Containers are good, no matter you are using native Kubernetes cluster or using OpenShift, but when it comes troubleshoot, it can be quite frustrating as most time the container doesn't have the toolset you normally use for test and information collection.

To resolved that, you could build a troubleshooting image with all tools your company use loaded, inject the container as a side-cart when you need them, this works great but its not something I want to talk about.

The use case here is quite simple, I don't have telnet, nc, ss, netstat or whaever installed in my container, how can i confirm connection is there....

The answer is quite simple, you can use build in bash command to test any tcp connection from your container to somewhere else.

For example, i want to test if my container be able to connect to my database server mypostgres

You can simply run following command in your container

timeout 1 bash -c "cat < /dev/null > /dev/tcp/mypostgres/5432"
echo $?

If $? returns 0, then you know your container can talk to the remote whatever endpoint, else, your container doesn't have connectivity to the remote endpoint