -it my_container bash
root@container:/# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         172.19.0.1      0.0.0.0         UG    0      0        0 eth0
172.19.0.0      *               255.255.0.0     U     0      0        0 eth0
# mysql -uroot -p -h172.19.0.1
Enter password:
ERROR 2003 (HY000): Can't connect to MySQL server on '172.19.0.1' (111)

The only solution I found was create an alias to local network interface:

# sudo ifconfig lo0 alias 10.254.254.254
# ifconfig
lo0: flags=8049 mtu 16384
 options=1203
 inet 127.0.0.1 netmask 0xff000000
 inet6 ::1 prefixlen 128
 inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
 inet 10.254.254.254 netmask 0xff000000
 nd6 options=201
...

2. The next step is grant access to the db for user on binded ip

# mysql -uroot -p
...
mysql> GRANT ALL ON *.* TO 'root'@'%' IDENTIFIED BY '';

3. Next we need bind mysql address to 0.0.0.0 (any ip), so open /etc/my.cnf and add or edit string:

bind-address=0.0.0.0

restart server
4. You should be able to connect to you host db from within the container now:

# docker exec -it my_container bash
# mysql -uroot -p -h10.254.254.254
...
mysql>

yep!