Mapping Local Directories

This documentation is for Dash Enterprise.
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Local directory mapping is available for Dash Enterprise Single Server versions 2.5.0 to 4.3.0. This page applies to Dash Enterprise 4.

In Dash Enterprise, Dash apps are run in isolated containers. Dash Enterprise builds the entire system for each individual app from scratch, including installing a fresh instance of Python, installing dependencies, and more. This isolation and containerization is great: it allows for one app’s dependencies to not impact the next app’s and, from a security perspective, ensures that apps can’t modify or access the underlying server. One part of this isolation is that each app has its own “ephemeral” filesystem. This means that:

• By default, files that are saved in the app’s environment aren’t
  persisted across deploys.
• By default, files (even networked file systems) that are on the actual
  physical server aren’t actually accessible to the app.

Mapping filesystems from the underlying server into the app allows you to save files
persistently as well as read files from the underlying server, including networked file systems.

Because this feature has security implications, only directories specified in the Dash Enterprise Server Manager can be mapped to Dash apps.

Approving Directories for Mapping

A server administrator with access to https://<your.plotly.domain>:8800/settings can allow certain directories on the host server to be mapped to Dash apps. Go to the Allowed Directories for Mapping section of the settings page and enter the path(s) of approved directories.

Adding Directory Mapping

To add a directory mapping via the Dash Enterprise UI,
navigate to the app Settings and scroll down to
Directory Mappings. Here, use the text boxes to
add the Host Path and App Path. For example, /srv/app-data
and /data.

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If the directory you’re trying to map from isn’t admin-approved, you will see an error
message.

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Referencing the File System in Your Code

If you have mapped the directory from /srv/app-data to /data, then you
can read files from this folder in your app with the following code:

import os
file_pathname = os.path.join(os.sep, 'data', 'my-dataset.csv')

In some cases, the filesystems that you reference in your deployed
app may be different from those that you reference locally.
In your app code, you can check which environment you are in
with the following code:

if 'DASH_APP_NAME' in os.environ:
    # this is a deployed app
    filepath = os.path.join(os.sep, 'data', 'my-dataset.csv')
else:
    # local file path
    filepath = os.path.join(os.sep, 'Users', 'chris', 'data', 'my-dataset.csv')

Recommendations

If you are mounting a filesystem, we have the following recommendations:

• Try to isolate the data that you need into its own app-specific folder.
• Do not mount the entire filesystem.
• Do not mount system directories, like those under /usr.
• As per the
  “Filesystem Hierarchy Standard (FHS)”,
  folders inside the /srv folder would be a good, conventional place
  to host app-level data.
• This feature also works with networked filesystems. Note that this
  requires some extra configuration in the underlying server by your
  server administrator. In particular, the network filesystem should be
  added to the /etc/fstab file on the underlying server. For more
  information, see this
  RHEL7 and CentOS documentation on CIFS and NFS,
  the official Ubuntu NFS documentation,
  or the official Ubuntu CIFS documentation.

Removing Directory Mapping

To remove directory mappings via the Dash Enterprise UI, select Delete.

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