* Presentation

This charm allows you to host a SFTP (using ssh) with it's own user
database. They can be authenticated with a password or with a SSH key.

You can choose exactly what data will be accessible to them by mount
binding each directory you want to share from the host in their own
home directory in the container. (see the examples).

The permissions should be managed through group permissions, directly
from the host and in the shared directory.

Each user in the container will be part of multiple groups
(configurable via the options of the charm in your service definition
of the =compose.yml=), and the GID of the groups will be the same on
the host and on the container.

* Example configuration

#+begin_src yaml
  sftp:
    docker-compose:
      ports:
        - "10622:22"
      volumes:
        ## Here we allow access to specific directories only by binding
        ## them in their home directory:
        - /srv/datastore/data/www/var/www/www.myclientwebsite.com:/home/myclient1/www.myclientwebsite.com:rw
        - /srv/datastore/data/www/var/www/www.myclientwebsite.com:/home/myclient2/www.myclientwebsite.com:rw
    options:
      users:
        myclient1:
          ## These groups are created on the container with the given GID
          ## Note that UID/GID are the same for the container and the host,
          ## So don't forget to give the appropriate rights from the host on
          ## the shared directory to ensure that access is effectively granted
          ## as you want to the customer
          groups:
            - sftpaccess-rw:3000
          password: FaKePaSSw0rdT0Ch4Ng3
          keys:
            - "ssh-rsa AAAAB3NzaC2yc2Z..."
        myclient2:
          ## These groups are created on the container with the given GID
          ## Note that UID/GID are the same for the container and the host,
          ## So don't forget to give the appropriate rights from the host on
          ## the shared directory to ensure that access is effectively granted
          ## as you want to the customer
          groups:
            - sftpaccess-rw:3000
          password: FaKePaSSw0rdT0Ch4Ng3
          keys:
            - "ssh-rsa AAAAB3NzBC1yc2X..."
#+end_src


In this case, you'll need also to make sure to set up correctly the
directories you shared, in this example, only
=/srv/datastore/data/www/var/www/www.myclientwebsite.com= is shared :
you are expected to set the permissions of the group identified by the
id `3000`.

Using getfacl/setfacl is the right tool most of the time. If you don't
have it:

#+begin_src sh
apt-get install acl
#+end_src

Then, you could:

#+begin_src sh
find /srv/datastore/data/www/var/www/www.myclientwebsite.com -type d \
    -exec getfacl -mR d:g:3000:rwx,d:g:3000:rwx
#+end_src