Search Manual

Write a custom search command

A custom search command is an executable file that reads data in and writes data out. This could be a Python script, a C++ program, or some other executable binary file. For simplicity, the file is referred to as the executable in this documentation.

Search command executable requirements

The search command executable should be located in the appropriate directory and given a name that follows some basic rules.

Executable location

The search command executable must be located in the appropriate $SPLUNK_HOME/etc/apps/<app_name>/bin/ directory. Most of the executables that ship with Splunk Enterprise are associated with the Search & Reporting app and are stored in $SPLUNK_HOME/etc/apps/search/bin. Refer to executables in that directory for examples.

If you use Splunk Cloud and want to create custom search commands, you must file a Support ticket. You do not have filesystem access to your Splunk Cloud deployment.

Executable name

The executable name should be the same as the command name that you will invoke in your Splunk search and follow the naming convention <command_name>.py. Search command names can consist of only alphanumeric (a-z and 0-9) characters. New commands should have unique names. The name cannot be the same name of any of the built-in or existing custom commands.

Build the command executable using the Splunk SDK for Python

With the Version 2 protocol, you can use platform-specific versions of external search executables. See Select a location for your custom search command.

For information about handling inputs, outputs, and errors with the Splunk SDK for Python, see Introduction to custom search commands on the Splunk dev portal.

After you build the search command executable, you must Add the custom command to your Splunk deployment.

Build the command executable using the Intersplunk.py file

As part of building the executable, you need to specify how to handle inputs, send output, and handle errors.

Handling inputs

With the Intersplunk.py file, the input to the executable should be formatted in pure CSV or in Intersplunk, which is a header section followed by a blank line followed by pure CSV body.

The simplest way to interpret your executable input is to use splunk.Intersplunk.readResults, which takes three optional parameters and returns a list of dicts (which represents the list of input events). The optional parameters are input_buf, settings, and has_header.

inputbuf

The inputbuf parameter where to read input from. If the parameter is None, which is the default value, the input is read from sys.stdin.

settings

The settings parameter is expected to be a dict where any information found in the input header is stored. The default value for this parameter is None, which means that no settings are recorded

has_header

The has_header parameter specifics whether or not input header is used. The default value for this parameter is True.

To indicate if your executable expects a header, use the enableheader attribute. The default value for the enableheader attribute is True, which means that the input will contain the header section and you are using the Intersplunk format.

If your executable does not expect a header section in the input, enableheader is False, you can directly use the Python CSV module to read the input. For example:

import csv

r = csv.reader(sys.stdin)
for l in r:
...

The advantage of using the Python CSV is that you can break at any time in the for loop, and only lines in the input that you had iterated to at that point are read into memory. This leads to much better performance in some use cases.

Sending output

You can also use the Intersplunk.py file to construct your output of the executable. splunk.Intersplunk.generateErrorResults takes a string and writes the correct error output to sys.stdout. splunk.Intersplunk.outputResults takes a list of dict objects and writes the appropriate CSV output to sys.stdout.

To output data, add:

splunk.Intersplunk.outputResults(results)

The output of your executable is expected to be pure CSV. For an error condition, simply return a CSV with a single "ERROR" column and a single row (besides the header row) with the contents of the message.

Handling errors

The arguments that are passed to your executable (in sys.argv) are the same arguments that are used to invoke your custom command in the search language, unless your executable has the attribute supports_getinfo = true. The supports_getinfo attribute indicates that the first argument to your executable is either __GETINFO__ or __EXECUTE__. This allows you to call the executable with the command arguments at parse time to check for syntax errors before any execution of the search. Errors at this time will short circuit any real execution of the search query. If called with __GETINFO__, this also allows you to dynamically specify the properties of your executable (such as streaming or not) depending on your arguments.

If your executable has the attribute supports_getinfo set to 'true', you should first make a call like:

(isgetinfo, sys.argv) = splunk.Intersplunk.isGetInfo(sys.argv)

This call will strip the first argument from sys.argv and check if you are in GETINFO mode or EXECUTE mode. If you are in GETINFO mode, your executable should use splunk.Intersplunk.outputInfo() to return the properties of your executable or splunk.Intersplunk.parseError() if the arguments are invalid.

The definition of outputInfo() and its arguments is as follows:

def outputInfo(streaming, generating, retevs, reqsop, preop, timeorder=False)

You can also set these attributes in the commands.conf file. See How to edit a configuration file.

See also

• To decide where to implement your command, see Select a location for your custom search command.
• To learn about the supported protocols and SDKs, see About writing custom search commands.
• To learn about security best practices with custom search commands, see Security responsibilities with custom commands.
• For information about the custom search command parameters, see commands.conf.