Debugging with Toolbx
The FCOS image is kept minimal by design to reduce the image size and the attack surface. This means that it does not include every troubleshooting tool that a normal OS may include. Instead, the recommended approach is to leverage containers with the toolbox utility included in the image.
What is Toolbx?
Toolbx is a utility that allows you to create privileged containers meant to debug and troubleshoot your instance. It is a wrapper around podman which starts long running containers with default mounts and namespaces to facilitate debugging the host system.
These containers can then be used to install tools that you may need for troubleshooting.
Using Toolbx
You can create a new toolbox by running the command below. On the first run it will ask you if you want to download an image. Answer yes with y.
toolbox create my_toolboxYou can then list all the running toolboxes running on the host.
This should show you your newly created toolbox. In this case, it is named my_toolbox.
toolbox listAs pointed out by the output of the toolbox create my_toolbox command, you can enter the following command to enter your toolbox.
toolbox enter my_toolboxNow that you’re in the container, you can use the included dnf package manager to install packages.
For example, let’s install strace to look at read syscall done by the host’s toolbox utility.
sudo dnf install strace
# Some hosts directories are mounted at /run/host
strace -eread /run/host/usr/bin/toolbox listOnce done with your container, you can exit the container and then remove it from the host with the following command.
toolbox rm --force my_toolbox| Toolbx allows you to create toolboxes with your custom images. You can find more details in the toolbox manpages. |
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