Add a .ssh/config template

This serves two purposes: it is a placeholder for the SSH
configurations the user might want to add, and it also makes sure
that ~docker/.ssh/ exists so that a private key can be dropped into
authorized_keys.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a helper to connect to Xpra inside the Docker container

Images generated by 'docker commit' actually do not inherit the CMD.
Therefore, when we try to commit the private key into the image, we will
lose the default command.

We could now play nasty little sed games with the output of 'docker
inspect', but the better way is to use a shared directory (useful for data
exchange in any case) for the container to pick up the private key: that
way, the image will actually not contain any default private key (and
can therefore not be forgotten to be replaced).

We will keep the change here, however, for the historical record.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add the placeholder directory shared/

With the upcoming change to connect.sh, we will map said directory
automatically into the Docker image (as /shared/).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Use a better way to get authorized_keys installed

The previous attempt to commit the public ssh key into the image was
misguided: it asked for over-sharing of information.

Instead, let's just pick up the public key from the shared/ directory and
install it into $HOME/.ssh/authorized_keys upon container startup (via
docker-desktop).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
connect.sh: do not complain about unknown host key

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Get rid of startup.sh

We really can do almost all of it in the Dockerfile. The only thing we cannot do there is the password generation; The plan is to move away from the password anyway, in favor of a to-be-generated private/public key pair.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Switch to a seamless desktop

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Start the Xpra server when starting the container

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Start ssh daemon first and keep Xpra in the foreground

That way, if Xpra stops running, the container stops running, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Upgrade to saucy

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Avoid dpkg-divert hack

Apparently, it is no longer necessary now that we are starting dbus
correctly.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Adjust README

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>