To set the start-up log level for the ESP server, use the loglevel parameter on the command line, as shown in the following example: 

This parameter sets the log level for each specified context before the server starts to perform its basic functions.

Using the SAS Logging Facility Configuration File

By default, the ESP server writes logging messages to the local terminal screen (standard output).  

The ESP server can use a SAS logging configuration file, specified using the logconfig parameter. The logconfig parameter accepts a logging configuration file that can enable additional logging features. The logging configuration file can configure the output to go to a rolling log file appender instead of the local terminal screen. Other SAS loggers can be configured for additional debugging information. An example logging configuration file, esp-logger, is shipped in the configuration directory.

The default location for configuration files is /opt/sas/viya/config/etc/SASEventStreamProcessingEngine/default under Linux and \SAS\Viya\SASEventStreamProcessingEngine\default under Windows. In Windows operating environments, if the PUBLIC environment variable is defined, it is placed at the beginning of the configuration directory path, before \SAS\.

The example logging configuration file esp-logger directs log messages to the local terminal. To use a rolling file appender instead, follow these steps:

1. Copy the esp-logger.xml file from the configuration directory to a file called my-esp-logger.xml.
2. Edit the my-esp-logger.xml file.
3. Use comment delimiters (<!-- -->) to comment out the ConsoleAppender:
   <!--
         Simple console appender
     -->
   <!--  
     <appender class="ConsoleAppender" name="consoleAppender">
       <param name="ImmediateFlush" value="true"/>
       <layout>
         <param name="ConversionPattern"
                value="%d; %-5p; %t; %c; (%F:%L); %m"/>
       </layout>
     </appender>
   -->
4. Remove the comments around the RollingFileAppender to enable it:
   <!--
         Simple rolling file appender, logfiles decorated by PID and DATE.
         New file for each DAY.
         Comment out when not using to prevent empty log files from being created
         NOTE: THERE ARE TWO FILE PATTERNS BELOW, choose the one that
               best fits your needs. Make sure only one is active and
               the other is commented out.
     -->
         <appender class="RollingFileAppender" name="timeBasedRollingFileAppender">
           <param name="Append" value="true"/>
           <param name="ImmediateFlush" value="true"/>
           <rollingPolicy class="TimeBasedRollingPolicy">
             <!-- Linux fileNamePattern -->
             <param name="fileNamePattern" value="/opt/sas/viya/config/var/log/SASEventStreamProcessingEngine/esp-%S{jobid}-%d{yyyy-MM-dd}.log" />
             <!-- Windows fileNamePattern -->
             <param name="fileNamePattern" value="%S{OSENV.PUBLIC}/SAS/Viya/SASEventStreamProcessingEngine/log/esp-%S{jobid}-%d{yyyy-MM-dd}.log" />
           </rollingPolicy>
           <layout>
              <param name="HeaderPattern"
                value="Host: '%S{hostname}', Process: '%S{pid}', OS: '%S{os_bits} %S{os_family}', OS Release: '%S{os_release}'"/>
              <param name="ConversionPattern"
                value="%d; %-5p; %t; %c; (%F:%L); %m"/>
           </layout>
        </appender>

5. Choose one of the fileNamePattern options, based on the operating system (Linux or Windows) that you are using. Comment out the fileNamePattern for the operating system that you are not using. The ESP server must have permission to write to the directory specified as the value of the fileNamePattern.  

6. At the bottom of the file, update the root logger to use the timeBasedRollingFileAppender:

   <!--
         Root logger
     -->
     <root>
       <level value="info"/>
       <!--
            comment out next line to prevent log from going to the screen
       -->
      <!--
       <appender-ref ref="consoleAppender"/>
     -->
       <!-- uncomment this block for rolling file logging to $DFESP_HOME/log/esp_PID_YYYYMMDD.log
       -->
            <appender-ref ref="timeBasedRollingFileAppender"/>
     </root>

7. Start the ESP server with the logconfig parameter:

   dfesp_xml_server -logconfig my-esp-logger.xml

8. After you start the ESP server, you can find the log file in the path specified with the fileNamePattern param.

Specifying ESP Server Logging Contexts When Using the logconfig Parameter 

You cannot specify the ESP server logging contexts, except for the esp logging context, in the logging configuration file specified using the logconfig parameter. You should specify the ESP server logging contexts using the -loglevel parameter. When you use both loglevel and logconfig parameters, the logging context values specified on the loglevel parameter are sent to the appender configured for the root logger.  

Note: The esp logging context is equivalent to the DF.ESP logger. The esp logger level specified using the loglevel parameter overrides the DF.ESP logger configured in the logging configuration file specified using the logconfig parameter.

For example, to configure the common.http logging context to trace and have the output sent to a rolling file appender, as configured above, start the ESP server using the following command: