Manage Your Event Stream, a Guide

Getting started with Sentry error monitoring is pretty straightforward — create a Sentry project, install and initialize the Sentry SDK in your code and you’re ready to go. Once completed, any Exception, Runtime Error or Crash that occurs wherever and whenever your code is running, will be aggregated in your Event Stream. Depending on your portfolio, your stream might be aggregating millions of events in no time. Sending all your errors to Sentry is generally a good practice. This ensures greater visibility into the health and performance of your application code. However, with just this basic setup in place, you might risk:

  1. Flooding your event stream with excessive noise such as errors from 3rd party libraries, errors from unstable versions of your code, etc.
  2. Getting spammed with alert notifications about things you don’t care about or worse — lose track of the critical issues that are hiding in your code.

Filtering this noise will help ensure that you only see the relevant errors that you want or need to fix. Also, if you’re on an event-quota based plan, unnecessary noise might end up draining your quota and leaving you blind when and where it matters.

To cope with these challenges, Sentry provides several mechanisms that allow you to control the type and amount of events that make it to your event stream.

1. Filtering

Filtering is the optimal way to manage your event stream and quota. It ensures that only actionable errors related to your source code make it to your event stream. If it’s redundant, filter it — clear your event stream from undesired “noise” and keep your alert notifications for the errors that matter.

Outbound Filters

Sentry SDK has several configuration options that can be used to filter unwanted errors from reaching your account. By default, all errors will be sent. Those include:

  • beforeSend: A callback method invoked before an event is sent from your code runtime to Sentry with the event object passed to it as a parameter. Developers can hook into this callback to modify the event or drop it (filter) completely by returning null. You can filter outgoing events based on custom logic and data available on the SDK and event object like tags, environment, release version, error attributes, etc.

For JavaScript SDKs:

  • whitelistUrls: Domains that might raise acceptable exceptions represented in a regex pattern format.
  • blacklistUrls: A list of strings or regex patterns that match error URLs which should be blocked from sending events.

    Note: Configuring both options on the SDK can be used to blacklist subdomains of the domains listed in whitelistUrls.

  • ignoreErrors: Instruct the SDK to never send an error to Sentry if it matches any of the listed error messages. If no message is available, the SDK will try to compare against an underlying exception type and value.

For more information and code samples checkout:

Inbound Data Filters

While using outbound filters requires changes to your source code and applying them depend on your next deployment, Inbound Filters (or server-side filters) can be easily configured in your Sentry account under [Project Settings] > Inbound Filters > Data Filters.

These include predefined configurations to filter out:

  • Common browser extension errors
  • Events coming from localhost
  • Known legacy browsers errors
  • Errors caused by known web crawlers crawling your site

Built-in Inbound Filters

Those also include custom filters to filter out errors:

  • By their error message
  • From specific release versions of your code
  • From certain IP addresses

Custom Inbound Filters

Once applied, you can track the number of filtered errors using the graph provided at the top of the Inbound Data Filters view.

Built-in Inbound Filters

For more information on inbound filtering options take a look at:

2. Event Grouping

Any event that makes it from your source code runtime though the outbound and inbound filters will be persisted and available in your Event Stream. Similar Events are grouped into unique Issues based on the event’s Fingerprint. An event’s fingerprint (and proper grouping) relies on its stack trace. If a stack trace is not available, the fingerprint will be determined by the type and value of the Exception associated with this event. If all else fails, the fingerprint will default to the Event Message.

Sentry provides various configuration options to modify and fine-tune event grouping. For more information, take a look at our docs on Grouping & Fingerprints.

Optimize your Event Grouping

Proper grouping of events into issues is essential for maintaining a meaningful Issue Stream, gaining accurate visibility into the health of your application code, and leveraging Sentry workflows and integrations in a meaningful way. To make sure your events are grouped properly:

  1. With JavaScript SDKs, a minimized source code will result in a nondeterministic stack trace that will mess up associated event grouping. Make sure Sentry has access to your Source Maps and minimized artifacts. For more information, take a look at our documentation on Uploading Source Maps.

JavaScript stack trace without source maps JavaScript stack trace with source maps

  1. For native errors, debug information files (also known as symbols) should be uploaded so Sentry can extract stack traces and symbolicate stack frames into function names and line numbers. For more information, take a look at the following resources:

3. Applying Workflows

Now that your event stream is fine-tuned to reflect real problems in your code, it’s an excellent practice to react to errors as they happen. If an issue reflects a real problem in your code, resolve it; otherwise— discard.

Resolve Issue

You’ve been alerted on a new error in your code? Jump into the issue page to see all the data you need to know about the issue. If it’s a real error in your code, assign a team member to resolve it. Don’t forget to let Sentry know once it’s resolved.

For more information take a look at The Sentry Workflow — Resolve

Delete & Discard

If there is an irrelevant reoccurring issue that you are unable or unwilling to resolve, you can delete and discard it from the issue details page by clicking Delete and discard future events. This will remove the issue and event data from Sentry and filter out matching events before they reach your stream.

Delete and Discard

Discarded issues are listed under [Project Settings] > Inbound Filters > Discarded Issues and can always be un-discarded to allow future events back in your stream.

List of Discarded Issues

Note: Once you’ve identified a set of discarded issues, it might make sense to go back to your SDK configuration and add the related errors into your before-send client-side filtering.

4. Rate Limiting

Rate limiting allows you to limit the amount of events Sentry accepts per-project for a defined period — minutes, hours, a day. While this is quite useful for managing your monthly event quota, keep in mind that once a defined threshold is crossed, subsequent events will be dropped. Therefore, your rate limit shouldn’t be constantly hit, but rather defined as a ceiling intended to protect you from unexpected spikes that might drain your monthly quota and leave you in the dark for a while.

Under [Project Settings] » Client Keys » Configure, you can create multiple keys per-project and assign different (or no) limits to each key. This will allow you to dynamically allocate keys (with varying thresholds) depending on Release, Environment, etc.

Per DSN Key rate limits

For more information: Rate Limiting Projects

Spike Protection

Sentry also applies a dynamic rate limit to your account designed to protect you from short-term spikes. However, we would recommend applying all of the previously mentioned methods. For more information:

Workflows for Managing your Event Stream

Applying the proper filters, SDK configuration, and rate limits is an iterative and on-going process. Sentry provides several tools to increase your visibility into the events and issues aggregating in your streams. Let’s see how they can be leveraged to manage your streams.

> How can I see a breakdown of incoming events?

Opening the Stats view from the left side navigation bar displays details about the total number of events Sentry has received across your entire organization over the last week. The report breaks down the events by project into three categories:

  • Accepted: events processed and persisted displayed in your event and issue streams.
  • Rate Limited: events that Sentry threw away due to the limit being hit
  • Filtered: events that were blocked based on your inbound filter rules.


Clicking on a project name will open the project settings view where you can manage the project’s Inbound Filtering and Rate Limiting.

> What are my busiest projects?

The Discover view provides a flexible query builder to query event data cross-project.

  • Open the Discover view from the left side navigation bar
  • From the top-level filter bar, select View All Projects from the project drop-down and apply the desired date range
  • Build, Run, and Save the following query:

Busiest Projects

NOTE: Queries in Discover are executed against a subset of events defined in the top-level filter bar based on selected projects and date range. The Projects drop-down allows you to search for events across:

  • My Projects: all projects that you are assigned to via team-membership within the organization
  • All Projects: all projects within the organization (requires owner permission role)
  • Subset of selected projects

Project Filter

> What issues are consuming my quota?

  • Navigate to the Discover view
  • From the top-level filter bar, select View All Projects from the project drop-down and apply the desired date range
  • Build, Run, and Save the following query
  • Notice that you can open an issue details page by clicking on the issue id link

Busiest Issues

  • Alternatively, you can sort the Issues table by issue Frequency

Issue Frequency

> How to set proper rate limits?

A good way to set a project rate limit is by figuring out the expected event volume based on past traffic. Let’s look at an example:

Calculating rate limits

  • Open the project DSN key configuration under [Project Settings] > Client Keys > [Configure]
  • Take a look at the KEY USAGE IN THE LAST 30 DAYS graph. Max daily rate in the last month is < 326K
  • Based on that, we can define a ceiling daily max value of ~330K, which is ~13,750 events an hour, or ~230 events a minute.
  • Notice that you can set a daily, hourly, or minute-based rate limit. We’d recommend using a minute based rate to avoid situations where a random event spike might exhaust your daily or hourly set quota and leave you blind for a long while.
  • You can always go back, check the graph to see the number of events dropped due to rate limiting and revisit your settings.

Revisit rate limits

> Spike Protection was activated — what should I do?

You received an email notifying you that Spike Protection was triggered and applied to your account.

Spike Protection Email

Many times an unexpected spike is caused by a new error (or errors) introduced into your code with a new release version. Here are ways you can search for these errors:

  • Open the Events view from the left side navigation bar.
  • Select View All Projects from the Project drop-down to see events from all projects in your org.
  • Find the spike in the events timeline graph and mark the range with your cursor. Notice the events timeline and date filter (on the top filter bar) zooms into the selected date range. Event Spike Range

  • Now, you can use Discover to query the set of events that happened during the spike.
  • Run the query below to see the busiest issues that contributed to the spike. Issues in Spike Range

  • Open an issue details page by clicking on the issue id link. If it’s a real issue - assign it to a project team member to resolve it; otherwise - discard it.

Also, consider doing the following:

  • Set better rate limits on the DSN keys associated with the spike related projects.
  • If it’s a specific release version that has gone bad, add the version identifier to the project’s Inbound filters to avoid accepting events from that release.