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Overview

This article is part of a series:

Uptime Infrastructure Monitor provides many built in service monitors that allow you to monitor and alert on a wide array of services and applications within your enterprise. However, the standard Uptime Infrastructure Monitor service monitors may not be adequate to monitor all of the systems, applications and proprietary devices in your environment. In some cases, you may want to capture metrics that are unique to your environment. To do this, you can define custom service monitors to monitor custom services and applications to provide the level of in depth performance monitoring that you require. Using custom service monitors, you can monitor and graph historical performance data from just about any device in your environment.

This article series will focus on taking a simple command line script and incorporating it into Uptime Infrastructure Monitor. It will then demonstrate how to expand that script for use within a Custom with Retained Data service monitor that will enable you to not only register service outages in the event of a failure but also graph the historical performance trends. The final article in this series will guide you through the steps to further expand your custom service monitor so that it can be directly plugged in to the Uptime Infrastructure Monitor interface for use by your end users.

How Custom Service Monitors Work

In Uptime Infrastructure Monitor, you can configure custom service monitors to run any application or script. The application or script can then take an action, including launching commands on one of your agent systems using a built-in agent authentication protocol. Or, your script can use a different transport method to contact other servers and applications, or simple run commands on the monitoring station itself. The only limitation is that the application or script must return status information that Uptime Infrastructure Monitor will then use to determine the custom service monitor status.

The built-in agent authentication protocol provides a quick and easy way for you to have the Uptime Infrastructure Monitor agent run commands (or any application) on your agent-side system without the fear of unknown users being able to execute the same commands. The output from the agent-side commands will be returned to the monitoring station custom script for parsing. This enables you to create a script that can monitor many different agent systems without duplicating the script many times. The following diagram illustrates the custom service monitor process:

Step 1 - Creating the Agent Side Script

When designing a custom service monitor, you should consider what information that you want the monitor to collect. For example:

  • If you want to monitor the status of an application, you should first create a command line script or utility (or using an existing one) that returns the general status of a service that is on the agent system. 
  • If you want to gather performance metrics, ensure that the script to return a series of performance indicators to the console, otherwise simple output a message that can later be used to validate the status of the service or application. 

Once you have written your agent-side script, you will need to configure your Uptime Infrastructure Monitor agent to execute it. As a minimum, you must configure the following settings for each agent-side command:

  • For agents running on non-Windows systems, define a password and command pair in the agent-side password file.
  • For agents running on Windows, set a password via the Agent Console.
  • Verify that the agent-side command permissions allow the execution of the command by the user that the agent is run as. If the commands within your script require additional system permissions, you may have to alter the security settings for the execution of the agent.

For the purpose of this example, lets assume that we have designed an agent side script that returns information about the temperature and humidity levels around a given agent system. If we were to run this agent side script from the command line it would be executed as follows:

Note

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These example commands are formatted for non-Windows systems. The command format is very similar on Windows systems, but require minor syntax and path changes.

To define your password and command pair on a non-Windows agent system, do the following:

  1. Ensure that a file named .uptmpasswd is created in the Uptime Infrastructure Monitor agent bin directory -- either /opt/SPYNuptm/bin/ or /opt/uptime-agent/bin, depending the version of your agent. This file must be owned and readable by the user that the agent is run as (ex. uptimeagent or uptime users).
  2. Open the file .uptmpasswd in a text editor.
  3. Enter a password and command pair for each command that you want to run on the agent system. The following is the example format and an example of a agent-side commands:

    Format: [password] [command path, no arguments]

    Example file contents:

Windows agents do not require a password file. However, you must enter the equivalent settings into the Agent Console with the following steps:

  1. Launch the Agent Console on the system where the script will run. By default this is located in the Start Menu under “All Programs -> Uptime agent -> Uptime Agent Console.”
  2. The first step after launching the Agent console is to set a password in the ‘Agent Options’ section and click save. This password will be used to authenticate with the agent before running the script.
  3. After setting the password, tell the agent where the custom script is located on the server by clicking on the ‘Advanced’ option in the dropdown list and selecting ‘Custom Scripts.’
  4. On the Custom Scripts screen, you should see an example similar to:
    • Custom Command: dir
    • Path to Script: cmd.exe /c "dir c:"
  5. To continue this show-temp example, set the parameters to something similar to:
    • Custom Command: temp
    • Path to Script: cmd.exe /c “C:scriptsshow_temp.pl” (note: make sure to click Add/Edit before closing the window, otherwise your command will not be saved).
  6. If you haven’t done so yet, click Save, and Yes when asked to restart the agent. This will ensure that your new settings take effect.

The following is a sample configuration. Note the additional folder named rexec_commands , which contains a key/value pair of the command key.

Note

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If any changes are made to the Windows agent registry please restart the "up.time agent" service to see these changes take effect.

Step 2 - Creating the Monitoring Station Script

The next step is to write the monitoring station script that will attempt to execute your agent side script, validate the output, and then return status or performance information to Uptime Infrastructure Monitor.

The monitoring station script can be written in any language and format, provided that it adheres to these general rules:

  1. The script must return at least one line of output to the system console. Uptime Infrastructure Monitor will use this output to determine the status of the custom service monitor.
  2. The script must exit with a success status, unless there has been a problem during the execution of the script or you want to force a status for the service monitor. Acceptable return codes are:
    • exit 0 - The script executed without any errors, all output produced from the script will be parsed by Uptime Infrastructure Monitor to determine the service monitor status.
    • exit 1 - The service monitor status will be set to WNG (warning) and an outage will be recorded. The console output from the script will be placed in the custom service monitor status message.
    • exit 2 - The service monitor status will be set to CRIT (critical) and an outage will be recorded. The console output from the script will be placed in the custom service monitor status message.
  3. The script must accept the host name of the agent system as the first argument. Uptime Infrastructure Monitor will automatically add this argument to the arguments that are passed to the script.

In most cases, the monitoring station script will contact an agent system and attempt to run a predefined agent-side script like the one that was defined in step 1 above. You can use any transport tool -- such as rexec, rsh, or ssh -- to contact the agent system.

However, IDERA recommends using the bundled agentcmd utility the netcat utility to contact your agent systems from your monitoring station script:

  • To get started with custom scripts, or for implementations with only a handful of custom monitor instances, use agentcmd. The agentcmd utility is commonly called in the format listed below to execute a command on the agent side system. Please note that this utility is a helper tool, if you are using many custom monitor instances we recommend using an alternate tool.
    This example uses the settings that were configured above to execute the agent side script:

    Format:

    Example:

    For more information, click on Using the agentcmd Utility.

  • If you plan on implementing a number of custom monitor instances, use netcat. netcat must be downloaded and installed on the monitoring station if it isn't already installed as part of your operating system. The netcat utility is commonly called in the format listed below to execute a command on the agent side system. This example uses the settings that were configured above to execute the agent side script:

    Format:

    Example:

Note

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The 'rexec' text below does not indicate use of the 'rexec' system utility; it is simply a key word used to indicate to the agent that you are attempting to run a predefined command.

You will normally use netcat or agentcmd in the monitoring station script to return the results of an agent-side script, validate the status of those results, and return the status to Uptime Infrastructure Monitor. The following is an example of a monitoring station script:

# now use the info above to contact our agent, store the output in a file for parsing

Note

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The syntax to use agentcmd is different than netcat. Review the following example.

When using agentcmd, the above netcat example would look like this:

Step 3 - Adding your Custom Service Monitor to Uptime Infrastructure Monitor

The next step is to add a custom service monitor to the Uptime Infrastructure Monitor Web interface using the same process that you would use to add a standard custom service monitor to Uptime Infrastructure Monitor. The Custom monitor option is found in the List Other Monitors section of the Add New Service Instance page.

The Custom service monitor template has the following monitor specific settings available: 

Option NameDescriptionExample
Script NameThe script name is the path to your monitoring station script, this is the script that Uptime Infrastructure Monitor will execute when running this service monitor. Be sure to use the complete path wherever possible and that the path is to a locally mounted volume. For Windows script paths you must use UNIX style directory separators (/ instead of \) and also place double quotes around the entire script name.

UNIX/Linux Example:
/usr/local/uptime/check_temp.sh

 

Windows Example:
"C:/my-scripts/check_temp.bat"

ArgumentsThese are the arguments that you would like Uptime Infrastructure Monitor to pass into your monitoring station script. No arguments are required but please be aware that Uptime Infrastructure Monitor will automatically include the selected hostname as the first argument to your script.temp 60 80
Output WarningThis is the warning threshold used against the output returned from your monitoring station script. This is a textual comparison. You must select both a comparison method and a search string to enable the warning level threshold.Output contains: "warning"
Output CriticalThis is the critical threshold used against the output returned from your monitoring station script. This is a textual comparison. You must select both a comparison method and a search string to enable the critical level threshold.Output contains: "critical"

Based on the settings used in the example monitoring station script, configure the monitor with the following setting:

  • Enter a name and description for the monitor.
  • Select a host from the dropdown menu. Be sure to select the same host that your agent side script is on
  • In the Script Name field, enter the path to the custom script on your monitoring station. On Windows systems be sure to use UNIX style / instead of \ and put quotation marks around your path. For example: "C:/my files/check_temp.bat"
  • In the Arguments field, enter the arguments for the script. Uptime Infrastructure Monitor adds the agent name as the first argument automatically so do not include it.
  • Select contains from the Warning dropdown and enter WARNING as the search text.
  • Select contains from the Critical drop down and enter CRITICAL as the search text.
  • Complete the remainder of the monitor template as you would for a normal service monitor.

Example monitor configuration

The image below illustrates a sample monitor configuration. This service monitor will indicate a WARN or CRIT whenever the monitoring station custom script returns WARNING or CRITICAL in its output.

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