Install ping tools (for diagnostics)

Ping is an utility to see if another host is reachable.
In some cases, dockers can be isolated and it can be daunting to try to understand who can see whom.

Using ping can help diagnosing some problems

Log into the docker (see interactive-shell-commandline )

And execute the following commands, so you can "ping"

apt-get update -y
apt-get install -y iputils-ping