VSCode server on MetaCentrum machines

When developing with VSCode in MetaCentrum, a straightforward setup like:

project dir in $HOME dir
VSCode server running on frontend
connection to frontend through VSCode remote development

can be far too resource-expensive.

Frontends are not computing nodes

Resource-expensive (CPU, mem) processes running on frontends may be killed without warning.

Therefore, we recommend another setup with the VSCode server running on a computing node within a standard job.

VSCode running on a computing node

on your local station, generate a SSH key pair

ssh-keygen -f /home/username123/.ssh/my_key

choose a port number between 7000 and 30000 (e.g. 26759) and add the following sections to .ssh/config on your local station

# frontend section
Host tarkil.metacentrum.cz # your favourite frontend, e.g. tarkil
Port 22                    # keep standard port for ssh
PubkeyAuthentication no

# all other computing nodes
Host *.cerit-sc.cz *.fav.zcu.cz *.fzu.cz *.grid.cesnet.cz *.hw.elixir-czech.cz *.ibot.cas.cz *.ics.muni.cz *.metacentrum.cz *.meta.zcu.cz *.natur.cuni.cz *.nti.tul.cz *.ueb.cas.cz
Port 26759                       # chosen port number
IdentityFile path_to_private_key # Path to private key from step 1

within a job, setup direct connection to computing node for VSCode remote development


# make another (server-side) SSH key pair and store it in a scratch dir
mkdir -p "$SCRATCHDIR/.ssh"
chmod 700 "$SCRATCHDIR/.ssh"

rm -f "$SCRATCHDIR/.ssh/server_key" "$SCRATCHDIR/.ssh/server_key.pub"
ssh-keygen -f "$SCRATCHDIR/.ssh/server_key" -N "" -C "VSCode" -q -t ed25519
echo "SSH key generated"

# to $SCRATCHDIR/.ssh/authorized_keys, add public key from step 1
touch "$SCRATCHDIR/.ssh/authorized_keys"
chmod 600 "$SCRATCHDIR/.ssh/authorized_keys"

PUBKEY='ssh-ed25519 AAAAXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX3wN3+QgMAVJERjayo user123@PC'
grep -q "$PUBKEY" "$SCRATCHDIR/.ssh/authorized_keys" || echo "$PUBKEY" >> "$SCRATCHDIR/.ssh/authorized_keys"

echo "Public key added to authorized_keys"

# make sure that the chosen port is free
PORT=26759
netstat -tan |grep -q "0.0.0.0:$PORT " && { echo "port $PORT is busy" >&2; exit 1; }

# on the computational node, start running ssh server demon that listens on $PORT port
echo "Starting SSH server"
/usr/sbin/sshd -D -p $PORT -o "HostKey $SCRATCHDIR/.ssh/server_key" -o "PermitRootLogin no" -o "PasswordAuthentication no" -o "ChallengeResponseAuthentication no" &

echo "SSH running on $(hostname):$PORT"
echo "Connect to:" hostname

Through VSCode remote development, connect to hostname and PORT.

VSCode server on MetaCentrum machines

VSCode running on a computing node

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