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Remote Debugging with VSCode

We have recently made it possible to connect to Alma from VSCode - though only to the login nodes.

Instructions are fairly brief covering all the components involved - any more information needed about any component contact the helpdesk.

The full details are given by microsoft here: remote-ssh with vscode

An adaptation for Alma follows:

Installation

SSH host setup

  • You need an ssh key/pair for Alma set up. You can find the instructions in the 'First Steps' tab under 'Setting up ssh key for Alma'.

EITHER:

Connect to a remote host: login node

  • In VSCode you need to check that you can ssh onto alma in a VSCode terminal.
  • In VSCode select "Connect to host" after clicking on the "remote window" icon in the far left bottom of the toolbar
  • enter ssh username@alma.icr.ac.uk
  • Select the directory with your ssh key

This will now create the connection. In the future you will be able to select this from the list when you choose a remote connection.

Alma has a 200MB memory limit for the login nodes, so you will need to use the interactive nodes for any real work. Do not use login node to run code, use compute node. Once connected to your code with the remote-ssh extension you can use edit your code with the login node but can have the terminal in VSCode as part of an interactive session for running it.

Interactive session in VSCode terminal

  • Select alma.icr.ac.uk from the list when you choose a remote connection and connect to the login node
  • Now that you are connected to the login node, open the VSCode terminal and select the needed number of resource. An example is the following srun command: 
    srun --pty --mem=10GB -c 2 -t 30:00:00 -p interactive bash

This will now create the connection to a compute node 01, since we asked for many resources. From here, you can run and test your code.

OR:

Connect to a remote host: compute node

  • You will need to first log in to an interactive node on Alma with a terminal using: 
    ssh username@alma.icr.ac.uk
srun --pty --mem=10GB -c 2 -t 30:00:00 -p interactive bash
  • in VSCode select "Connect to host" after clicking on the "remote window" icon in the far left bottom of the toolbar
  • enter ssh -J username@alma.icr.ac.uk node01
  • Select the directory with your ssh key

This will now create the connection. In the future you will be able to select this from the list when you choose a remote connection, but you will still need to first access a log in node from a terminal.

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