Docker - No route to host

Question

When i try and connect to a port from within my container to another container, i am unsuccessful and get,

root@ac1590a59fe5:/opt/f5massupgrade#         


        

Answer 1

If anyone is still stuck with this problem on CentOS 8 or any system using firewalld

try the following settings for firewalld

# Allows container to container communication, the solution to the problem
firewall-cmd --zone=public --add-masquerade --permanent

# standard http & https stuff
firewall-cmd --zone=public --add-port=80/tcp --permanent
firewall-cmd --zone=public --add-port=443/tcp --permanent
# + any other port you may need

# reload the firewall
firewall-cmd --reload

you may also need to restart the docker service if it does not work immediately, there's no need to add the docker0 interface onto the trusted zone as many of the guides I've gone through stated

I was struggling with setting up a Traefik reverse proxy for my docker containers, I only got 502 responses with a no route error to my container from Traefik logs. At first I thought it was my Traefik setup but it turned out it was the firewall restrictions as @al. mentioned. It pointed me in the right direction and I got my answer from https://serverfault.com/questions/987686/no-network-connectivity-to-from-docker-ce-container-on-centos-8