Enable sentry.io integration

roles/matrix-synapse/defaults/main.yml

@@ -205,6 +205,12 @@ matrix_synapse_url_preview_enabled: true
 matrix_synapse_metrics_enabled: false
 matrix_synapse_metrics_port: 9100
 
+# Send ERROR logs to sentry.io for easier tracking
+# To set this up: go to sentry.io, create a python project, and set
+# matrix_synapse_sentry_dsn to the URL it gives you.
+# See https://github.com/matrix-org/synapse/issues/4632 for important privacy concerns
+matrix_synapse_sentry_dsn: ""
+
 # Postgres database information
 matrix_synapse_database_host: ""
 matrix_synapse_database_user: ""

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

@@ -872,8 +872,10 @@ enable_metrics: {{ matrix_synapse_metrics_enabled|to_json  }}
 # information, and it in turn may then diseminate sensitive information
 # through insecure notification channels if so configured.
 #
-#sentry:
-#    dsn: "..."
+{% if matrix_synapse_sentry_dsn != "" %}
+sentry:
+    dsn: {{ matrix_synapse_sentry_dsn|to_json }}
+{% endif %}
 
 # Whether or not to report anonymized homeserver usage statistics.
 report_stats: {{ matrix_synapse_report_stats|to_json }}