.. _arch_overview_access_logs: Access logging ============== The :ref:`HTTP connection manager ` and :ref:`tcp proxy ` supports extensible access logging with the following features: * Any number of access logs per connection manager or tcp proxy. * Customizable access log filters that allow different types of requests and responses to be written to different access logs. Access logging sinks -------------------- Envoy supports pluggable access logging sinks. The currently supported sinks are: File **** * Asynchronous IO flushing architecture. Access logging will never block the main network processing threads. * Customizable access log formats using predefined fields as well as arbitrary HTTP request and response headers. gRPC **** * Envoy can send access log messages to a gRPC access logging service. Further reading --------------- * Access log :ref:`configuration `. * File :ref:`access log sink `. * gRPC :ref:`Access Log Service (ALS) ` sink.