Merge pull request #3256 from matrix-org/3218-official-prom

.gitignore

synapse/api/auth.py

synapse/app/homeserver.py

synapse/federation/federation_client.py

synapse/federation/federation_server.py

synapse/federation/send_queue.py

synapse/federation/transaction_queue.py

synapse/handlers/appservice.py

synapse/handlers/presence.py

synapse/http/client.py

synapse/http/matrixfederationclient.py

synapse/http/request_metrics.py

synapse/http/server.py

synapse/http/site.py

synapse/metrics/__init__.py

synapse/metrics/metric.py

synapse/metrics/process_collector.py

synapse/metrics/resource.py

synapse/notifier.py

synapse/push/bulk_push_rule_evaluator.py