FAQs & Troubleshooting¶

User troubleshooting guide¶

Session list is not displayed correctly¶

Due to intermittent network problems and/or other various reasons, session list may not be displayed correctly. Most of the time, this problem will disappear just by refreshing the browser.

Web-based Web-UI: Refresh the browser page (use the shortcut provided by browsers such as Ctrl-R). Since the browser’s cache may cause troubles sometimes, it is recommended to refresh the page bypassing the cache (such as Shift-Ctrl-R, but the keys may differ in each browser).
Web-UI App: Press Ctrl-R shortcut to refresh the app.

How to install apt packages?¶

Inside a compute session, users cannot access root account and perform operations that require sudo privilege for security reasons. Therefore, it is not allowed to install packages with apt or yum since they require sudo. If it is really required, you can request to admins to allow sudo permission.

Alternatively, users may install packages by brew. To install and use brew from the compute session, follow the commands below:

$ /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
$ test -d ~/.linuxbrew && eval $(~/.linuxbrew/bin/brew shellenv)
$ test -d /home/linuxbrew/.linuxbrew && eval $(/home/linuxbrew/.linuxbrew/bin/brew shellenv)
$ test -r ~/.bash_profile && echo "eval \$($(brew --prefix)/bin/brew shellenv)" >>~/.bash_profile
$ echo "eval \$($(brew --prefix)/bin/brew shellenv)" >>~/.profile

Now, you can install packages by brew:

$ brew install hello

brew installs packages under ~/.linuxbrew. So, if you create a storage folder named .linuxbrew, which will be automatically mounted when creating a compute session, those installed packages can be kept after compute session is destroyed and then reused for the next compute session.

How to install packages with pip?¶

By default, when you install a pip package, it will be installed under ~/.local. So, if you create a automount data folder named .local, you can keep the installed packages after a compute session is destroyed, and then reus them for the next compute session. Just install the packages with pip like:

$ pip install aiohttp

I have created a compute session, but cannot launch Jupyter Notebook¶

If you installed a jupyter package with pip by yourself, it may be conflict with the jupyter package that a compute session provides by default. Especially, if you have created ~/.local directory, the manually installed jupyter packages persists for every compute session. In this case, try to remove the .local automount folder and then try to launch Jupyter Notebook again.

Page layout is broken¶

Backend.AI Web-UI utilizes the latest modern JavaScript and/or browser features. Please use the LATEST versions of moder browsers (such as Chrome).

SFTP disconnection¶

When Web-UI App launches SFTP connection, it uses a local proxy server which is embeded in the App. If you exit the Web-UI App during the file transfer with SFTP protocol, the transfer will immediately fail because the connection established through the local proxy server is disconnected. Therefore, even if you are not using a compute session, you should not quit the Web-UI App while using SFTP. If you need to refresh the page, we recommend using the Ctrl-R shortcut.

If the Web-UI App is closed and restarted, the SFTP service is not automatically initiated for the existing compute session. You must explicitly start the SSH/SFTP service in the desired container to establish the SFTP connection.

Admin troubleshooting guide¶

Users cannot launch apps like Jupyter Notebook¶

There may be a problem on connecting WSProxy service. Try to stop and restart the service by referencing the guide on start/stop/restart WSProxy service.

Indicated resources do not match with actual allocation¶

Occasionally, due to unstable network connections or container management problem of Docker daemon, there may be a case where the resource occupied by Backend.AI does not match with the resource actually used by the container. In this case, follow the steps below.

Login as admin account.
Visit Maintenance page.
Click the RECALCULATE USAGE button to manually correct the resource occupancy.

Image is not displayed after it is pushed to a docker registry¶

Note

This feature is only available for superadmins.

If a new image is pushed to one of the Backend.AI docker registries, the image metadata must be updated in Backend.AI to be used in creating a compute session. Metadata update can be performed by clicking the RESCAN IMAGES button on the Maintenance page. This will update metadata for every docker registry, if there are multiple registries.

If you want to update the metadata for a specific docker registry, you can go to the Registries tab in Environments page. Just click the refresh button in the Controls panel of the desired registry. Be careful not to delete the registry by clicking the trash icon.