RedHat4/Docker on Centos 7. Can't reach internet from Docker Instance

Question

From within my Docker instance (running Red Hat 4), I'm not able to reach the internet. Pinging Google:

 ping google.com
  ]ping: unknown host google.com

I am able to ping the endpoint on my host (Centos 7). Both container and host have the same DNS. Also on my Centos 7 host, I have Selinux disabled along with Firewalld.

Answer 1

If you inspect the container that is running you should be able to locate the resolv.conf file. Make sure the file is setup with a nameserver. For example:

docker ps

docker inspect 4fe7454659eb|grep -i resolv "ResolvConfPath": "/mnt/sda1/var/lib/docker/containers/4fe7454659eb203f94772f5da1f0c53dc45b2b8e9c71049e039621430cbd0775/resolv.conf",

Once you have the path connect to the running docker container

docker exec -it 4fe7454659eb bash

Then look into the listed directory from above.

cd /mnt/sda1/var/lib/docker/containers/4fe7454659eb203f94772f5da1f0c53dc45b2b8e9c71049e039621430cbd0775/

The resolv.conf file should contain a nameserver. If not, then add one. You will have to save the state of the image after you change the resolv.conf file by committing it. Mine has this:

cat resolv.conf nameserver 10.0.2.3