UW HYAK Code-Server Instructions

Solution to connect VS Code (code-server) to HYAK klone via a docker container using apptainer.

This solution:

1. Provides a method to connect VS Code to a compute node on klone, preserving the login nodes for the community. While developing your code with connectivity to the server is a great usage of our services, connecting directly to the login node via the Remote-SSH extension will result in VS Code server processes running silently in the background and leading to node instability. As a reminder, we prohibit users running processes on the login node.

2. Uses a server to develop and execute your code reducing battery usage. code-server handles the VSCode background processes, preventing them from slowing down your local machine.

3. Provides an alternative to a ProxyJump, which for Windows users requires 2-factor authentication to login and change directory.

Background Reading

Coder Home

Code-server github repo

Code-server documentation

DockerHub page

One of a few YouTube videos explaining the benefits of Code-server

Pull the Container

Note: This solution was developed for UW HYAK users to use SLURM in an HPC environment. The instructions do not necessarily serve every purpose.

Recommended: perform the following steps after starting an interactive job with salloc and load the apptainer module. It is best to do this in a workspace directory rather than the storage limited $HOME directory.

$ apptainer pull docker://codercom/code-server

This will pull and build the code-server container file called code-server_lastest.sif

Launch code-server with SLURM

Download the SLURM batch script.

$ wget https://github.com/finchnSNPs/hyak-code-server/blob/main/code-server.job

Edit the job script (find comments "#update this line") to set your code-server session home directory and provide the name of the container if it does not match code-server_latest.sif, and edit the SBATCH directives as needed.

$ sbatch code-server.job
Submitted batch job 17440706

This script will start a batch job and launch the code-server container. The SSH tunneling instructions, including the code-server session password, will be written to the output file (stdout). Concatenate the output file for tunneling instructions. The following is an example output.

$ cat code-server.job.17440706
1. SSH tunnel from your workstation using the following command:

   ssh -N -L 8080:n3088:59985 [email protected]

   and point your web browser to http://localhost:8080

2. log in to Code Server using the following credentials:

   password: +WwYzgh7YH/yHzUWNWNS

When done using Code Server, terminate the job by:

1. Sign out of Code Server (Find the three-lines icon Menu and select "Sign out of Code Server")
2. Issue the following command on the login node:

      scancel -f 17440706

You can monitor the job with squeue and your UWNetID like the following example.

$ squeue -u finchkn
             JOBID PARTITION     NAME     USER ST       TIME  NODES NODELIST(REASON)
          17440706   compute code-ser  finchkn  R       3:15      1 n3088

The output file will also contains messages from code-server as the connection is established. These messages include:

1. The storage location of session associated files - .local/share/code-server

2. The location of the configuration file for the session which contains the password that is also printed in the output file - .config/code-server/config.yaml

3. Which IP and Port code-server HTTP and session is listening to.

As your session continues, more information will be printed to this output file.

Establish the SSH tunnel

Follow the instructions in the output file. Open a new terminal/powershell/Putty window and use the command:

$ ssh -N -L 8080:n3088:59985 [email protected]
... provide UWNetID password
... Duo 2 Factor Authentication

The login will appear to hang, but your connection is now open.

Open a new browser window to http://localhost:8080

Provide the password from the output file in the browser. Select theme and get coding. Extensions can be installed through the browser and will be stored in .local/share/code-server/extensions.

If you have trouble with this method, please report them here or to UW Help with HYAK in the message.

Using Code-Server without the SLURM script

This section details how to start code-server manually should issues arise using the script or if you would like to change the code-server environment.

Perform the following steps after starting an interactive job with salloc and load the apptainer module.

Get the hostname for the compute node where the interactive job is active.

$ hostname

Find an open socket.

$ /mmfs1/sw/pyenv/versions/3.9.5/bin/python -c 'import socket; s=socket.socket(); s.bind(("", 0)); print(s.getsockname()[1]); s.close()'

These two pieces become the components of the --bind-addr passed to code-server.

Start code-server. The following is an example that should be changed to fit your purposes:

$ apptainer exec --cleanenv --home /gscratch/scrubbed/finchkn/ /gscratch/scrubbed/finchkn/code-server_latest.sif code-server --bind-addr=n3100:48473 --auth=password

Open a new terminal/powershell/Putty window and use the command:

$ ssh -N -L 8080:n3100:48473 [email protected]
... provide UWNetID password
... Duo 2 Factor Authentication

The login will appear to hang, but your connection is now open.

Open a new browser window to http://localhost:8080

The password is in the configuration file, which for this example is:

$ cat /gscratch/scrubbed/finchkn/.config/code-server/config.yaml
bind-addr: 127.0.0.1:8080
auth: password
password: 8RgcAlYVbiGYp/zODwcA
cert: false

Paste the password from the config file into the browser.

Sign out of Code Server (Find the three-lines icon Menu and select "Sign out of Code Server"), and stop the process on the compute node (with Control + C ; ^C) and exit the interactive job.

This configuration file can be edited to change locations for where session files are stored among other settings and preferences. A preferred password can also be provided by changing password: in this file.