Access logging

Configuration

Access logs are configured as part of the HTTP connection manager config or TCP Proxy.

Format rules

The access log format string contains either command operators or other characters interpreted as a plain string. The access log formatter does not make any assumptions about a new line separator, so one has to specified as part of the format string. See the default format for an example. Note that the access log line will contain a ‘-‘ character for every not set/empty value.

The same format strings are used by different types of access logs (such as HTTP and TCP). Some fields may have slightly different meanings, depending on what type of log it is. Differences are noted.

The following command operators are supported:

%START_TIME%
HTTP
Request start time including milliseconds.
TCP
Downstream connection start time including milliseconds.
%BYTES_RECEIVED%
HTTP
Body bytes received.
TCP
Downstream bytes received on connection.
%PROTOCOL%
HTTP
Protocol. Currently either HTTP/1.1 or HTTP/2.
TCP
Not implemented (“-“).
%RESPONSE_CODE%
HTTP
HTTP response code. Note that a response code of ‘0’ means that the server never sent the beginning of a response. This generally means that the (downstream) client disconnected.
TCP
Not implemented (“-“).
%BYTES_SENT%
HTTP
Body bytes sent.
TCP
Downstream bytes sent on connection.
%DURATION%
HTTP
Total duration in milliseconds of the request from the start time to the last byte out.
TCP
Total duration in milliseconds of the downstream connection.
%RESPONSE_FLAGS%

Additional details about the response or connection, if any. For TCP connections, the response codes mentioned in the descriptions do not apply. Possible values are:

HTTP and TCP
  • UH: No healthy upstream hosts in upstream cluster in addition to 503 response code.
  • UF: Upstream connection failure in addition to 503 response code.
  • UO: Upstream overflow (circuit breaking) in addition to 503 response code.
  • NR: No route configured for a given request in addition to 404 response code.
HTTP only
  • LH: Local service failed health check request in addition to 503 response code.
  • UT: Upstream request timeout in addition to 504 response code.
  • LR: Connection local reset in addition to 503 response code.
  • UR: Upstream remote reset in addition to 503 response code.
  • UC: Upstream connection termination in addition to 503 response code.
  • DI: The request processing was delayed for a period specified via fault injection.
  • FI: The request was aborted with a response code specified via fault injection.
  • RL: The request was ratelimited locally by the HTTP rate limit filter in addition to 429 response code.
%UPSTREAM_HOST%
Upstream host URL (e.g., tcp://ip:port for TCP connections).
%UPSTREAM_CLUSTER%
Upstream cluster to which the upstream host belongs to.
%UPSTREAM_LOCAL_ADDRESS%
Local address of the upstream connection. If the address is an IP address it includes both address and port.
%DOWNSTREAM_ADDRESS%

Remote address of the downstream connection without IP port if the address is an IP address.

Attention

This field is deprecated. Use DOWNSTREAM_REMOTE_ADDRESS or DOWNSTREAM_REMOTE_ADDRESS_WITHOUT_PORT instead.

%DOWNSTREAM_REMOTE_ADDRESS%

Remote address of the downstream connection. If the address is an IP address it includes both address and port.

Note

This may not be the physical remote address of the peer if the address has been inferred from proxy proto or x-forwarded-for.

%DOWNSTREAM_REMOTE_ADDRESS_WITHOUT_PORT%

Remote address of the downstream connection. If the address is an IP address the output does not include port.

Note

This may not be the physical remote address of the peer if the address has been inferred from proxy proto or x-forwarded-for.

%DOWNSTREAM_LOCAL_ADDRESS%
Remote address of the downstream connection. If the address is an IP address it includes both address and port.
%REQ(X?Y):Z%
HTTP
An HTTP request header where X is the main HTTP header, Y is the alternative one, and Z is an optional parameter denoting string truncation up to Z characters long. The value is taken from the HTTP request header named X first and if it’s not set, then request header Y is used. If none of the headers are present ‘-‘ symbol will be in the log.
TCP
Not implemented (“-“).
%RESP(X?Y):Z%
HTTP
Same as %REQ(X?Y):Z% but taken from HTTP response headers.
TCP
Not implemented (“-“).

Default format

If custom format is not specified, Envoy uses the following default format:

[%START_TIME%] "%REQ(:METHOD)% %REQ(X-ENVOY-ORIGINAL-PATH?:PATH)% %PROTOCOL%"
%RESPONSE_CODE% %RESPONSE_FLAGS% %BYTES_RECEIVED% %BYTES_SENT% %DURATION%
%RESP(X-ENVOY-UPSTREAM-SERVICE-TIME)% "%REQ(X-FORWARDED-FOR)%" "%REQ(USER-AGENT)%"
"%REQ(X-REQUEST-ID)%" "%REQ(:AUTHORITY)%" "%UPSTREAM_HOST%"\n

Example of the default Envoy access log format:

[2016-04-15T20:17:00.310Z] "POST /api/v1/locations HTTP/2" 204 - 154 0 226 100 "10.0.35.28"
"nsq2http" "cc21d9b0-cf5c-432b-8c7e-98aeb7988cd2" "locations" "tcp://10.0.2.1:80"