BSFMonitor

This monitor runs a Bean Scripting Framework (BSF)-compatible script to determine the status of a service. Users can write scripts to perform highly customized service checks.

This monitor is not optimized for scale. It is intended for a small number of custom checks or prototyping of monitors.

BSFMonitor versus SystemExecuteMonitor

The BSFMonitor avoids the overhead of fork(2) that the SystemExecuteMonitor uses. The BSFMonitor also grants access to a selection of Meridian internal methods and classes that the script can use.

Monitor facts

Class Name

org.opennms.netmgt.poller.monitors.BSFMonitor

Configuration and use

Table 1. Monitor-specific parameters for the BSFMonitor
Parameter	Description	Default
Required
file-name	Path to the script file.	n/a
bsf-engine	The BSF Engine to run the script in different languages: bsh.util.BeanShellBSFEngine org.codehaus.groovy.bsf.GroovyEngine org.apache.bsf.engines.jython.JythonEngine	n/a
Optional
run-type	One of eval or exec	eval
lang-class	The BSF language class, like `groovy` or `beanshell`	filename extension is interpreted by default
file-extensions	Comma-separated list of extensions	n/a

This monitor implements the Common Configuration Parameters.

Table 2. Beans available for the script
Variable	Description	Type
map	The map contains all parameters passed to the monitor from the service definition in `poller-configuration.xml`.	Map<String, Object>
ip_addr	The IP address currently being polled.	String
node_id	The node ID of the node the `ip_addr` belongs to.	int
node_label	The node label of the node the `ip_addr` and service belong to.	String
svc_name	The name of the service being polled.	String
bsf_monitor	The instance of the BSFMonitor object calling the script. Useful for logging via its log(String sev, String fmt, Object... args) method.	BSFMonitor
results	The script is expected to put its results into this object. You should set the status indication into the entry with key `status`. If the status is not OK, a key `reason` should contain a description of the problem.	HashMap<String, String>
times	The script is expected to put one or more response times into this object.	LinkedHashMap<String, Number>

Additionally, every parameter added to the service definition in poller-configuration.xml is available as a string object in the script. The key attribute of the parameter represents the name of the string object and the value attribute represents the value of the string object.

Please keep in mind that these parameters are also accessible via the map bean.

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

Response codes

The script has to provide a status code that represents the status of the associated service. The following status codes are defined:

Table 3. Status codes
Code	Description
OK	Service is available.
UNK	Service status is unknown.
UNR	Service is unresponsive.
NOK	Service is unavailable.

Response time tracking

Examples use CentOS/RHEL path name. For Debian/Ubuntu, use /var/lib/opennms/rrd/response.

By default, the BSFMonitor tracks the duration of the script runtime as the response time. If the response time should be persisted, add the following parameters:

RRD response time tracking for this service in poller-configuration.xml

<!-- where in the filesystem response times are stored -->
<parameter key="rrd-repository" value="/opt/opennms/share/rrd/response" />

<!-- name of the rrd file -->
<parameter key="rrd-base-name" value="minimalbshbase" />

<!-- name of the data source in the rrd file -->
<!-- by default "response-time" is used as ds-name -->
<parameter key="ds-name" value="myResponseTime" />

It is also possible to return one or many response times directly from the script. To add custom response times or override the default one, add entries to the times object. The entries are keyed with a string that names the data source and have as values a number that represents the response time. To override the default response time data source, add an entry into times named response-time.

Timeout and retry

The BSFMonitor 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 has to provide its results in different ways. For minimal scripts with simple logic, a run-type of eval is the best option. Scripts running in eval mode have to return a string that matches one of the status codes.

If your script is more than a one-liner, a run-type of exec is required. Scripts running in exec mode need not 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 BSF supports many languages. The following table provides the required setup for commonly used languages.

Table 4. BSF language setups
Language	lang-class	bsf-engine	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`

BeanShell example

BeanShell example poller-configuration.xml

<service name="MinimalBeanShell" interval="300000" user-defined="true" status="on">
  <parameter key="file-name"  value="/tmp/MinimalBeanShell.bsh"/>
  <parameter key="bsf-engine" value="bsh.util.BeanShellBSFEngine"/>
</service>

<monitor service="MinimalBeanShell" class-name="org.opennms.netmgt.poller.monitors.BSFMonitor" />

BeanShell example MinimalBeanShell.bsh script file

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

Groovy example

The use of the Groovy language requires an additional library. Copy a compatible groovy-all.jar into the ${OPENNMS_HOME}/lib folder and restart Meridian to make Groovy available for the BSFMonitor.

Groovy example poller-configuration.xml with default run-type set to eval

<service name="MinimalGroovy" interval="300000" user-defined="true" status="on">
  <parameter key="file-name"  value="/tmp/MinimalGroovy.groovy"/>
  <parameter key="bsf-engine" value="org.codehaus.groovy.bsf.GroovyEngine"/>
</service>

<monitor service="MinimalGroovy" class-name="org.opennms.netmgt.poller.monitors.BSFMonitor" />

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

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

Groovy example poller-configuration.xml with run-type set to exec

<service name="MinimalGroovy" interval="300000" user-defined="true" status="on">
  <parameter key="file-name"  value="/tmp/MinimalGroovy.groovy"/>
  <parameter key="bsf-engine" value="org.codehaus.groovy.bsf.GroovyEngine"/>
  <parameter key="run-type" value="exec"/>
</service>

<monitor service="MinimalGroovy" class-name="org.opennms.netmgt.poller.monitors.BSFMonitor" />

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

bsf_monitor.log("ERROR", "Starting MinimalGroovy", null);
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 use of the Jython (Java implementation of Python) language requires an additional library. Copy a compatible jython-x.y.z.jar into the ${OPENNMS_HOME}/lib folder and restart Meridian to make Jython available for the BSFMonitor.

Jython example poller-configuration.xml with run-type exec

<service name="MinimalJython" interval="300000" user-defined="true" status="on">
  <parameter key="file-name"  value="/tmp/MinimalJython.py"/>
  <parameter key="bsf-engine" value="org.apache.bsf.engines.jython.JythonEngine"/>
  <parameter key="run-type" value="exec"/>
</service>

<monitor service="MinimalJython" class-name="org.opennms.netmgt.poller.monitors.BSFMonitor" />

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

from java.io import File

bsf_monitor.log("ERROR", "Starting MinimalJython.py", None);
if (File("/tmp/TestFile").exists()):
        results.put("status", "OK")
else:
        results.put("reason", "file does not exist")
        results.put("status", "NOK")

The use of a run-type of exec is required here because Jython chokes on the import keyword in eval mode.

As proof that this is really Python, notice the substitution of Python’s None value for Java’s null in the log call.

Advanced examples

The following example references all beans that are exposed to the script, including a custom parameter.

Groovy example poller-configuration.xml

Example uses CentOS/RHEL path names. For Debian/Ubuntu, use /var/lib/opennms/rrd/response.

<service name="MinimalGroovy" interval="30000" user-defined="true" status="on">
  <parameter key="file-name"  value="/tmp/MinimalGroovy.groovy"/>
  <parameter key="bsf-engine" value="org.codehaus.groovy.bsf.GroovyEngine"/>

  <!-- custom parameters (passed to the script) -->
  <parameter key="myParameter" value="Hello Groovy" />

  <!-- optional for response time tracking -->
  <parameter key="rrd-repository" value="/opt/opennms/share/rrd/response" />
  <parameter key="rrd-base-name" value="minimalgroovybase" />
  <parameter key="ds-name" value="minimalgroovyds" />
</service>

<monitor service="MinimalGroovy" class-name="org.opennms.netmgt.poller.monitors.BSFMonitor" />

Groovy example Bean referencing script file

bsf_monitor.log("ERROR", "Starting MinimalGroovy", null);

//list of all available objects from the BSFMonitor
Map<String, Object> map = map;
bsf_monitor.log("ERROR", "---- map ----", null);
bsf_monitor.log("ERROR", map.toString(), null);

String ip_addr = ip_addr;
bsf_monitor.log("ERROR", "---- ip_addr ----", null);
bsf_monitor.log("ERROR", ip_addr, null);

int node_id = node_id;
bsf_monitor.log("ERROR", "---- node_id ----", null);
bsf_monitor.log("ERROR", node_id.toString(), null);

String node_label = node_label;
bsf_monitor.log("ERROR", "---- node_label ----", null);
bsf_monitor.log("ERROR", node_label, null);

String svc_name = svc_name;
bsf_monitor.log("ERROR", "---- svc_name ----", null);
bsf_monitor.log("ERROR", svc_name, null);

org.opennms.netmgt.poller.monitors.BSFMonitor bsf_monitor = bsf_monitor;
bsf_monitor.log("ERROR", "---- bsf_monitor ----", null);
bsf_monitor.log("ERROR", bsf_monitor.toString(), null);

HashMap<String, String> results = results;
bsf_monitor.log("ERROR", "---- results ----", null);
bsf_monitor.log("ERROR", results.toString(), null);

LinkedHashMap<String, Number> times = times;
bsf_monitor.log("ERROR", "---- times ----", null);
bsf_monitor.log("ERROR", times.toString(), null);

// reading a parameter from the service definition
String myParameter = myParameter;
bsf_monitor.log("ERROR", "---- myParameter ----", null);
bsf_monitor.log("ERROR", myParameter, null);

// minimal example
def testFile = new File("/tmp/TestFile");
if (testFile.exists()) {
  bsf_monitor.log("ERROR", "Done MinimalGroovy ---- OK ----", null);
  return "OK";
} else {

  results.put("reason", "file does not exist");
  bsf_monitor.log("ERROR", "Done MinimalGroovy ---- NOK ----", null);
  return "NOK";
}