SSH connection setup¶

slurmhub uses paramiko (a pure-Python SSH library) to talk to the cluster. Everything you can do with the regular ssh command — key auth, password auth, jump hosts, agent forwarding, host aliases — works here too.

Tip

The recommended setup is passwordless key authentication via an SSH config alias. It lets the app reuse a single SSH connection across all the Slurm commands it issues and removes the need to type a password every time the auto-refresh runs.

Generate an SSH key¶

ssh-keygen -t ed25519 -C "your_email@example.com"

Press Enter at each prompt to accept the defaults. You can optionally set a passphrase; if you do, run ssh-add so the key is unlocked once per login session.

Copy your public key to the cluster¶

ssh-copy-id your-username@login.cluster.example.org

You will be prompted for your cluster password one last time. After this, key-based login should work:

ssh your-username@login.cluster.example.org 'squeue --me'

Add a host alias (strongly recommended)¶

Open or create ~/.ssh/config and add:

Host mycluster
    HostName       login.cluster.example.org
    User           your-username
    IdentityFile   ~/.ssh/id_ed25519
    Port           22

    # ControlMaster greatly reduces the per-command SSH overhead.
    # It opens one underlying TCP connection per host and reuses it.
    ControlMaster  auto
    ControlPath    ~/.ssh/control-%r@%h:%p
    ControlPersist 10m

slurmhub automatically reads ~/.ssh/config and resolves hostnames, usernames, ports, identity files, and ProxyCommand entries. Once the alias works:

ssh mycluster 'echo ok'

you can reference it in config.toml as simply:

[profiles.cluster]
host = "mycluster"

Connecting through a bastion / jump host¶

The cleanest approach is SSH’s native ProxyJump:

Host bastion
    HostName  bastion.example.org
    User      your-username

Host mycluster
    HostName  login.cluster.example.org
    User      your-username
    ProxyJump bastion

Alternatively, declare the jump host directly in your slurmhub config:

[profiles.cluster]
host = "login.cluster.example.org"
ssh.username  = "your-username"
ssh.jump_host = "bastion.example.org"

Password authentication¶

If you cannot use keys, leave the password fields empty in the config — the app will detect the auth failure on the first refresh and pop up an interactive password prompt.

Important

The password is held in memory only — it is never written to disk. You get up to three attempts before the app stops re-prompting; restart slurmhub to retry after that.

Verifying the cluster side¶

Before launching the TUI, confirm that the basic Slurm commands respond:

ssh mycluster 'squeue --me'           # should list (or empty) your jobs
ssh mycluster 'sinfo -h -o "%R|%D"'   # should list partitions
ssh mycluster 'sacct -X -n | head -5' # should list recent history

If any of these hang or fail, fix the SSH or Slurm side first; the TUI will surface the same errors but the diagnostics are easier to read from the shell.