With OpenShift 4, Red Hat introduced Red Hat Enterprise Linux CoreOS. It is a very minimalistic operating system, focused on running container workload.
This new minimalism comes with some challenges. There are no more RPM packages and most of the tools we know and love are missing! Luckily, there is the Red Hat supplied
toolbox container that contains all the necessary tools and is nicely integrated.
So to start the toolbox, use
oc debug node/<nodename>. This will start a privileged container on the node you specify, mount the host filesystem on
/host and drop you into a shell:
$ oc debug node/worker-0.lab.openshift.krenger.ch
Starting pod/worker-0labopenshiftkrengerch-debug ...
To use host binaries, run `chroot /host`
If you don't see a command prompt, try pressing enter.
sh-4.2# chroot /host
Container started successfully. To exit, type 'exit'.
Now we are running in the
toolbox container on our CoreOS host with all the tools we know at our disposal, for example
sosreport will generate a sosreport in
/host/var/tmp/, which means it will be accessible in
/var/tmp/ on the CoreOS host itself.