feat(cmdeploy): add ssh_host chatmail.ini option to deploy remotely, recommend localhost deployment as default

[missytake]

pyinfra, stemming from ansible, has a build machine / deployment server separation which we don't actually need in this project. We are mostly using it to script the installation, not to document our deployment; and I don't know of anyone importing cmdeploy as a pyinfra deployment module (other than https://github.com/deltachat/pyinfra-borgbackup/ for example).

Let's make it easier for future operators by simply assuming that you install cmdeploy on the relay itself. This also helps with people having weird laptop OSes.

The idea is to add a chatmail.ini config parameter, ssh_host, which will be set to "localhost" on cmdeploy init to be the default for new operators, but which will default to mail_domain if unset, so existing deployments keep working with their chatmail.ini files. This could become a problem if some is used to setup chatmail relays remotely without keeping the chatmail.ini file around, though.

[hpk42]

is this PR still needed?

[missytake]

is this PR still needed?

I still think it is a great improvement, but it's not a priority for the first half of May. I'll continue to work on it in a few weeks

[missytake]

cmlxc fails, because the default now says to deploy in the builder container. Should we change cmlxc to deploy on the relay itself, or remove the ssh_host option in the generated chatmail.ini?

I'll proceed with hardcoding the ssh_host option to mail_domain for now.

[j-g00da]

LGTM, left some nits

[j-g00da]

I'm still a bit worried, this will confuse some people (although, it indeed makes more sense).

[missytake]

Yeah, I couldn't come up with a better path forward. If you have a better wording, let me work :)

[j-g00da]

It's mostly confusing because mail_domain is the default... except it's not because it is also overwritten by default by localhost.

Maybe something like:

Suggested change

	# Where to deploy the relay - if unspecified, mail_domain will be used.
	ssh_host = localhost
	# Where to deploy the relay.
	# Change the following line to deploy on a remote machine instead,
	# or remove it to deploy on mail_domain.

Not sure :/

[j4n]

lgtm :) we've been deploying nine like this for a while and its just much faster in the very least.

[missytake]

I started a small poll in the operators community to see if this breaks anyone's workflows or is viewed critically in any way.

[missytake]

The change is not uncontroversial:

Let's talk about it next week.