Introduced in 0.5.0
The preferred method to mount external containers to a Dokku managed container, is to use the Dokku storage plugin.
storage:ensure-directory [--chown option] <directory> # Creates a persistent storage directory in the recommended storage path storage:list <app> [--format text|json] # List bind mounts for app's container(s) (host:container) storage:mount <app> <host-dir:container-dir> # Create a new bind mount storage:report [<app>] [<flag>] # Displays a checks report for one or more apps storage:unmount <app> <host-dir:container-dir> # Remove an existing bind mount
The storage plugin is compatible with storage mounts created with the docker-options. The storage plugin will only list mounts from the deploy/run phase.
The storage plugin supports the following mount points:
- explicit paths that exist on the host
- docker volumes
Listing persistent storage¶
Persistent storage bind mounts are specified on a per-app basis, and can be listed with the
The output format can also be set to
json for programmatic access:
Creating storage directories¶
Introduced in 0.25.5
A storage directory can be created with the
storage:ensure-directory command. This command will create a subdirectory in the recommended
/var/lib/dokku/data/storage path - created during Dokku installation - and prepare it for use with an app.
By default, permissions are set for usage with Herokuish buildpacks. These permissions can be changed via the
--chown option according to the following table:
--chown herokuish(default): Use
32767:32767as the folder permissions.
- This is used for apps deployed with Buildpacks via Herokuish.
--chown heroku: Use
1000:1000as the folder permissions.
- This is used for apps deployed with Cloud Native Buildpacks using the
--chown packeto: Use
2000:2000as the folder permissions.
- This is used for apps deployed with Cloud Native Buildpacks using the
--chown false: Skips the
Users deploying via Dockerfile will want to specify
--chown false and manually
chown the created directory if the user and/or group id of the runnning process in the deployed container do not correspond to any of the above options.
Failing to set the correct directory ownership may result in issues in persisting files written to the mounted storage directory.
Mounting storage into apps¶
Dokku supports mounting both explicit host paths as well as docker volumes via the
storage:mount command. This takes two arguments, an app name and a
# mount the directory into your container's /app/storage directory, relative to the container root (/) # explicit host paths _must_ exist prior to usage. dokku storage:mount node-js-app /var/lib/dokku/data/storage/node-js-app:/app/storage # mount the docker volume into your container's /app/storage directory, relative to the container root (/) # docker volumes _must_ exist prior to usage. dokku storage:mount node-js-app some-docker-volume:/app/storage
In the first example, Dokku will then mount the shared contents of
/app/storage inside the container. The mount point is not relative to your app's working directory, and is instead relative to the root (
/) of the container. Mounts are only available for containers created via
run and by the deploy process, and not during the build process. In addition, the host path is never auto-created by either Dokku or Docker, and should be an explicit path, not one relative to the current working directory.
/storage path within the container had pre-existing content, the container files will be over-written. This may be an issue for users that create assets at build time but then mount a directory at the same place during runtime. Files are not merged.
Once persistent storage is mounted, the app requires a restart. See the process scaling documentation for more information.
If an app no longer requires a mounted volume or directory, the
storage:unmount command can be called. This takes the same arguments as the
storage:mount command, an app name and a
# unmount the directory from your container's /app/storage directory, relative to the container root (/) dokku storage:unmount node-js-app /var/lib/dokku/data/storage/node-js-app:/app/storage # unmount the docker volume from your container's /app/storage directory, relative to the container root (/) dokku storage:unmount node-js-app some-docker-volume:/app/storage
Once persistent storage is unmounted, the app requires a restart. See the process scaling documentation for more information.
Displaying storage reports for an app¶
Introduced in 0.8.1
You can get a report about the app's storage status using the
=====> node-js-app storage information Storage build mounts: Storage deploy mounts: -v /var/lib/dokku/data/storage/node-js-app:/app/storage Storage run mounts: -v /var/lib/dokku/data/storage/node-js-app:/app/storage =====> python-sample storage information Storage build mounts: Storage deploy mounts: Storage run mounts: =====> ruby-sample storage information Storage build mounts: Storage deploy mounts: Storage run mounts:
You can run the command for a specific app also.
You can pass flags which will output only the value of the specific information you want. For example:
Sharing storage across deploys¶
Dokku is powered by Docker containers, which recommends in their best practices that containers be treated as ephemeral. In order to manage persistent storage for web apps, like user uploads or large binary assets like images, a directory outside the container should be mounted.
Shared storage between containers¶
When scaling your app, you may require a common location to access shared assets between containers, a storage mount can be used in this situation.
Shared storage across environments¶
Your app may be used in a cluster that requires containers or resources not running on the same host access your data. Mounting a shared file service (like S3FS or EFS) inside your container will give you great flexibility.
Your app may have services that are running in memory and need to be backed up locally (like a key store). Mount a non ephemeral storage mount will allow backups that are not lost when the app is shut down.
By default, Dokku will only bind storage mounts during the deploy and run phases. Under certain conditions, one might want to bind a storage mount during the build phase. This can be accomplished by using the
docker-options plugin directly.
You cannot use mounted volumes during the build phase of a Dockerfile deploy. This is because Docker does not support volumes when executing
This can cause data loss if you bind a mount under
/app in buildpack apps as herokuish will attempt to remove the original app path during the build phase.
App User and Persistent Storage file ownership (buildpack apps only)¶
Introduced in 0.7.1
By default, Dokku will execute your buildpack app processes as the
herokuishuser user. You may override this by setting the
DOKKU_APP_USER config variable.
NOTE: this user must exist in your herokuish image.
Additionally, the default
docker-local scheduler that comes with Dokku will ensure your storage mounts are owned by either
herokuishuser or the overridden value you have set in
DOKKU_APP_USER. See the docker-local scheduler documentation docs for more information.