It took a while to figure this out, so I might as well document this. Looking at the amount of search hits on this subject, I wasn’t not the only one that needed access to the host itself.
When debugging an issue related to the OS or docker, you might need access to the host itself. The Terminal & SSH Add-on drops you in a container, while this might be enough for users, you sometimes want to access the real operating system, to examine some docker issue for example.
There is a well written documentation on how to do this here: Debugging the Home Assistant Operating System | Home Assistant Developer Docs but this only works nicely when you are running HA on a Raspberry Pi. When running HA in a VM like on Proxmox, it’s more difficult to map an USB stick to be able to copy the file. Note that these steps below do the exact same thing as the copy does.
You’ll first need to login to the host itself, trough the host console. You can do this from within the interface of Proxmox. Just open the console, and login with root, you don’t need a password. Then, use login to drop to a shell. This is enough to access the host shell, but since the console doesn’t work nicely, we want to continue to enable SSH.
Now, I assume you are already running the Terminal & SSH Add-on, and have it configured with your public key. Go to your .ssh directory by running cd /root/.ssh/, and next, copy the authorized_keys file to the host. You can do this with docker cp addon_core_ssh:/root/.ssh/authorized_keys . (Note the single dot at the end of the command). To be sure, give it the right permissions, but this should already be the case. chmod 600 authorized_keys
Finally, you’ll need to start dropbear. You can do this with systemctl start dropbear.
You can now connect to your host with ssh root@hass -p 22222. Replace the hostname if needed.
I may have misunderstood the instructions or my problems are from running the VM in ESXi rather than Proxmox.
Where does one type the docker command to copy authorized_keys? If I do it at the HA prompt, I get the docker help command output. If I first use login to get into the host OS and then type the command, I get an error about trying to do this on a read-only file system.
After that, where do I type the chmod and service commands?
If your goal is just to be able to use the docker CLI thre’s a much simpler solution. Install the SSH & Web Terminal addon (the one from the community add-ons repo not the one in the offical addons repo) and then turn off protection mode. You’re still ssh’ing into a container but then the docker CLI is available to you.