BSF Detector

The BSFDetector lets you run arbitrary scripts using the Bean Scripting Framework (BSF) to determine if a service exists. This can be a script written in any of the languages BSF supports. The only requirement is that the script returns the string OK if it passes.

The BSFDetector passes the map, ip_addr, svc_name, and results variables as beans to the script.

Detector facts

Implementation

org.opennms.netmgt.provision.detector.bsf.BSFDetector

Configuration and use

Table 1. Optional parameters for the BSFDetector
Parameter	Description	Default value
fileName	Path to the file on the OpenNMS server that contains the BSF-compatible script to run.	none
langClass	Short name of the language the script is written in. Choices: jython beanshell groovy	none
bsfEngine	BSF engine to use when running the script. Choices: `bsh.util.BeanShellBSFEngine` `org.codehaus.groovy.bsf.GroovyEngine` `org.apache.bsf.engines.jython.JythonEngine`	none
fileExtensions	Comma-separated list of file extensions. Include them to indicate the only file types that the BSF instance recognizes as containing valid scripts.	none
runType	Mode to run BSF script. Choices: eval: expects script to print `OK`/`NOK` status for validation. exec: expects script to manipulate provided results hashmap directly.	eval

Avoid non-character names for parameters to avoid problems in the script languages.

Timeout and Retry

The BSFDetector does not perform any timeout or retry processing on its own. If you require retry and/or timeout behavior, you must implement it in the script itself.

Requirements for the script (run-types)

Depending on the run-type, the script must provide its results in different ways. For minimal scripts with simple logic, a run-type of eval is the easiest option. Scripts running in eval mode must return a string matching a status code of OK or NOK.

A script with more than one line of logic requires a run-type of exec. Scripts running in exec mode do not need to return anything, but they have to add a status entry with a status code to the results object. Additionally, the results object can also carry a "reason":"message" entry that is used in non-OK states.

Commonly used language settings

The BSFDetector supports many languages. The following table provides the required setup for commonly used languages.

Table 2. BSF language options
Language	langClass parameter	bsfEngine parameter	Required library
BeanShell	beanshell	bsh.util.BeanShellBSFEngine	supported by default
Groovy	groovy	org.codehaus.groovy.bsf.GroovyEngine	groovy-all-[version].jar
Jython	jython	org.apache.bsf.engines.jython.JythonEngine	jython-[version].jar

If you are using a Groovy or Jython script, you need to place the required library file in the ${OPENNMS_HOME}/lib directory and restart the Meridian service.

Example configurations

BeanShell example

<detector name="MinimalBeanShell" class="org.opennms.netmgt.provision.detector.bsf.BSFDetector">
    <parameter key="bsfEngine" value="bsh.util.BeanShellBSFEngine"/>
    <parameter key="langClass" value="beanshell"/>
    <parameter key="fileName" value="/opt/opennms/etc/scripts/MinimalBeanShell.bsh"/>
    <parameter key="runType" value="eval"/>
</detector>

BeanShell example MinimalBeanShell.bsh script file

File testFile = new File("/tmp/TestFile");
if (testFile.exists()) {
  return "OK";
} else {
  results.put("reason", "file does not exist");
  return "NOK";
}

Groovy example

The Groovy language requires the installation of an additional library.

Groovy example for run-type of eval

<detector name="MinimalGroovy" class="org.opennms.netmgt.provision.detector.bsf.BSFDetector">
    <parameter key="bsfEngine" value="org.codehaus.groovy.bsf.GroovyEngine"/>
    <parameter key="langClass" value="groovy"/>
    <parameter key="fileName" value="/opt/opennms/etc/scripts/MinimalGroovy.groovy"/>
    <parameter key="runType" value="eval"/>
</detector>

Groovy example MinimalGroovy.groovy script file for run-type of eval

File testFile = new File("/tmp/TestFile");
if (testFile.exists()) {
  return "OK";
} else {
  results.put("reason", "file does not exist");
  return "NOK";
}

Groovy example for run-type of exec

<detector name="MinimalGroovy" class="org.opennms.netmgt.provision.detector.bsf.BSFDetector">
    <parameter key="bsfEngine" value="org.codehaus.groovy.bsf.GroovyEngine"/>
    <parameter key="langClass" value="groovy"/>
    <parameter key="fileName" value="/opt/opennms/etc/scripts/MinimalGroovy.groovy"/>
    <parameter key="runType" value="exec"/>
</detector>

Groovy example MinimalGroovy.groovy script file for run-type of exec

def testFile = new File("/tmp/TestFile");
if (testFile.exists()) {
  results.put("status", "OK")
} else {
  results.put("reason", "file does not exist");
  results.put("status", "NOK");
}

Jython example

The Jython (Java implementation of Python) language requires the installation of an additional library.

Jython example for run-type of exec

<detector name="MinimalJython" class="org.opennms.netmgt.provision.detector.bsf.BSFDetector">
    <parameter key="bsfEngine" value="org.apache.bsf.engines.jython.JythonEngine"/>
    <parameter key="langClass" value="jython"/>
    <parameter key="fileName" value="/opt/opennms/etc/scripts/MinimalJython.py"/>
    <parameter key="runType" value="exec"/>
</detector>

Jython example MinimalJython.py script file for run-type of exec

from java.io import File

if (File("/tmp/TestFile").exists()):
        results.put("status", "OK")
else:
        results.put("reason", "file does not exist")
        results.put("status", "NOK")

We have to use a run type of exec here because Jython chokes on the import keyword in eval mode.