Smb support unavailable in docker container even from "full" image

Note: I am duplicating the contents of a Github issue with the same name, in case doing so generates some useful discussion about a resolution.

I am seeking to launch a Docker container on an embedded target, in particular a NAS, with inclusion of an SMB/CIFS client, for external storage.

I am new to Docker, but have done my best to find appropriate background resources to resolve a path for provisioning the container. Among these resources is the examples documentation.

My approach has been the following steps:

  1. On a desktop Linux system, of matching machine architecture, invoke the following commands:
$ docker build
$ docker save nextcloud -o nextcloud-full-apache.tar
  1. Import the image given in the resulting tarball, nextcloud-full-apache.tar, into the target system.
  2. Launch a container from the image.

Unfortunately, after establishing the Nextcloud instance on the target system, the following message is shown in the External storage page:

“smbclient” is not installed. Mounting of “SMB/CIFS”, “SMB/CIFS using OC login” is not possible. Please ask your system administrator to install it.

This message is the same as had appeared when running from the image distributed through the Docker hub.

The expectation had been that the image built from the repository, described as a “full” image, would contain the SMB client components.

Perhaps I am misunderstanding some essential attribute of the Docker workflow. In any case, I am grateful for any support available, and I would try to assist providing any further details that may help resolve whether my observations reflect any issues in the repository for the Nextcloud Docker image.