Clean up worker.yaml generation a bit and make it more flexible

roles/matrix-synapse/defaults/main.yml

@@ -333,7 +333,16 @@ matrix_synapse_redis_host: ""
 matrix_synapse_redis_port: 6379
 matrix_synapse_redis_password: ""
 
-# Port used for communication between main synapse process and workers
+# Controls whether Synapse starts a replication listener necessary for workers.
+#
+# If Redis is available, we prefer to use that, instead of talking over Synapse's custom replication protocol.
+#
+# matrix_synapse_replication_listener_enabled: "{{ matrix_synapse_workers_enabled and not matrix_redis_enabled }}"
+# We force-enable this listener for now until we debug why communication via Redis fails.
+matrix_synapse_replication_listener_enabled: true
+
+# Port used for communication between main synapse process and workers.
+# Only gets used if `matrix_synapse_replication_listener_enabled: true`
 matrix_synapse_replication_http_port: 9093
 
 # Send ERROR logs to sentry.io for easier tracking

roles/matrix-synapse/templates/synapse/homeserver.yaml.j2

@@ -277,6 +277,8 @@ listeners:
 {% endif %}
 
 {% if matrix_synapse_workers_enabled %}
+
+{% if matrix_synapse_replication_listener_enabled %}
   # c.f. https://github.com/matrix-org/synapse/tree/master/docs/workers.md
   # HTTP replication: for the workers to send data to the main synapse process
   - port: {{ matrix_synapse_replication_http_port }}
@@ -284,6 +286,7 @@ listeners:
     type: http
     resources:
       - names: [replication]
+{% endif %}
 
 # c.f. https://github.com/matrix-org/synapse/tree/master/contrib/systemd-with-workers/README.md
 worker_app: synapse.app.homeserver

roles/matrix-synapse/templates/synapse/worker.yaml.j2

@@ -2,30 +2,40 @@
 worker_app: synapse.app.{{ matrix_synapse_worker_details.type }}
 worker_name: {{ matrix_synapse_worker_details.type ~ ':' ~ matrix_synapse_worker_details.port }}
 
+{% if matrix_synapse_replication_listener_enabled %}
 worker_replication_host: matrix-synapse
 worker_replication_http_port: {{ matrix_synapse_replication_http_port }}
+{% endif %}
 
+{% set has_listeners = (matrix_synapse_worker_details.type not in [ 'appservice', 'federation_sender', 'pusher' ] or matrix_synapse_metrics_enabled) %}
+
+{% set http_resources = [] %}
+
+{% if matrix_synapse_worker_details.type in ['generic_worker', 'frontend_proxy', 'user_dir'] %}
+  {% set http_resources = http_resources + ['client'] %}
+{% endif %}
+{% if matrix_synapse_worker_details.type in ['generic_worker'] %}
+  {% set http_resources = http_resources+ ['federation'] %}
+{% endif %}
+{% if matrix_synapse_worker_details.type in ['media_repository'] %}
+  {% set http_resources = http_resources + ['media'] %}
+{% endif %}
+
+{% if http_resources|length > 0 or matrix_synapse_metrics_enabled %}
 worker_listeners:
-{% if matrix_synapse_worker_details.type not in [ 'appservice', 'federation_sender', 'pusher' ] %}
+{% if http_resources|length > 0 %}
   - type: http
     bind_addresses: ['::']
     port: {{ matrix_synapse_worker_details.port }}
     resources:
-      - names:
-{% if matrix_synapse_worker_details.type in [ 'generic_worker', 'frontend_proxy', 'user_dir' ] %}
-        - client
-{% endif %}
-{% if matrix_synapse_worker_details.type in [ 'generic_worker' ] %}
-        - federation
-{% elif matrix_synapse_worker_details.type in [ 'media_repository' ] %}
-        - media
-{% endif %}
+      - names: {{ http_resources|to_json }}
 {% endif %}
 {% if matrix_synapse_metrics_enabled %}
   - type: metrics
     bind_addresses: ['::']
     port: {{ matrix_synapse_worker_details.metrics_port }}
 {% endif %}
+{% endif %}
 
 {% if matrix_synapse_worker_details.type == 'frontend_proxy' %}
 worker_main_http_uri: http://matrix-synapse:8008