.. _config_application_logs: Application logging =================== Envoy and its filters write application logs for debuggability. Envoy can be configured to output application logs in a format that is compatible with common log viewers. This section documents how Envoy can be configured to enable integration with each log viewer. Stackdriver Logging with GKE ---------------------------- `Stackdriver Logging `_ can read logs from containers running on `Google Kubernetes Engine `_. Envoy should be configured with the following :ref:`command line options `: * ``--log-format '%L%m%d %T.%e %t envoy/%@] [%t][%n]%v'``: Logs are formatted in `glog `_ format, allowing Stackdriver to parse the log severity and timestamp. * ``--log-format-escaped``: Each string that is logged will be printed in a single line. C-style escape sequences (such as ``\n``) will be escaped and prevent a single string from spanning multiple lines. This ensures each log line is structured with the glog prefix. * The ``--log-path`` flag **does not** need to be set, since Stackdriver can read logs from STDERR. * The ``--log-level`` flag can be set to control the log severity logged to Stackdriver. `Reference documentation `_ for Stackdriver on GKE.