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Code Server is an open-source tool similar to VS Code, and it brings the functionality of VS Code to your browser. Important -As an open-source tool, code-server is not displaying or allowing the installation of some extensions (e.g., Copilot, Copilot Chat, other GitHub-related extensions), due to proprietary restrictions.

This page shows you how to install and run VS Code using your local browser. Let us know if you have any questions.

Connect to O2

Please review the How to Login to O2 and the Using Slurm Basic wiki pages for more details. If using a Windows computer, we recommend to download/install https://mobaxterm.mobatek.net/and open a new terminal. If using a Mac computer, you can open the ‘Terminal’ app and use the ssh command as follow:

# Select a port between 50000 to 60000 for yourself using the command 'netstat' in a local terminal. Select a port that says 'listening' or 'established'.
export PORT=51234 
export CLUSTER_USER=YourHMSID 
ssh -L $PORT:127.0.0.1:$PORT $CLUSTER_USER@o2.hms.harvard.edu

Run the latest version (

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4.20.0)

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using a container

# Export the port number
export PORT=51234 

# Launch an interactive job (resources: 2 hours and 3 GiB of RAM) 
srun --pty -p priority -t 0-2 --mem=3G --tunnel $PORT:$PORT bash

# Start code-server using the singularity container
singularity exec /n/app/singularity/containers/code-server-v4.20.0.sif /app/code-server/bin/code-server

# In theory, you should see something similar to:
singularity exec /n/app/singularity/containers/code-server-v4.20.0.sif /app/code-server/bin/code-server
[2024-01-11T17:15:54.233Z] info  code-server 4.20.0 
[2024-01-11T17:15:54.237Z] info  Using user-data-dir /home/<HMS_ID>/.local/share/code-server
[2024-01-11T17:15:54.264Z] info  Using config file /home/<HMS_ID/.config/code-server/config.yaml
[2024-01-11T17:15:54.265Z] info  HTTP server listening on http://127.0.0.1:50003/
[2024-01-11T17:15:54.265Z] info    - Authentication is enabled
[2024-01-11T17:15:54.266Z] info      - Using password from /home/<HMS_ID>/.config/code-server/config.yaml
[2024-01-11T17:15:54.266Z] info    - Not serving HTTPS
[2024-01-11T17:15:54.267Z] info  Session server listening on /home/<HMS_ID/.local/share/code-server/code-server-ipc.sock

# To see the password on /home/<HMS_ID>/.config/code-server/config.yaml
# You'll need to open a new terminal, connect to O2, and paste the following command:
cat ~/.config/code-server/config.yaml

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Installing and

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Testing an Older Version Locally

export PORT=51234 
srun --pty -p priority -t 8:0:0 --tunnel $PORT:$PORT bash 

mkdir -p ~/.local/lib ~/.local/bin
curl -fL https://github.com/cdr/code-server/releases/download/v4.7.0/code-server-4.7.0-linux-amd64.tar.gz | tar -C ~/.local/lib -xz
mv ~/.local/lib/code-server-4.7.0-linux-amd64 ~/.local/lib/code-server-4.7.0

# Start code server
~/.local/lib/code-server-4.7.0/bin/code-server 

# You should see output: 
$ [2021-10-05T13:58:56.961Z] info  code-server 4.7.0 4cd55f94c0a72f05c18cea070e10b969996614d2
[2021-10-05T13:58:56.962Z] info  Using user-data-dir ~/.local/share/code-server
[2021-10-05T13:58:56.995Z] info  Using config file ~/.config/code-server/config.yaml
[2021-10-05T13:58:56.995Z] info  HTTP server listening on http://127.0.0.1:51234
[2021-10-05T13:58:56.995Z] info    - Authentication is enabled
[2021-10-05T13:58:56.995Z] info      - Using password from ~/.config/code-server/config.yaml
[2021-10-05T13:58:56.995Z] info    - Not serving HTTPS

# Command + click the "http://127.0.0.1:51234" to open the link
# Then copy and paste the password to browser
cat ~/.config/code-server/config.yaml

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Create an Alias to login,

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start an interactive job

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, and launch code-server from a local machine

# Set DUO default to push if you didn’t do it yet. 
# Run this command on O2:  
echo export DUO_PASSCODE=push >> $HOME/.bashrc

# On your local machine
# set up alias. You could add this row one of the following two lines to your ~/.bash_profile

# If using an older version:
alias vscode_old='PORT=51234; CLUSTER_USER=YourHMSID; ssh -L $PORT:127.0.0.1:$PORT $CLUSTER_USER@o2.hms.harvard.edu -t "hostname; echo port is: $PORT; kill -9 $(/usr/sbin/lsof -t -i:$PORT) 2>/dev/null; srun --pty -p priority -t 8:0:0 --tunnel $PORT:$PORT bash -c \"hostname; echo port is: $PORT; kill -9 $(/usr/sbin/lsof -t -i:$PORT) 2>/dev/null; export PORT=$PORT; ~/.local/lib/code-server-4.7.0/bin/code-server & bash;\""'

# loginIf using tothe O2,latest start interative job and run vs code server
vscode

“port 51234 is in use or unavailable"? Make sure you close the VS Code editor page within your browser

# If you see this error: 
channel 3: open failed: connect failed: Connection refused
channel 3: open failed: connect failed: Connection refused
login03.o2.rc.hms.harvard.edu
port is: 51234
port 51234 is in use or unavailable
Connection to o2.hms.harvard.edu closed.

Make sure you close the VS Code editor page with your browser

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version (4.20.0)
alias vscode='PORT=50234; CLUSTER_USER=YourHMSID; ssh -L $PORT:127.0.0.1:$PORT $CLUSTER_USER@o2.hms.harvard.edu -t "hostname; echo port is: $PORT; kill -9 $(/usr/sbin/lsof -t -i:$PORT) 2>/dev/null; srun --pty -p priority -t 8:0:0 --tunnel $PORT:$PORT bash -c \"hostname; echo port is: $PORT; kill -9 $(/usr/sbin/lsof -t -i:$PORT) 2>/dev/null; export PORT=$PORT; singularity exec -B '/n' /n/app/singularity/containers/code-server-v4.20.0.sif /app/code-server/bin/code-server & bash;\""'

# login to O2, start interative job and run vs code server
vscode

Frequently Asked Questions (FAQ)

Why I see “port 51234 is in use or unavailable" when launching code-server?

Please select a different port number in the 50,000 range.

Why am I encountering the message “channel #: open failed: connect failed: Connection refused" in the terminal?

You have a code-server tab open in your browser. The solution is to simply close the tab or tabs.