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The Joy of Decoupling

If you’re working with Splunk, you need to be thinking about decoupling. We’re not talking about the end of a relationship. We’re not alluding to a recent Hindi-language TV show, or a not-so-recent British TV show, or the American remake of that British TV show.

We’re talking about a quick, relatively easy maintenance task a Splunk administrator can perform that helps keep your system running at peak efficiency, prevents degraded performance, and saves money in the long run. The bigger the system, the more pressing the need for decoupling by using macros—and the deeper the problems that result from not having them.

Here are the basics:

It's common for Splunk users to write a query that interrogates a named data source. A query like 


functions the way it’s meant to, as long as the data you’re searching for remains at the designated location. (In this example, that location is the data source foo_0, and the query is coupled with that data source.) Splunk data is assigned the location, or indexed, according to rules based on how long the data will be kept, how much data is coming through, and the rate of data flow.

To query data at a particular location, a user needs to be up to date on where the data resides. When it works as it should, users get the information they need from the queries, reports, and alerts they initiate.

The problem comes when the data moves, which isn’t uncommon with Splunk systems. Splunk admins typically decide where to store data, and they change indexing protocols to preserve or improve system performance and stability. If the Splunk admin changes the data source from foo_0 to foo_1, for example, but our Splunk user never finds that out, problems result.

Smart Splunk users may find workarounds. A wildcard function (such as index=foo_*) can pull data from foo_0, foo_1, foo_2, and all other foo_ indexes. But if the data source moves entirely to a different, unrelated source, searches will come back without result.

Instead, a Splunk admin can set up a macro (say foo_idx) for users to employ instead. Users can use the same foo_idx macro forever, never worrying about where the required data resides. Instead, the Splunk admin points the macro to the correct index, changing that pointer when the location changes. The Splunk administrator establishes indexing rules as needed, understands the data flows, and works in the background to keep the macro up to date. Users can employ the same macro to support their business goals without keeping track of data-source changes. The macro acts as a buffer, effectively decoupling the search function from the data source.

The benefit of macros is relative to the size of your operation. At 100GB of data and more than five or six users per admin, it’s likely macros will preserve your system, saving you money and preventing mission failure in the long run. One client we recently helped runs about 240,000 searches an hour. Tracking down the searches that use the indexes in question and fixing them—without breaking anything in the process—was delicate, painstaking work.

In that case, a half-hour investment in writing a macro years ago could have saved weeks of clean-up time and prevented significant risk to the system. That’s part of the beauty of a macro: it prevents index mismatches before they occur.

The other wonderful thing about macros is that users don’t need to bother with them. Typical users who derive value from Splunk aren’t Splunk experts. They likely don’t write their own Splunk searches or even know Splunk search language. They benefit from data aggregation and visualization, but they aren’t paying attention to the details of data flow. And that’s a good thing, since they’re working in their own areas like plans, budgets, and staffing. Macros maintain their access to the data and insights and let administrators worry about the details.

If you’re using a large amount of data and aren’t sure you’re using macros, check them out. A little effort by an admin now can save a huge headache later. If your system shows a “parsing search” screen for more than three minutes, it’s too slow. That may be a warning, too.

Decoupling in your personal life? Can’t give you any advice on that. Decoupling your data with macros? Always a smart move. Got questions? Give us a call!