Open OnDemand

Open OnDemand is a open source project by the Ohio Supercomputer Center that provides a web portal for HPC users. It is designed as a platform allowing system administrators to add additional modules or 'apps'. Users can use this platform to launch interactive jobs or VNC/SSH sessions, view their job statuses, interact with their files. It supports a variety of authentication mechanisms including federated authentication (OpenID, CAS, Shiboleth) or with an the system's underlying PAM (ldap, password file, etc.).

Open OnDemand is in use by:

• https://arc-ts.umich.edu/greatlakes/user-guide/#document-3
• Yale: https://docs.ycrc.yale.edu/clusters-at-yale/access/ood/

Interactive Apps

App Development

On Open OnDemand 1.8, you can only enable a specific user access to development mode by creating a directory /var/www/ood/apps/dev/$username, then symlinking /var/www/ood/apps/dev/$username/gateway to /home/$username/openondemand/dev. Restart the PUN web server. A 'Develop' section should appear in the navbar. This will only work for $username.

See: https://osc.github.io/ood-documentation/latest/app-development/enabling-development-mode.html#enable-in-ondemand-v1-6

It may help to look at other apps that are available at: https://osc.github.io/ood-documentation/latest/install-ihpc-apps.html

Deploying an app

Once you have done developing an app, deploy it by moving it to /var/www/ood/apps/sys.

Jupyter Notebooks

Running a Jupyter Notebook interactive app requires tweaking the example OSC Jupyter Interactive App (https://github.com/OSC/bc_example_jupyter) to work in your environment. Before you get started, you should be able to submit jobs via Open OnDemand. If this isn't working, fix your configuration before proceeding with interactive apps.

The easiest way to get this working is to enable App Development on an account and then testing from this account.

1. Enable App Development on your account
2. Clone the OSC Jupyter app to ~/ondemand/dev/bc_example_jupyter
3. Tweak the form.yml (or form.yml.erb). Add or remove fields as required by you.
4. Tweak submit.yml.erb to work in your environment.
5. Try launching a Jupyter notebook and fix any issues as you go.

Remote Desktop

Out of the box, trying to make a desktop results in:

The cluster was never set. Either set it in form.yml.erb with `cluster` or `form.cluster` or set `cluster` in submit.yml.erb.

• The Desktop session data for this session can be accessed under the staged root directory.

You need to tweak the form to work in your environment. You need to edit either define the cluster value in /var/www/ood/apps/sys/bc_desktop/form.yml or launch your own interactive app. Like the Jupyter notebooks, you may want to offer the user a list of partitions that they can run their VNC session on. Do so by editing form.yml or converting it to a .erb so that you can run system commands to obtain all the slurm partitions to list.

VNC: Failed to connect to server

Launching the VNC session opens noVNC. However, I got "Failed to connect to server". Error from apache logs show:

==> httpd/error.log <==                                                                                                                                                       
[Fri Jan 22 03:12:49.324498 2021] [proxy:error] [pid 5386:tid 140231151974144] (111)Connection refused: AH00957: WS: attempt to connect to 172.28.0.5:32316 (*) failed        
[Fri Jan 22 03:12:49.324540 2021] [proxy_wstunnel:error] [pid 5386:tid 140231151974144] [client 136.159.79.128:54416] AH02452: failed to make connection to backend: c2

which is weird because c2 is actually listening on port 5901 not 32316. The job output however clearly shows the websockify binary not being found. Fixing this fixed the VNC connection issue.

Solution: Ensure websockify is found. If it's installed in a nonstandard location, tweak your clusters.d yaml file so that the batch_connect/vnc has a script_wrapper that exports the websockify path as WEBSOCKIFY_CMD.

batch_connect:
    basic:
      script_wrapper: |
        %s
      set_host: "host=$(hostname -A | awk '{print $1}')"
    vnc:
      # websockify by pip3 is in /usr/local/bin
      script_wrapper: |
        module purge
        export PATH="/opt/TurboVNC/bin:$PATH"
        export WEBSOCKIFY_CMD="/usr/local/bin/websockify"
        %s
      set_host: "host=$(hostname -A | awk '{print $1}')"

No Home Environment Error

Setting VNC password...
Error: no HOME environment variable
Starting VNC server...
vncserver: The HOME environment variable is not set.
vncserver: The HOME environment variable is not set.
vncserver: The HOME environment variable is not set.
vncserver: The HOME environment variable is not set.
vncserver: The HOME environment variable is not set.

Slurm job output showed this. It turns out, the nodes I've set up didn't have the user account so it didn't know what the user's home directory is.

Solution: Ensure your system has the user account.

Job Composer

To install it, see:

• https://osc.github.io/ood-documentation/latest/applications/job-composer.html
• https://osc.github.io/ood-documentation/latest/customization.html#custom-job-composer-templates

The actual Job Composer app is at https://github.com/OSC/ondemand/tree/master/apps/myjobs

CSRF Fail, resulting in 'The change you wanted was rejected'

For some reason, when trying to create a new job or new template, I get "The change you wanted was rejected.". PUN logs show FATAL "ActionController::InvalidAuthenticityToken (ActionController::InvalidAuthenticityToken):".

This was only 'fixed' by disabling CSRF by injecting Rails.application.config.action_controller.forgery_protection_origin_check = false into config/initializers/new_framework_defaults_5_2.rb. This is most likely caused by either Traefik (likely) or nginx doing the reverse proxy somehow causing the CSRF check to fail due to a difference in base_url. In fact, this issue prevails across all the other interactive apps and may require the same fix as well.

See also, this issue: https://github.com/rails/rails/issues/22965.

Shell / Terminal Access

The Shell App basically just runs a web SSH client from the Open OnDemand server. You limit which hosts it can connectt to by tweaking the env file:

DEFAULT_SSHHOST="arc.ucalgary.ca"
OOD_SSHHOST_ALLOWLIST="arc.ucalgary.ca"

Failed to establish a websocket connection.

After setting up OnDemand, I had a hard time getting the SSH app to connect. I kept on getting:

Failed to establish a websocket connection. Be sure you are using a browser that supports websocket connections.

Debugging the socket revealed that it was getting a 401 error from PUN. At first, I thought the reverse proxy (traefik 1.7) wasn't forwarding the authentication headers, but this was a red herring. Something with the PUN application was throwing this 401 error. I verified that the node is able to SSH and that the default hostname is correct in /etc/ood/config/apps/shell/env. I even tried connecting to a specific host to no avail. I then set OOD_SSH_WRAPPER=/test.sh with test.sh just dumping the environment to a tmp file which showed me that it wasn't even reaching the point of calling the SSH wrapper. OOD 1.8 also requires setting the OOD_SSHHOST_ALLOWLIST, but that didn't help.

Solution: This only worked after setting OOD_SHELL_ORIGIN_CHECK='off'

Troubleshooting

Logs are stored at:

• /var/log/ondemand-nginx/
• /var/log/httpd/

Apps are stored at:

• /var/www/ood/apps/sys
• /var/www/ood/apps/dev/$username/gateway (symlinked to user's home directory ~/ondemand/dev)