Defining plug-in variables

You can define name and value pairs in config.json file to reuse as variables in several areas of the plug-in.

Name and value pairs are defined within a parms object.
  • An item that is defined in parms can be referenced by name in config.json.
  • Component and link transforms can access the values, and then put them in the topology document. Values in the topology document can then be used by other plug-in interfaces and role lifecycle scripts.
  • All names that are defined in a parms object must have a value.
  • A parms defined in config.json is not exposed in the console unless it is referenced config_meta.json. Plug-in developers have the option of modifying the value and rebuilding the plug-in if they want to customize settings for deployments in their environment.
  • If a parms is referenced in config_meta.json, the value can be modified in the console. This capability enables developers to set a value to "null" or set a default value and then provide a way for a user to modify the value.

    To change a value in the console, click Catalog > System Plug-ins. Select a plug-in and then click Configure in the toolbar.

For information about how config.json is used to define global plug-in information such as pattern type associations, parts, and node parts, see "Pattern type packaging reference."

Example

The wasoracle plug-in provides an example of parms reuse. A parms object in config.json defines two variables for the JDBC driver.
"WASOracle" : [
   {
      "parts" : [
         {
            "part"  : "parts/wasxoracle.scripts.tgz",
            "parms" : {
                 "jdbcDriver"     : "$JDBC_DRIVER",
                 "jdbcInstallDir" : "$JDBC_INSTALL_DIR"
            }
         }
      ]
   }
Later in the same file, the following parms object defines values for JDBC_DRIVER and JDBC_INSTALL_DIR
   "parms" : {
      "JDBC_DRIVER"      : null,
      "JDBC_INSTALL_DIR" : "/opt/oraclejdbcjar"
Because the JDBC_DRIVER value is null, the user must specify a JDBC file name before the plug-in can be enabled, and a warning icon is displayed next to the plug-in on the System Plug-ins page to indicate that the configuration of the plug-in is incomplete. The config_meta.json file for the wasoracle plug-in includes "id" : "parms.JDBC_DRIVER" to reference the JDBC_DRIVER name and value pair that is defined in config.json. 
[
  {
   "id"          : "parms.JDBC_DRIVER",
   "path"        : "files",
   "label"       : "ORA_JDBC_DRIVER",
   "description" : "ORA_JDBC_DRIVER_DESC",
   "type"        : "file",
   "extensions"  : [ "jar" ]
   }
]