Pfthb

I am transitioning my webserver and db into docker containers and using docker-compose to fire them up but encountering an issue. My container starts successfully, however, I have functions that pings other servers by hostname in my private network and that doesn't seem to work anymore when inside a docker container. For example:

ping other_hostname (cannot reach hostname inside container)

when I'm outside the container and ping other_hostname it works fine.

I did notice that when inside the container if I qualify the hostname like this:

ping other_hostname.home.com (this works inside the container)

Is there a way to ping by hostname when inside the container?

mount:

...

/dev/sdb3 on /etc/resolv.conf type btrfs (rw,relatime,space_cache,subvolid=258,subvol=/@/var/lib/docker/containers/13cfa734b33cda82a5e487d5a2a4b9aad2fdefaf844b49a4f92c99c4fd2089b8/resolv.conf)
/dev/sdb3 on /etc/hostname type btrfs (rw,relatime,space_cache,subvolid=258,subvol=/@/var/lib/docker/containers/13cfa734b33cda82a5e487d5a2a4b9aad2fdefaf844b49a4f92c99c4fd2089b8/hostname)
/dev/sdb3 on /etc/hosts type btrfs (rw,relatime,space_cache,subvolid=258,subvol=/@/var/lib/docker/containers/13cfa734b33cda82a5e487d5a2a4b9aad2fdefaf844b49a4f92c99c4fd2089b8/hosts)

...

resolve.conf:

~ $ cat /etc/resolv.conf
search mydomain.com
nameserver 127.0.0.11
options ndots:0

If you have a docker-compose.yml example like below you can access the different services by their name. Docker will treat them as their dns name.

So in the case below it would be mysql-service and gogs-service

version: '3'

services:
 mysql-service:
 image: mysql
 volumes:
 - ./setup:/docker-entrypoint-initdb.d
 - mysql-data:/var/lib/mysql
 ports:
 - "3306:3306"
 environment:
 - MYSQL_ROOT_PASSWORD=secret

 gogs-service:
 image: gogs
 volumes:
 - gogs-data:/data
 links:
 - mysql:mysql
 ports:
 - "10022:22"
 - "10000:3000"

volumes:
 mysql-data:
 driver: local
 gogs-data:
 driver: local

hope it helps :-)

Add your local dns server to docker container /etc/resolv.conf file as

nameserver dns_server_ip

then restart docker container.