HTTP access logging

You can configure access log settings for HTTP endpoints. An HTTP access log contains a record of all inbound client requests that are handled by HTTP endpoints.

You can enable access logging in the Open Liberty Server in two modes, a single log for multiple endpoints or one log for each endpoint. If you do not specify attributes, the defaults are used. To see a list of the default attributes, see httpAccessLogging.

HTTP access log settings

You can configure HTTP access log settings either for multiple endpoints that share common log settings or for individual endpoints.

Settings for a common log

To enable logging for multiple endpoints with common settings, include httpAccessLogging as a top-level element in your server.xml file. Reference this element from multiple httpEndpoint elements, as shown in the following example.

<httpAccessLogging id="accessLogging"/>
<httpEndpoint id="defaultHttpEndpoint" accessLoggingRef="accessLogging" httpPort="9080" httpsPort="9443"/>
<httpEndpoint id="otherHttpEndpoint" accessLoggingRef="accessLogging" httpPort="9081" httpsPort="9444"/>

Settings for distinct logs for each endpoint

To enable logging for individual endpoints, use an accessLogging child element and specify a file path that does not conflict with other logs, as shown in the following example.

<httpEndpoint id="defaultHttpEndpoint" httpPort="9080" httpsPort="9443">
    <accessLogging filepath="${server.output.dir}/logs/http_defaultEndpoint_access.log"/>
</httpEndpoint>

HTTP access log format

Use the accessLogFormat property to specify the information and format you want to include in the NCSA access log for an HTTP transport channel. The value for this property is a space-separated list of options.

Specify the log format string with the logFormat attribute of httpAcccessLogging or accessLogging elements in the server.xml file, as shown in the following examples.

In the following server.xml file example, The logformat attribute for the httpAcccessLogging element specifies the log format string. Multiple endpoints can specify this string by referencing the accessLogging configuration ID.

<httpAccessLogging id="accessLogging" logFormat='%h %u %{t}W "%r" %s %b %D %{R}W'/>

In the following server.xml file example, the logformat attribute for the accessLogging subelement specifies the log format string for a specific endpoint that is defined in the httpEndpoint element.

<httpEndpoint id="defaultHttpEndpoint" httpPort="9080" httpsPort="9443">
   <accessLogging filepath="${server.output.dir}/logs/http_defaultEndpoint_access.log"
                  logFormat='%h %i %u %t "%r" %s %b %D %{R}W' />
</httpEndpoint>

The following table lists the available log format options.

Log format option Description

Log format option	Description
%a	The remote IP address
%A	The local IP address
%b	The response size in bytes excluding the headers
%B	The response size in bytes excluding the headers. If no value is found, `0` is printed instead of `-`.
%{CookieName}C or %C	The request cookie that is specified within the brackets. If the brackets are not included, print all of the request cookies.
%D	The elapsed time of the request, in microseconds
%h	The remote host
%i or %{HeaderName}i	The `HeaderName` header value from the request
%m	The request method
%o or %{HeaderName}o	The `HeaderName` header value from the response
%q	Output the query string with any password masked
%r	The first line of the request
%{remote}p	The ephemeral port of the client that made the request
%{R}W	Service time of the request from the moment the request is received until the first set of bytes of the response is sent - millisecond accuracy, microsecond precision
%s	The status code of the response
%t	The start time of the request, in NCSA format
%{t}W	The end time of the request, in NCSA format
%u	The remote user according to the Open Liberty-specific `$WSRU` header
%U	The URL Path, not including the query string

The remote IP address

The local IP address

The response size in bytes excluding the headers

The response size in bytes excluding the headers. If no value is found, 0 is printed instead of -.

%{CookieName}C or %C

The request cookie that is specified within the brackets. If the brackets are not included, print all of the request cookies.

The elapsed time of the request, in microseconds

The remote host

%i or %{HeaderName}i

The HeaderName header value from the request

The request method

%o or %{HeaderName}o

The HeaderName header value from the response

Output the query string with any password masked

The first line of the request

%{remote}p

The ephemeral port of the client that made the request

%{R}W

Service time of the request from the moment the request is received until the first set of bytes of the response is sent - millisecond accuracy, microsecond precision

The status code of the response

The start time of the request, in NCSA format

%{t}W

The end time of the request, in NCSA format

The remote user according to the Open Liberty-specific $WSRU header

The URL Path, not including the query string

Each option can be enclosed in quotation marks, but the quotation marks are not required. Unless otherwise noted, a value of - is printed for an option if the requested information cannot be obtained for that option.

The order that you specify the options determines the format of this information in the log. For example, you might specify the following directives as the value for the accessLogFormat property:

 %h %i %u %t "%r" %s %b %D %{R}W

Based on this setting, the NCSA access log includes the following information for each request in the specified order:

The remote host
The HeaderName header value from the request
The remote user according to the WebSphere Specific $WSRU header
The NCSA format of the start time of the request
The first line of the request
The status code of the response
The response size in bytes excluding headers
The elapsed time of the request in microseconds, end-to-end, including client and network time
The elapsed time in microseconds until the first bytes of the response are sent. This value is often a close approximation of application response time.

Time-based HTTP access log rollover

You can enable time-based periodic rollover of your HTTP access log file by specifying a log rollover start time and a log rollover interval duration. The specified rollover start time is the time of day when the HTTP access log file first rolls over. The rollover interval duration is the time interval between consecutive HTTP access log file rollovers.

For example, a server with a rollover start time of midnight and a rollover interval of 1 day rolls over the HTTP access log once every day, at midnight.

Enable time-based rollover of your HTTP access log file by using the rolloverStartTime and rolloverInterval attributes of the httpAcccessLogging or accessLogging elements in the server.xml file. The following table lists the two attributes, their respective descriptions, and their permitted values.

Time-based log rollover attribute Description

Time-based log rollover attribute	Description
`rolloverStartTime`	Use this setting alone or with the `rolloverInterval` attribute to enable time-based log rollover for your HTTP access log file. This setting specifies the scheduled time of day for logs to first roll over. The `rolloverInterval` setting duration begins at `rolloverStartTime`. Valid values follow a 24-hour ISO-8601 date-time format of HH:MM, where 00:00 represents midnight. Padding zeros are required. If the `rolloverInterval` attribute is specified, the default value of the `rolloverStartTime` attribute is 00:00, midnight.
`rolloverInterval`	Use this setting alone or with the `rolloverStartTime` attribute to enable time-based log rollover for your HTTP access log file. This setting specifies the time interval in between log rollovers, in minutes if a unit of time is not specified. Specify a positive integer followed by a unit of time, which can be days (d), hours (h), or minutes (m). For example, specify 5 hours as 5h. You can include multiple values in a single entry. For example, 1d5h is equivalent to 1 day and 5 hours. If the `rolloverStartTime` attribute is specified, the default value of the `rolloverInterval` attribute is 1 day.

rolloverStartTime

Use this setting alone or with the rolloverInterval attribute to enable time-based log rollover for your HTTP access log file. This setting specifies the scheduled time of day for logs to first roll over. The rolloverInterval setting duration begins at rolloverStartTime. Valid values follow a 24-hour ISO-8601 date-time format of HH:MM, where 00:00 represents midnight. Padding zeros are required. If the rolloverInterval attribute is specified, the default value of the rolloverStartTime attribute is 00:00, midnight.

rolloverInterval

Use this setting alone or with the rolloverStartTime attribute to enable time-based log rollover for your HTTP access log file. This setting specifies the time interval in between log rollovers, in minutes if a unit of time is not specified. Specify a positive integer followed by a unit of time, which can be days (d), hours (h), or minutes (m). For example, specify 5 hours as 5h. You can include multiple values in a single entry. For example, 1d5h is equivalent to 1 day and 5 hours. If the rolloverStartTime attribute is specified, the default value of the rolloverInterval attribute is 1 day.

The following examples demonstrate how to enable time-based periodic rollover for the HTTP access log file in the httpAcccessLogging and accessLogging elements. The rolloverStartTime attribute is set to midnight and the rolloverInterval attribute is set to 1 day.

In the following server.xml file example, the rolloverStartTime and rolloverInterval attributes for the httpAcccessLogging element specify the log rollover start time and interval for multiple endpoints that reference the accessLogging configuration ID.

<httpAccessLogging id="accessLogging`" rolloverStartTime="00:00" rolloverInterval="1d"/>

In the following server.xml file example, attributes for the accessLogging subelement specify configuration for a specific endpoint that is defined in the httpEndpoint element. The rolloverStartTime and rolloverInterval attributes specify the log rollover start time and interval for the endpoint.

<httpEndpoint id="defaultHttpEndpoint" httpPort="9080" httpsPort="9443">
   <accessLogging filepath="${server.output.dir}/logs/http_defaultEndpoint_access.log"
                 rolloverStartTime="00:00" rolloverInterval="1d" />
</httpEndpoint>