Warnings & Limitations

This documentation is for Dash Enterprise.
Dash Enterprise is the fastest way to write & deploy Dash apps and
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Usage Limitations

• Only the owner of the app has the ability to create and rebuild a workspace, as well as use the IDE. Administrators—in addition to the app owner—can stop, restart, and delete the workspace. For more information, refer to Roles and Permissions.
• We are aware of an “Authentication failed” error when trying to git clone an app that you co-own over HTTPS in a workspace. To work around this
  issue, you can delete the contents of the ~/.gitconfig file, then run git clone again and supply your Dash Enterprise credentials when prompted.
• You can’t share the development site URL with anyone except administrators. This is
  by design: the development app frequently runs with
  app.run(debug=True) which is an insecure view for third
  parties. To share your app with others, deploy it.
• If your app includes a project.toml that uses environment variables to customize your app build (for example, the Python version used), these environment variables are not applied in workspaces.
• When developing your app with Workspaces, the minimum supported Dash version is dash==1.10 and the recommended version is dash==2.3.0 or later. If you are using a version of Dash prior to 2.3 and use the preview panel on an app running in a workspace, if you stop the app in the terminal, Dash’s front-end’s alert system prevents you from returning to the workspace.
• Python packages that are installed from C or C++ source code that require gcc cannot be installed within workspaces (but can be installed during app deployment). Most package versions newer than 2020 include prebuilt package wheels that don’t need compilation.
  For the numpy and statsmodels packages, numpy==1.17.3 and statsmodels==0.10.2 or later will successfully install in workspaces.
• Custom VS Code plugins and Jupyter plugins are not supported.
• When previewing apps that use Snapshot Engine in the Preview panel, PDF downloads are blocked by Chrome. Open a new tab and go to the development site to preview PDF downloads in Chrome.
• When previewing apps in the Preview panel, the fullscreen
  capabilities of Dash Design Kit only work in Chrome.
• Only app owners and administrators can view workspace logs in the App Info. If you are an administrator with access to the Kubernetes cluster that Dash Enterprise is installed on, you can also view workspace logs by connecting to the cluster. Then, use Lens or the kubectl commands below.

To view a workspace’s build logs (correspond to what is available in the App Info), make sure your kubectl context is set to the right cluster, and then run the following commands:

1. sh kubectl get pods -l app=workspace-<app-name> -n dash-apps | awk '{print $1}' | tail +2
   where <app-name> is the name of the app whose workspace build logs you want to view. The output is the name of the pod the workspace is running on.

2. sh kubectl logs <pod-name> dash-app-build -n dash-apps
   where <pod-name> is the name of the pod the workspace is running on.

To view a workspace’s debug logs (not available in the App Info), make sure your kubectl context is set to the right cluster, and then run the following command:

• sh kubectl logs -l app=workspace-<app-name> -n dash-apps
  where <app-name> is the name of the app whose workspace debug logs you want to view.

General Warnings

• Packages installed with pip in a workspace terminal are not persisted with rebuilds.
• There are no CPU limits within a workspace. Performing CPU intensive tasks within a workspace could cause resource issues for other apps.
• If using gunicorn or dash < 1.13.0 inside a workspace, then
  note that gunicorn or flask will print out a message like Listening at: <a href="http://0.0.0.0:8050.”>http://0.0.0.0:8050.</a> The app is not available at this URL. Instead, the app is available athttps://<your-dash-enterprise-server>/workspace/view/workspace-<appname>`
• Apps need to run on port 8050 (the default) within the workspace
  in order to preview them.
• Databases are shared between the deployed app and the
  workspace, which means that it is possible to delete data from a
  production database while using a workspace.
• Workspaces consume memory on the server even when they aren’t open.
• Closing a workspace does not stop a running development app. The development app continues to run and consume
  memory in the background. If your server is memory constrained, we
  recommend stopping the development app before closing your workspace, or even deleting old workspaces. Remember, you can quickly recreate them as needed.
• If running your development app causes your workspace to exceed its memory limit, the developement app is stopped and a killed message is printed in the terminal.
• The URL address bar of the preview tab does not update when
  navigating across multi-page apps. However, page
  navigation does work.

Debugging

• If your workspace has a process currently running in the
  terminal and you refresh the page, the workspace sometimes gets
  caught in a loading state. The solution to this is to empty your
  cache/cookies.

App Won’t Run with python app.py

If you run your app with python app.py and close your
browser, the process may continue running in the background. When
you reopen your workspace and run python app.py, you may find
that this fails as the previous app is still running. You may not
be able to terminate the previous process with ctrl+C as the previous
terminal view may not be available. To terminate the previously running
Python process, either:

• Save your files, add your recently installed packages to requirements.txt, and restart your workspace.

• List the Python processes with $ ps aux | grep python. Then, run $ pkill <pid> on the process IDs. For example,
  you might see:
  shell $ ps aux | grep python root 5446 1.9 0.2 236604 30868 pts/0 Sl+ 22:53 0:34 python app.py root 5557 2.8 2.7 4223340 429068 ? SLl 22:54 0:51 /usr/lib/theia/plugins/vscode-python/extension/languageServer.0.5.45/Microsoft.Python.LanguageServer root 6564 4.5 0.5 1138496 90080 pts/0 Sl+ 22:59 1:06 /app/.heroku/python/bin/python /workspace/app.py root 11721 0.0 0.0 11464 1088 pts/1 S+ 23:23 0:00 grep --color=auto python

in this case, you would run:
shell root@c4b0ace22eb0:/workspace# pkill 5446 root@c4b0ace22eb0:/workspace# pkill 6564