The Entry Log Valve helps the next
configuration attributes:

Attribute	Description
buffered	Flag to find out if logging will likely be buffered. If set to false, then entry logging will likely be written after every request. Default worth: true
className	Java class identify of the implementation to make use of. This MUST be set to org.apache.catalina.valves.AccessLogValve to make use of the default entry log valve.
situation	The identical as conditionUnless. This attribute is supplied for backwards compatibility.
conditionIf	Activates conditional logging. If set, requests will likely be logged provided that ServletRequest.getAttribute() is not null. For instance, if this worth is ready to vital, then a specific request will solely be logged if ServletRequest.getAttribute("important") != null. The usage of Filters is a straightforward option to set/unset the attribute within the ServletRequest on many various requests.
conditionUnless	Activates conditional logging. If set, requests will likely be logged provided that ServletRequest.getAttribute() is null. For instance, if this worth is ready to junk, then a specific request will solely be logged if ServletRequest.getAttribute("junk") == null. The usage of Filters is a straightforward option to set/unset the attribute within the ServletRequest on many various requests.
listing	Absolute or relative pathname of a listing through which log recordsdata created by this valve will likely be positioned. If a relative path is specified, it’s interpreted as relative to $CATALINA_BASE. If no listing attribute is specified, the default worth is “logs” (relative to $CATALINA_BASE).
encoding	Character set used to put in writing the log file. An empty string means to make use of the system default character set. Default worth: use the system default character set.
fileDateFormat	Permits a personalized timestamp within the entry log file identify. The file is rotated every time the formatted timestamp modifications. The default worth is yyyy-MM-dd. Should you want to rotate each hour, then set this worth to yyyy-MM-dd.HH. The date format will all the time be localized utilizing the locale en_US.
locale	The locale used to format timestamps within the entry log traces. Any timestamps configured utilizing an express SimpleDateFormat sample (%{xxx}t) are formatted on this locale. By default the default locale of the Java course of is used. Switching the locale after the AccessLogValve is initialized will not be supported. Any timestamps utilizing the widespread log format (CLF) are all the time formatted within the locale en_US.
maxDays	The utmost variety of days rotated entry logs will likely be retained for earlier than being deleted. If not specified, the default worth of -1 will likely be used which implies by no means delete outdated recordsdata.
sample	A formatting structure figuring out the assorted info fields from the request and response to be logged, or the phrase widespread or mixed to pick out a customary format. See beneath for extra info on configuring this attribute.
prefix	The prefix added to the beginning of every log file’s identify. If not specified, the default worth is “access_log”.
renameOnRotate	By default for a rotatable log the energetic entry log file identify will include the present timestamp in fileDateFormat. Throughout rotation the file is closed and a brand new file with the subsequent timestamp within the identify is created and used. When setting renameOnRotate to true, the timestamp is now not a part of the energetic log file identify. Solely throughout rotation the file is closed after which renamed to incorporate the timestamp. That is just like the habits of most log frameworks when doing time based mostly rotation. Default worth: false
requestAttributesEnabled	Set to true to examine for the existence of request attributes (usually set by the RemoteIpValve and related) that ought to be used to override the values returned by the request for distant deal with, distant host, server port and protocol. If the attributes are not set, or this attribute is ready to false then the values from the request will likely be used. If not set, the default worth of false will likely be used.
resolveHosts	This attribute is now not supported. Use the connector attribute enableLookups as an alternative. You probably have enableLookups on the connector set to true and wish to ignore it, use %a as an alternative of %h within the worth of sample.
rotatable	Flag to find out if log rotation ought to happen. If set to false, then this file isn’t rotated and fileDateFormat is ignored. Default worth: true
suffix	The suffix added to the tip of every log file’s identify. If not specified, the default worth is ” (a zero-length string), that means that no suffix will likely be added.

Values for the sample attribute are made up of literal
textual content strings, mixed with sample identifiers prefixed by the “%”
character to trigger alternative by the corresponding variable worth from
the present request and response. The next sample codes are
supported:

• %a – Distant IP deal with
• %A – Native IP deal with
• %b – Bytes despatched, excluding HTTP headers, or ‘-‘ if zero
• %B – Bytes despatched, excluding HTTP headers
• %h – Distant host identify (or IP deal with if
  enableLookups for the connector is fake)
• %H – Request protocol
• %l – Distant logical username from identd (all the time returns
  ‘-‘)
• %m – Request methodology (GET, POST, and so on.)
• %p – Native port on which this request was acquired.
  See additionally %{xxx}p beneath.
• %q – Question string (prepended with a ‘?’ if it exists)
• %r – First line of the request (methodology and request URI)
• %s – HTTP standing code of the response
• %S – Person session ID
• %t – Date and time, in Widespread Log Format
• %u – Distant person that was authenticated (if any), else ‘-‘
• %U – Requested URL path
• %v – Native server identify
• %D – Time taken to course of the request in millis. Be aware: In
  httpd %D is microseconds. Behaviour will likely be aligned to httpd
  in Tomcat 10 onwards.
• %T – Time taken to course of the request, in seconds. Be aware: This
  worth has millisecond decision whereas in httpd it has
  second decision. Behaviour will likely be align to httpd
  in Tomcat 10 onwards.
• %F – Time taken to commit the response, in millis
• %I – Present request thread identify (can evaluate later with stacktraces)

There may be additionally assist to put in writing info incoming or outgoing
headers, cookies, session or request attributes and particular
timestamp codecs.
It’s modeled after the
Apache HTTP Server log configuration
syntax. Every of them can be utilized a number of instances with completely different xxx keys:

• %{xxx}i write worth of incoming header with identify xxx
• %{xxx}o write worth of outgoing header with identify xxx
• %{xxx}c write worth of cookie with identify xxx
• %{xxx}r write worth of ServletRequest attribute with identify xxx
• %{xxx}s write worth of HttpSession attribute with identify xxx
• %{xxx}p write native (server) port (xxx==native) or
  distant (shopper) port (xxx=distant)
• %{xxx}t write timestamp on the finish of the request formatted utilizing the
  enhanced SimpleDateFormat sample xxx

All codecs supported by SimpleDateFormat are allowed in %{xxx}t.
As well as the next extensions have been added:

• sec – variety of seconds for the reason that epoch
• msec – variety of milliseconds for the reason that epoch
• msec_frac – millisecond fraction

These codecs can’t be blended with SimpleDateFormat codecs in the identical format
token.

Moreover one can outline whether or not to log the timestamp for the request begin
time or the response end time:

• start or prefix start: chooses
  the request begin time
• finish or prefix finish: chooses
  the response end time

By including a number of %{xxx}t tokens to the sample, one can
additionally log each timestamps.

The shorthand sample sample="common"
corresponds to the Widespread Log Format outlined by
‘%h %l %u %t “%r” %s %b’.

The shorthand sample sample="combined"
appends the values of the Referer and Person-Agent
headers, every in double quotes, to the widespread sample.

When Tomcat is working behind a reverse proxy, the shopper info
logged by the Entry Log Valve could symbolize the reverse proxy, the browser
or some mixture of the 2 relying on the configuration of Tomcat and
the reverse proxy. For Tomcat configuration choices see
Proxies Assist and the
Proxy How-To. For reverse proxies that
use mod_jk, see the generic
proxy documentation. For different reverse proxies, seek the advice of their
documentation.