mariaDB docker container inside LXD isn't accessible from the host OS

LXD
1

Hello everyone.
I have an LXD container and i have installed docker inside the LXD container as described here
(Running Docker inside of a LXD container - YouTube)
Inside the LXD container i have deployED a mariaDB instance from the offical docker repo.
I ran the docker container with the -p option in order for the docker container to be accessible from processes outside the LXD container.

I have a python script at the host OS which tries to connect to the mariaDB container but i receive:

ERROR:root:2003 (HY000): Can’t connect to MySQL server on ‘10.35.66.110:3306’ (111)

which indicates that the network connection has been refused.

I ran tcpdump inside the LXD container and the traffic arrives normally at port 3306 which is the mariadb’s default port.

ip a gives the following:

root@batterystation:/home/ubuntu# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:3e:06:dd:5a brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:3eff:fe06:dd5a/64 scope link 
       valid_lft forever preferred_lft forever
8: eth0@if9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 00:16:3e:bd:6d:3a brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 10.35.66.110/24 brd 10.35.66.255 scope global dynamic eth0
       valid_lft 2628sec preferred_lft 2628sec
    inet6 fe80::216:3eff:febd:6d3a/64 scope link 
       valid_lft forever preferred_lft forever

while ip r gives

root@batterystation:/home/ubuntu# ip r
default via 10.35.66.1 dev eth0 proto dhcp src 10.35.66.110 metric 100 
10.35.66.0/24 dev eth0 proto kernel scope link src 10.35.66.110 
10.35.66.1 dev eth0 proto dhcp scope link src 10.35.66.110 metric 100 
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown

Any help ?

2

I tried the examaple with the nextcloud docker container inside the demo lxd container and worked fine by the way.

I find this → LXD , docker , mariadb/mysql - #5 by benoit.georgelin

So it means we hit a wall, right ?

3

No XP - I might be wrong - tried adding a proxy device / making sure mariadb listens on every interface?

I cant imagine docker mariadb listens on every network interface by default, most DB dont these days…

4

@turtle0x1

It does actually

root@batterystation:/# docker ps
CONTAINER ID   IMAGE        COMMAND                  CREATED          STATUS         PORTS                                       NAMES
c36722cca4a8   bsdb_image   "docker-entrypoint.s…"   10 seconds ago   Up 4 seconds   0.0.0.0:3306->3306/tcp, :::3306->3306/tcp   bsdb

The bsdb_image isn’t something special. It is the official mariadb image plus a .sql configuration which just simple create some tables

5

Hi @tkasidakis ,
I have tested an example and reached mariadb server from host my machine, here are my steps.

lxc launch images:ubuntu/22.04/cloud test
lxc config set test security.nesting=true
lxc shell test
apt install curl
curl -ssl https://get.docker.com/ | sh
systemctl start docker
docker run --name mariatest -p 3306:3306 -e MYSQL_ROOT_PASSWORD=123qwe -d mariadb

At the host side, installed the apt install mariadb-client-core-10.6 maria client.
And connect with the following statement.

mariadb --host 10.240.176.198 --user root -p123qwe

Here is my network structure.

+-----------+---------+-----------------------+-----------------------------------------------+-----------+-----------+
| test      | RUNNING | 172.17.0.1 (docker0)  | fd42:e8f7:40f5:2333:216:3eff:fe43:b9ad (eth0) | CONTAINER | 0         |
|           |         | 10.240.176.198 (eth0) |                                               |           |           |
+-----------+---------+-----------------------+-----------------------------------------------+-----------+-----------+

Regards.

6

Thanks a lot for the answer @cemzafer .

I figure out what’s the problem. I had forgotten to set the -e parameter MARIADB_DATABASE when i was starting the docker container :slight_smile: . The fact that I was starting the mariadb container with -d ( detach mode) was preventing me from seeing the logs of the docker container and figure out the solution.

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