Resin can perform access logging, specify where JDK logging interface messages go, and redirect the stderr and stdout for your applications.

Log Configuration Tags

stdout-log

Configure the destination for System.out.

Usage of the stdout-log overrides a previous usage. For example, specifying stdout-log as a child of a web-app causes a redirection of System.out for that web application only, and will override the System.out location in the enclosing host.

The default archive format is

path + ".%Y%m%d" or
  path + ".%Y%m%d.%H" if rollover-period < 1 day.

The following example configures System.out for a host. Unless a web-app overrides with it's own stdout-log, all web-apps in the host will write to the same output file.

...
<host id='foo.com'>
  <stdout-log path='/var/log/foo/stdout.log'
              rollover-period='1W'/>
  ...
</host>
...
  

stderr-log

Configure the destination for System.err.

Usage of the stderr-log overrides a previous usage. For example, specifying stderr-log as a child of a web-app causes a redirection of System.err for that web application only, and will override the System.err location in the enclosing host.

The default archive format is

path + ".%Y%m%d" or
  path + ".%Y%m%d.%H" if rollover-period < 1 day.

The following example configures System.err for a host. Unless a web-app overrides with it's own stderr-log, all web-apps in the host will write to the same output file.

...
<host id='foo.com'>
  <stderr-log path='/var/log/foo/stderr.log'
              rollover-period='1W'/>
  ...
</host>
...

access-log

Specify the access log file.

As a child of web-app, overrides the definition in the host that the web-app is deployed in. As a child of host, overrides the definition in the server that the host is in.

The default archive format is

path + ".%Y%m%d" or
  path + ".%Y%m%d.%H" if rollover-period < 1 day.

...
<host id=''>
  <access-log path='log/access.log'>
    <rollover-period>2W</rollover-period>
  </access-log>
  ...
</host>
...

The access log formatting variables follow the Apache variables:

The default format is:

"%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\""

resin:type allows for custom logging. Applications can extend a custom class from com.caucho.http.log.AccessLog. Bean-style initialization can be used to set bean parameters in the custom class.

...
<host id='foo.com'>
  <access-log resin:type='test.MyLog'>
             path='$server-root/foo/error.log'
             rollover-period='1W'>
    <init>
      <foo>bar</foo>
    </init>
  </access-log>
  ...
</host>
...

log

Configure the amount and destination of debug logging for the JDK java.util.logging.* API.

The default archive format is

path + ".%Y%m%d" or
  path + ".%Y%m%d.%H" if rollover-period < 1 day.

For example, to log everything to standard error use:

<resin>
  <log name='' level='all' path='stderr:' timestamp="[%H:%M:%S.%s]"/>
  ...
</resin>

A useful technique is to enable full debug logging to track down a problem:

<resin>
  ...
  <log name='' level='finer' path='log/debug.log'
       timestamp="[%H:%M:%S.%s]"
       rollover-period='1h' rollover-count='1'/>
  ...
</resin>

More examples of debug logging are in the Troubleshooting section.

The class that corresponds to <log> is com.caucho.log.LogConfig.

Log names

The JDK logging api uses a hierarchical naming scheme. Typically the name is aligned with a java class name. When you specify a name, all logging requests that use a name that starts with the name you have specified are matched. For example: <log name="example.hogwarts" ...> matches a logging request for both "example.hogwarts.System" and "example.hogwarts.gryffindor.System"

Resin's logging is based on Resin's source class names. The following are useful logs.

Use logging in applications

You can take advantage of the JDK's logging facility to add logging to your application. It's a good idea to keep such log messages in your code, when your application goes into production you can set the log level to warn; if problem's occur you can set it to finest and still have all of the information you need to troubleshoot.

import java.util.logging.Logger;
import java.util.logging.Level;

public class Foo {
  static protected final Logger log = 
    Logger.getLogger(Foo.class.getName());

  ...
  void doFoo(String bar)
  {
    // check for log level if your logging call does anything more
    // than pass parameters
    if (log.isLoggable(Level.FINER))
        log.entering("Foo","doFoo()", new Object[] { bar });
    ...

    log.info(...);

    try {
        ...
    } catch (ExpectedException ex) {
      log.log(Level.FINE, "expected exception", ex);
    }
  }
  ...
}

Log levels

The level for log tags matches the levels in the JDK java.util.logging.Level.

<logger> specifies multiple names for one destination

<log> can contain multiple <logger> entries.

<resin>
  <!-- log request and response info -->
  <log path='stdout:' timestamp='[%H:%M:%S.%s] '>
    <logger name="com.caucho.server.port.TcpConnection" level="fine"/>
    <logger name="com.caucho.server.http.HttpRequest" level="fine"/>
    <logger name="com.caucho.server.connection.AbstractHttpResponse" level="fine"/>
  </log>

  ...
</resin>

Log format string

The format for log tags is used to specify a format string for each log message. format recognizes EL-expressions. The EL variable log is a com.caucho.log.ELFormatter.ELFormatterLogRecord object.

<log name='' level='all' path='stderr:' timestamp="[%H:%M:%S.%s]"
     format=" ${'${'}log.level} ${'${'}log.loggerName} ${'${'}log.message}"/>

You can also use the Environment EL variables in your format string:

<host ...>

  <web-app>
    <log name='' level='all' path='log/debug.log' timestamp="[%H:%M:%S.%s]"
         format=" [] ${'${'}log.message}"/>

    ...
  </web-app>

  ...

</host>

[14:55:10.189] [/foo] `null' returning JNDI java:
       model for EnvironmentClassLoader[web-app:http://localhost:8080/foo]
[14:55:10.189] [/foo] JNDI lookup `java:comp/env/caucho/auth'
       exception javax.naming.NameNotFoundException: java:comp/env/caucho/auth
[14:55:10.199] [/foo] Application[http://localhost:8080/foo] starting

The fmt.sprintf() function can space pad the values and make the results look a little nicer:

<log name='' level='all' path='stderr:' timestamp="[%H:%M:%S.%s]"
     format=" ${'${'}fmt.sprintf('%-7s %45s %s',log.level,log.loggerName,log.message)}"/>

[14:28:08.137] INFO com.caucho.vfs.QJniServerSocket Loaded Socket JNI library.
[14:28:08.137] INFO com.caucho.server.port.Port http listening to *:8080
[14:28:08.137] INFO com.caucho.server.resin.ServletServer ServletServer[] starting
[14:28:08.307] INFO com.caucho.server.port.Port hmux listening to localhost:6802
[14:28:08.437] INFO com.caucho.server.host.Host Host[] starting 

fmt.sprintf() and fmt.timestamp() can be used to produce CSV files:

<log name='' level='all' path='log/debug.csv' timestamp=""
     format="${'${'}fmt.sprintf('%vs,%d,%d,%vs,%vs',fmt.timestamp('%Y-%m-%d %H:%M:%S.%s'), 
               log.threadID, log.level.intLevel(), log.loggerName, log.message)}"/>

"2003-11-17 14:46:14.529",10,800,"com.caucho.vfs.QJniServerSocket",
            "Loaded Socket JNI library."
"2003-11-17 14:46:14.549",10,800,"com.caucho.server.port.Port",
            "http listening to *:8080"
"2003-11-17 14:46:14.549",10,800,"com.caucho.server.resin.ServletServer",
            "ServletServer[] starting"
"2003-11-17 14:46:14.719",10,800,"com.caucho.server.port.Port",
            "hmux listening to localhost:6802"
"2003-11-17 14:46:14.850",10,800,"com.caucho.server.host.Host",
            "Host[] starting"
"2003-11-17 14:46:15.100",10,800,"com.caucho.server.webapp.Application",
            "Application[http://localhost:8080/freelistbm] starting"

com.caucho.log.SyslogHandler

On Unix systems, the SyslogHandler lets you log messages to syslog.

<log name="" level="warning">
  <handler resin:type="com.caucho.log.SyslogHandler">
    <facility>daemon</facility>
    <severity>notice</severity>
  </handler>
</log>

The possible values for facility are user, mail, daemon, auth, lpr, news, uucp, cron, authpriv, ftp, local0, local1, local2, local3, local4, local5, local6, local7. The default is daemon.

The possible values for severity are emerg, alert, crit, err, warning, notice, info, debug. The default is info.

See also `man 3 syslog' and `man syslog.conf'.

Log Paths

path is used to configure a destination for the messages. Typically, access-log, stdout-log, and stderr-log are configured to go to files, and log is configured to go to a file or to stderr or stdout so that they show up on the console screen.

  <log name="" level="all" path="stdout:"/>

You can use the Environment EL variables as part of your filesystem path:

  <log name="" level="all" 
       path="log/debug-${'${'}server.id}.log"
       rollover-period="1h" rollover-count="1"/>

Rollovers

Log rollovers are a way to stop your log files from getting too large. When a rollover is triggered, the existing log file is renamed and a new file is started.

Size based rollover

A size based rollover is triggered when the size of the file reaches a certain amount. The default Resin behaviour for log's is to rollover when the file size reaches 1mb.

rollover-size is used to specify the maximum size, and can be in bytes (50000), kilobytes (128kb), or megabytes (10mb). A value of -1 disables size based rollovers.

Time based rollover

A time based rollover is triggered when a certain period of time has passed since the last rollover. The default Resin behaviour is to perform no time based rollover, unless rollover-size has been disabled with a value of -1 in which case the default time period is 1 month.

rollover-period is used to specify the time period, and can be in days (15D), weeks (2W), months (1M), or hours (1h).

Archive files

When a rollover is triggered, the log file is renamed (archived) and a new log file is started.

archive-format is used to specify the name of the archive file. It can contain regular characters, EL Environment variables, and % codes that capture the current date and time. The % codes are the same as the ones used for timestamp (see Timestamp format string).

The default behaviour depends on the value of rollover-period. If rollover-period is greater than one day, or is not being used because rollover-size has been specified, the archive filename is the original path with .%Y%m%d appended. If rollover-period is less than one day, the archive filename is the original path with .%Y%m%d.%H appended.

Disabling rollovers

To completely disable rollovers, set the rollover-size to such a high number that it will never occur:

  <stdout-log path="log//stdout.log" rollover-size="1024mb"/>

Compression

Rollover log files can be compressed with gzip or zip. The extension of the archive-format determines the compression.

<log name="" level="warning" path='log/error.log'
     archive-format="%Y-%m-%d.error.log.gz"
     rollover-period="1D"/>

<access-log path="log/access.log"
            archive-format="access-%Y%m%d.log.gz"
            rollover-period="1D"/>

Timestamp format string

The timestamp for log tags is a format string which can contain percent codes which are substituted with time and date values.

    <log name='' level='all' path='stderr:' timestamp="[%H:%M:%S.%s]"/>

[22:50:11.648] Application[/doc] starting
[22:50:11.698] http listening to *:8080
[22:50:11.828] hmux listening to *:6802