Customizing the Liberty environment

You can customize the Liberty environment by using certain specific variables to support the placement of product binary files and shared resources in read-only file systems.

About this task

The Liberty specific environment variables in the following list can be configured in the server.env file to customize the Liberty environment. The ${wlp.install.dir} configuration variable has an inferred location that is always set to the parent of the directory that contains the launch script.

  • WLP_USER_DIR

    This environment variable can be used to specify an alternative location for ${wlp.user.dir}. This variable must be an absolute path. If this variable is specified, the runtime environment looks for shared resources and server definitions in the specified directory. The ${server.config.dir} is equivalent to ${wlp.user.dir}/servers/serverName. If this environment variable is not specified, ${wlp.user.dir} is set to ${wlp.install.dir}/usr.

  • WLP_OUTPUT_DIR

    This environment variable can be used to specify an alternative location for server generated output such as logs, the workarea directory, and generated files. Files in the logs directory can include console.log, messages.log, and any generated FFDC files. Generated files can include server dumps that are created with the server dump or server javadump command. This variable must be an absolute path. If this environment variable is specified, ${server.output.dir} is set to the equivalent of WLP_OUTPUT_DIR/serverName. If this environment variable is not specified, ${server.output.dir} is the same as ${server.config.dir}.

    When the server command is used, the server process uses the output directory as its current working directory.

  • WLP_DEBUG_ADDRESS

    This environment variable can be used to specify an alternative port when you run the server in debug mode. The default value is 7777. When Liberty is run in debug mode from the server command, the following values are set JAVA_DEBUG="-Dwas.debug.mode=true -Dcom.ibm.websphere.ras.inject.at.transform=true -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=${WLP_DEBUG_ADDRESS}". If however, you run Liberty from the ws-server.jar executable JAR file, or the embedded Liberty server SPI, then you must use the same settings to enable debug mode for Liberty.

  • For AIX platformsLIBPATH

    This environment variable can be used to specify the setting for the path to the libraries in the Liberty server.env file.

You can specify WLP_OUTPUT_DIR, WLP_USER_DIR, and WLP_DEBUG_ADDRESS environment variables in server.env files. You can also specify JVM options in jvm.options files. Both server.env and jvm.options files work only when you use the server management script. If you use the ws-server.jar executable JAR file to launch your server, these files are not supported.

Procedure

  • Specify environment variables by using server.env files.
    You can use server.env files at the installation and server levels to specify environment variables such as JAVA_HOME, WLP_USER_DIR, and WLP_OUTPUT_DIR. For example:
    # Use a specific Java binary
    JAVA_HOME=/opt/ibm/java-i386-60/jre
    # JAVA_HOME=c:\Java
    Note:
    • The server.env files support only key=value pairs.
    • Empty lines and lines that start with the number sign (#) are ignored.
    • All characters are literal except for the caret (^) in Windows when the caret is used to escape a variable expansion character like the exclamation point (!).
    • There should be no white space surrounding the equal sign (=).
    • Shell and variable expansion are not supported.
    • WLP_USER_DIR can be specified only in the ${wlp.install.dir}/etc/server.env file because the purpose of this variable is to specify where the remaining configuration is located. After the remaining configuration is found and merged, no further configuration in a different location is expected, or supported.

    The server management script searches for server.env files in two locations: ${wlp.install.dir}/etc/server.env and ${server.config.dir}/server.env. If both files are present, the contents of the two files are merged; values in the server-level file take precedence over values in the runtime-level file.

    You can also specify these environment variables in the shell environment, but the server.env files take precedence over those variables.

  • Customize JVM options by using jvm.options files.
    You can use jvm.options files at the runtime and server levels to specify more server startup options, for example, -X arguments. The options are applied when the start, run, and debug actions are started through the server management script. Be sure to specify only one option per line. For example:
    # Set the maximum heap size to 1024m.
    -Xmx1024m
    
    # Set a system property.
    -Dcom.ibm.example.system.property=ExampleValue
    
    # Enable verbose output for class loading.
    -verbose:class
    
    # Enable verbose garbage collection.
    -verbose:gc
    
    # Specify an alternate verbose garbage collection log on IBM Java Virtual Machines only.
    -Xverbosegclog:verbosegc.log
    
    # Specify additional verbose garbage collection options on HotSpot Java Virtual Machines only.
    -Xloggc:verbosegc.log
    -XX:+PrintGCDetails
    -XX:+PrintGCTimeStamps
    -XX:+PrintHeapAtGC
    You can create multiple jvm.options files in the following locations:
    • ${wlp.install.dir}/usr/shared/jvm.options
    • ${server.config.dir}/configDropins/defaults/jvm.options
    • ${server.config.dir}/jvm.options
    • ${server.config.dir}/configDropins/overrides/jvm.options
    These files are merged in order from top to bottom before server start and are used as the JVM options for the server. If none of these files are present, then ${wlp.install.dir}/etc/jvm.options is read.
    Note:
    • Do not put property values in quotation marks.
    • Empty lines and lines that start with the number sign (#) are ignored.
    • All characters are literal except for the caret (^) in Windows when the caret is used to escape a variable expansion character like the exclamation point (!).
    • There should be no white space surrounding the equal sign (=).
    • Shell and variable expansion are not supported.

What to do next

If you start the Liberty server by using the server script, all of the operating system environment variables from the current session are available. If you start the server by using either the MBean or the Admin Center, the only available environment variables are those variables that are available to a remote command that is running on that system.