> 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.
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:
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.
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 `host-path:container-path` or `docker-volume:container-path` combination.
In the first example, Dokku will then mount the shared contents of `/var/lib/dokku/data/storage/node-js-app` to `/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.
> If the `/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](/docs/processes/process-management.md) 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 `host-path:container-path` or `docker-volume:container-path` combination.
```shell
# unmount the directory from your container's /app/storage directory, relative to the container root (/)
Once persistent storage is unmounted, the app requires a restart. See the [process scaling documentation](/docs/processes/process-management.md) for more information.
Dokku is powered by Docker containers, which recommends in their [best practices](https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/#containers-should-be-ephemeral) 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.
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 `docker build`.
> **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.
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.
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/deployment/schedulers/docker-local.md#disabling-chown-of-persistent-storage) docs for more information.
