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Getting started with Cribl LogStream

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Data Preview

Data Preview is a feature that allows for visual inspection of events as they make their trip into a Pipeline. It helps users shape and control events before they're delivered to a destination, as well as assisting with troubleshooting LogStream Functions.

Preview works by taking a set of Sample events, passing them through the Pipeline, and displaying the result in a separate pane. Any time a Function is modified, added, or removed, the Pipeline changes, and so does its output.

Preview options

While you're in a Pipeline, you can add samples through one of the supported options: Upload (Browse and attach), Paste, or Capture. The Upload and Paste options work with content that needs to be broken into events, while the Capture option works with events only.

Adding Sample Data (Using Paste as an Example)

When you click on the corresponding option, you'll be presented with a modal like the one shown below.

Add Sample Data modal


The Capture screen is slightly different – it does not require event breaking.

Paste Area

This is where the content of the paste (or uploaded file) is displayed.

Event Breaker Settings

An Event Breaker is a regular expression that tells Cribl LogStream how to break the file or pasted content into events. Breaking will occur at the start of the match. Cribl LogStream ships with several common breaker patterns out of the box, but you can also configure custom breakers. The UI here is interactive, and you can iterate until you find the exact pattern.


The Fields section enables users to add, or overwrite. key/value pairs on the sample.

In Tab: Displaying Samples on the Way IN to the Pipeline

There are two display options for the event: Event and Table. (You can also download data as JSON or NDJSON, using the Advanced Settings menu at the top right.) Each format can be useful, depending on the type of data you are previewing.

Event, Table, Advanced, and Download options

As you add more samples to your system, you can easily access them via the Samples drop-down near the top right, under Quick Stats.

Selecting an existing sample

Out Tab: Displaying Samples on the Way OUT of the Pipeline

As data traverses Functions in a Pipeline, events can be modified, and some might be dropped altogether. When they're dropped, the Out tab displays them as grayed-out text, with strikethrough. You can control their display using the Advanced Settings menu's Show Dropped Events slider.

When LogStream's processing adds new fields, these fields are highlighted green. You can control these fields' display using the Select Fields drop-down.

Dropped and added fields in a Pipeline's output

Updated 23 days ago

Data Preview

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