SSH config to allow VS Code Remote SSH to connect to a fresh new SLURM job running on a remote HPC system

SLURM_vs_code_ssh_config.txt

# ssh config to use with VS Code Remote SSH
# to launch a VS Code remote ssh session inside of 
# a new SLURM compute job running on the remote HPC

# when you start a new ssh session from your LOCAL laptop,
# SLURM will spin up a new srun job and connect to the ssh daemon on the compute node
# your ssh connection will thus tunnel from your LOCAL laptop
# through the head node, to the compute node
# the SLURM job on the compute node will remain active until it expires via time limit
# the SLURM job will terminate when the ssh session is closed
# when you connect VS Code in this way via the Remote SSH extension,
# the VS Code remote server processes will run INSIDE THE COMPUTE NODE 
# do you dont BLOW UP THE HEAD NODE with any VS Code tasks
# the default behavior of VS Code with Remote SSH is to attempt to re-connect if the ssh connection is lost
# so every time the SLURM job expires, VS Code will just automatically re-connect, triggering a new SLURM job
# and your VS Code session should continue largely uninterrupted

# REQUIREMENTS
# - able to ssh into the HPC head node
# - able to ssh into a running HPC compute node, from the head node
# - desktop VS Code app installed
# - VS Code Remote SSH extension installed

# start an interactive ssh session like this;
# $ ssh slurm-compute-node
#
# launch VS Code directly with this;
# $ code --remote ssh-remote+slurm-compute-node /home/my-username


Host slurm-compute-node
    User   my-username
    #
    # make sure the .pub key for this key is added to ~/.ssh/authorized_keys on the HPC
    IdentityFile ~/.ssh/keys/id_ed25519
    #
    # put your alias to the HPC Cluster head node here after 'ssh';
    ProxyCommand ssh my-slurm-hpc "bash -l -i -c 'srun --job-name=vs-code-session --nodes=1 --ntasks=1 --time=04:00:00 --pty bash -l -i -c \"exec nc localhost %p\" ' "
    #
    # wait up to 10 minutes for connection ; it can take a while for a new SLURM node to spin up
    ConnectTimeout 600
    #
    # once connected, keep the tunnel alive
    ServerAliveInterval 60
    ServerAliveCountMax 10


Host my-slurm-hpc
    #
    # put your ssh config to log into the remote HPC head node here
    #
    ProxyCommand lots-of-complicated-stuff-goes-here
    #
    IdentityFile ~/.ssh/keys/id_ed25519
    User   my-username
    ServerAliveInterval 60
    ServerAliveCountMax 10
    
    



# NOTE: supposedly some of these might also work
#  ProxyCommand ssh my-slurm-hpc \
#    "bash -l -i -c '\
#       srun --job-name=vs-code-ssh --nodes=1 --ntasks=1 --time=04:00:00 --pty ssh -o BatchMode=yes -o StrictHostKeyChecking=yes -W localhost:%p $(whoami)@localhost '"

# srun --nodes=1 --ntasks=1 --pty ssh -W localhost:%p $(whoami)@localhost