Source: https://github.com/matrix-org/synapse/blob/v1.59.0/docs/upgrade.md#deprecation-of-the-synapseappappservice-and-synapseappuser_dir-worker-application-types

As an alternative, we should probably find a way to run one or a few
more generic workers (which will handle appservice and user_dir stuff) and
update `homeserver.yaml` so that it would point to the name of these workers using
`notify_appservices_from_worker` and `update_user_directory_from_worker` options.

For now, this solves the deprecation, so we can have a peace of mind
going forward.

We're force-setting these worker counts to 0, so that we can clean up
existing homeservers which use these worker types. In the future, these
options will either be removed or repurposed (so that they transparently
create more generic workers that handle user_dir/appservice loads).

These endpoints should not be proxied to a generic Synapse worker
without other preparation (setting up stream writers, sending traffic
to a specific stream writer, etc.).

Disabling them for now. In the future, we'd like to fix up our awk
script to disable them automatically.

This is a fix up for 058fedff91

This prevented us from keeping our workers reverse-proxying definitions
updated since Synapse v1.54.0.

The last `workers.md` file we could parse is at commit
02632b3504.
Parsing regressed at commit c56bfb08bc071368db23f3b1c593724eb4f205f0,
because the introduction message for `synapse.app.generic_worker` said
"If":

> If a worker is set up to handle a..

.. which made the AWK script think that definitions below were
conditional (which they're not in this case).

This patch fixes up the regex for determining if a line is conditional
or not, so that it doesn't trip up. Hopefully, it doesn't miss something
important.

1472958e25 reverted some of the v3 changes. I'm not sure why. Running the `workers-doc-to-yaml.sh` script now puts them back 🤷‍♂️.

We had to remove UID/GID environment variables that we used to pass
to the Synapse container, because it was causing a problem after
https://github.com/matrix-org/synapse/pull/11209

We were using both `--user` and UID/GID environment variables until now.

1f196f59cb

Related to:

- https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1287
- https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1288

.. but does it in a more complete way

Should have been part of 9daeb39710

I guess it didn't hurt to do it until now, but it's not great serving
federation APIs on the client-server API port, etc.

matrix-corporal doesn't work yet (still something to be solved in the
future), but its firewalling operations will also be sabotaged
by Client-Server APIs being served on the federation port (it's a way to get around its firewalling).

Fixes #523 (Github Issue).

The goal is to move each bridge into its own separate role.
This commit starts off the work on this with 2 bridges:
- mautrix-telegram
- mautrix-whatsapp

Each bridge's role (including these 2) is meant to:

- depend only on the matrix-base role

- integrate nicely with the matrix-synapse role (if available)

- integrate nicely with the matrix-nginx-proxy role (if available and if
required). mautrix-telegram bridge benefits from integrating with
it.

- not break if matrix-synapse or matrix-nginx-proxy are not used at all

This has been provoked by #174 (Github Issue).

With this change, the following roles are now only dependent
on the minimal `matrix-base` role:
- `matrix-corporal`
- `matrix-coturn`
- `matrix-mailer`
- `matrix-mxisd`
- `matrix-postgres`
- `matrix-riot-web`
- `matrix-synapse`

The `matrix-nginx-proxy` role still does too much and remains
dependent on the others.

Wiring up the various (now-independent) roles happens
via a glue variables file (`group_vars/matrix-servers`).
It's triggered for all hosts in the `matrix-servers` group.

According to Ansible's rules of priority, we have the following
chain of inclusion/overriding now:
- role defaults (mostly empty or good for independent usage)
- playbook glue variables (`group_vars/matrix-servers`)
- inventory host variables (`inventory/host_vars/matrix.<your-domain>`)

All roles default to enabling their main component
(e.g. `matrix_mxisd_enabled: true`, `matrix_riot_web_enabled: true`).
Reasoning: if a role is included in a playbook (especially separately,
in another playbook), it should "work" by default.

Our playbook disables some of those if they are not generally useful
(e.g. `matrix_corporal_enabled: false`).