Autogenerated metrics

Overview

This topic explains the metrics LaunchDarkly automatically generates from SDK events and how you can use them to monitor the health of your applications.

Metric events

An “event” happens when someone takes an action in your app, such as clicking on a button, or when a system takes an action, such as loading a page. Your SDKs send these metric events to LaunchDarkly, where, for certain event kinds, LaunchDarkly can automatically create metrics from those events. You can use these metrics with experiments and guarded rollouts to track how your flag changes affect your customers’ behavior.

LaunchDarkly autogenerates metrics from events that are sent:

from AI SDKs used in conjunction with AI Configs
from telemetry integrations, such as the JavaScript telemetry integration, used in conjunction with JavaScript-based client-side SDKs
during document load, for browser apps, if you are using the Observability plugin
as part of OpenTelemetry traces using the OpenTelemetry feature for server-side SDKs

Autogenerated metrics are marked on the Metrics list with an autogenerated tag. You can view the events that autogenerated these metrics from the Metrics list by clicking View, then Events.

To learn more, read Metric events and Metric analysis.

Randomization units for autogenerated metrics

LaunchDarkly sets the randomization unit for autogenerated metrics to your account’s default context kind for experiments. For most accounts, the default context kind for experiments is user. However, you may have updated your default context kind to account, device, or some other context kind you use in experiments most often. To learn how to change the default context kind for experiments, read Map randomization units to context kinds.

All autogenerated metrics are designed to work with a randomization unit of either user or request. Depending on your account’s default context kind for experiments, you may need to manually update the randomization unit for autogenerated metrics as needed. The recommended randomization units for each autogenerated metric are listed in the tables below. To learn how to manually update the randomization unit for a metric, read Edit metrics.

To learn more, read Randomization units.

Metrics autogenerated from AI SDK events

An AI Config is a resource that you create in LaunchDarkly and then use to customize, test, and roll out new large language models (LLMs) within your generative AI applications. As soon as you start using AI Configs in your application, you can track how your AI model generation is performing, and your AI SDKs begin sending events to LaunchDarkly.

AI SDK events are prefixed with $ld:ai and LaunchDarkly automatically generates metrics from these events.

Some events generate multiple metrics that measure different aspects of the same event. For example, the $ld:ai:feedback:user:positive event generates a metric that measures the average number of positive feedback events per user, and a metric that measures the percentage of users that generated positive feedback.

This table explains the metrics that LaunchDarkly autogenerates from AI SDK events:

Event key, metric kind, and randomization unit	Metric definition	Metric name and description
Event key: $ld:ai:feedback:user:positive Metric kind: Custom conversion count Randomization unit: User	Measurement method: Count Unit aggregation method: Sum Analysis method: Average Success criterion: Higher is better Units without events: Include units that did not send any events and set their value to 0	Name: Positive AI feedback count Description: Average number of positive feedback events per context Example usage: Running an experiment to find out which variation causes more users to click “thumbs up”
Event key: $ld:ai:feedback:user:positive Metric kind: Custom conversion binary Randomization unit: Request	Measurement method: Occurrence Unit aggregation method: Average Analysis method: Average Success criterion: Higher is better Units without events: Include units that did not send any events and set their value to 0	Name: Positive AI feedback rate Description: Percentage of contexts that generated positive AI feedback Example usage: Running a guarded rollout to make sure there is a positive feedback ratio throughout the rollout
Event key: $ld:ai:feedback:user:negative Metric kind: Custom conversion count Randomization unit: User	Measurement method: Count Unit aggregation method: Sum Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: Negative AI feedback count Description: Average number of negative feedback events per context Example usage: Running an experiment to find out which variation causes more users to click “thumbs down”
Event key: $ld:ai:feedback:user:negative Metric kind: Custom conversion binary Randomization unit: User	Measurement method: Occurrence Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: Negative AI feedback rate Description: Percentage of contexts that generated negative AI feedback Example usage: Running an experiment to find out which variation causes more users to click “thumbs down”
Event key: $ld:ai:tokens:input Metric kind: Numeric Randomization unit: Request	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events	Name: Average input tokens per AI completion Description: For example, for a chatbot, this might indicate user engagement Example usage: Running an experiment to find out which variation results in fewer input tokens, reducing cost
Event key: $ld:ai:tokens:output Metric kind: Numeric Randomization unit: Request	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events	Name: Average output tokens per AI completion Description: Indicator of cost, when charged by token usage Example usage: Running an experiment to find out which variation results in fewer output tokens, reducing cost
Event key: $ld:ai:tokens:total Metric kind: Numeric Randomization unit: Request	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events	Name: Average total tokens per AI completion Description: Indicator of cost, when charged by token usage Example usage: Running an experiment to find out which variation results in fewer total tokens, reducing cost
Event key: $ld:ai:duration:total Metric kind: Numeric Randomization unit: Request	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events	Name: Average AI completion time Description: Time required for LLM to finish a completion Example usage: Running an experiment to find out which variation results in faster user completion, improving engagement
Event key: $ld:ai:generation:success Metric kind: Custom conversion count Randomization unit: User	Measurement method: Count Unit aggregation method: Sum Analysis method: Average Success criterion: Higher is better Units without events: Include units that did not send any events and set their value to 0	Name: AI completion success count Description: Counter for successful LLM completion requests Example usage: Running an experiment to find out which variation results in more user completion requests (“chattiness”), improving engagement
Event key: $ld:ai:generation:error Metric kind: Custom conversion count Randomization unit: Request	Measurement method: Occurrence Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: AI completion error count Description: Counter for erroneous LLM completion requests Example usage: Running a guarded rollout to make sure the change doesn’t result in a higher error rate
Event key: $ld:ai:generation:error Metric kind: Custom Randomization unit: User	Measurement method: Occurrence Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: AI completion error count Description: Counter for erroneous LLM completion requests Example usage: Running a guarded rollout to make sure the change doesn’t result in a higher error rate
Event key: $ld:ai:generation:error Metric kind: Custom Randomization unit: User	Measurement method: Count Unit aggregation method: Sum Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: AI completion error count Description: Counter for erroneous LLM completion requests Example usage: Running a guarded rollout to make sure the change doesn’t result in a higher number of errors
Event key: $ld:ai:tokens:ttf Metric kind: Numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events	Name: Average time to first token for AI requests Description: Time required for LLM to generate first token Example usage: Running a guarded rollout to make sure the change doesn’t result in longer token generation times

As an example, the autogenerated metric in the first row of the above table tracks the average number of positive feedback ratings per user.

Here is what the metric setup looks like in the LaunchDarkly user interface:

Metrics autogenerated from telemetry integration events

The LaunchDarkly telemetry integrations provide error monitoring and metric collection. Each telemetry integration is a separate package, which you install in addition to the LaunchDarkly SDK. After you initialize the telemetry integration, you register the LaunchDarkly SDK client with the telemetry instance. The instance collects and sends telemetry data to LaunchDarkly, where you can review metrics, events, and errors from your application.

Telemetry integration events are prefixed with $ld:telemetry and LaunchDarkly automatically generates metrics from these events.

This table explains the metrics that LaunchDarkly autogenerates from events recorded by the telemetry integration for LaunchDarkly browser SDKs:

Event key, metric kind, and randomization unit	Metric definition	Metric name and description
Event key: $ld:telemetry:error Metric kind: Custom conversion binary Randomization unit: User	Measurement method: Occurrence Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: Percentage of users with errors (LaunchDarkly) Description: Measures the percentage of contexts that encountered an error at least once, as reported by the LaunchDarkly telemetry integration. Useful when running a guarded rollout. Example usage: Running a guarded rollout to make sure the change doesn’t result in a higher error rate

Metrics autogenerated from observability events

The LaunchDarkly observability plugins provide error monitoring and metric collection for errors, web vitals, and document loading in your browser application. The functionality is in separate plugins, which you enable in the initialization options for the LaunchDarkly SDK. The observability plugins collect and send data to LaunchDarkly, where you can review metrics, events, and errors from your application.

Like the telemetry integration events, the observability events are prefixed with $ld:telemetry and LaunchDarkly automatically generates metrics from these events.

This table explains the metrics that LaunchDarkly autogenerates from events recorded by the observability plugins for LaunchDarkly browser SDKs:

Event key, metric kind, and randomization unit	Metric definition	Metric name and description
Event key: $ld:telemetry:metric:cls Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: Average Cumulative Layout Shift (CLS) per context (LaunchDarkly) Description: Measures the average largest burst per context of layout shift scores for every unexpected layout shift that occurs during the entire lifecycle of a page. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:cls Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P95 Cumulative Layout Shift (CLS) per context (LaunchDarkly) Description: Measures the 95th percentile largest burst per context of layout shift scores for every unexpected layout shift that occurs during the entire lifecycle of a page. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:cls Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P99 Cumulative Layout Shift (CLS) per context (LaunchDarkly) Description: Measures the 99th percentile largest burst per context of layout shift scores for every unexpected layout shift that occurs during the entire lifecycle of a page. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric: document_load Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: Average Document Load Latency per context (LaunchDarkly) Description: Measures the average DOM load duration in milliseconds per context Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric: document_load Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P95 Document Load Latency per context (LaunchDarkly) Description: Measures the 95th percentile DOM load duration in milliseconds per context Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric: document_load Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P99 Document Load Latency per context (LaunchDarkly) Description: Measures the 99th percentile DOM load duration in milliseconds per context Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:error Metric kind: Custom conversion binary Randomization unit: User	Measurement method: Occurrence Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: Percentage of users with errors (LaunchDarkly) Description: Measures the percentage of contexts that encountered an error at least once. This metric is autogenerated by an initial `$ld:telemetry:session:init` event and populated by subsequent `$ld:telemetry:error` events. This means you can use the metric even if your app has not yet generated any errors. Example usage: Running a guarded rollout to make sure the error change doesn’t result in a higher error rate
Event key: $ld:telemetry:metric:fcp Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: Average First Contentful Paint (FCP) per context (LaunchDarkly) Description: Measures the average time in milliseconds per context between first navigation to a page and when any part of the page’s content is rendered. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:fcp Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P95 First Contentful Paint (FCP) per context (LaunchDarkly) Description: Measures the 95th percentile time in milliseconds per context between first navigation to a page and when any part of the page’s content is rendered. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:fcp Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P99 First Contentful Paint (FCP) per context (LaunchDarkly) Description: Measures the 99th percentile time in milliseconds per context between first navigation to a page and when any part of the page’s content is rendered. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:inp Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: Average Interaction to Next Paint (INP) per context (LaunchDarkly) Description: Measures the average response time in milliseconds per context of all click, tap, and keyboard interactions during the lifespan of a visit to a page. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:inp Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P95 Interaction to Next Paint (INP) per context (LaunchDarkly) Description: Measures the 95th percentile response time in milliseconds per context of all click, tap, and keyboard interactions during the lifespan of a visit to a page. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:inp Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P99 Interaction to Next Paint (INP) per context (LaunchDarkly) Description: Measures the 99th percentile response time in milliseconds per context of all click, tap, and keyboard interactions during the lifespan of a visit to a page. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:lcp Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: Average Largest Contentful Paint (LCP) per context (LaunchDarkly) Description: Measures the average time in milliseconds per context to render the largest image, text block, or video visible when first navigating to a page Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:lcp Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P95 Largest Contentful Paint (LCP) per context (LaunchDarkly) Description: Measures the 95th percentile time in milliseconds per context to render the largest image, text block, or video visible when first navigating to a page Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:lcp Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P99 Largest Contentful Paint (LCP) per context (LaunchDarkly) Description: Measures the 99th percentile time in milliseconds per context to render the largest image, text block, or video visible when first navigating to a page Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:ttfb Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: Average Time to First Byte (TTFB) per context (LaunchDarkly) Description: Measures the average time in milliseconds per context between the request for a resource and when the first byte of a response begins to arrive. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:ttfb Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P95 Time to First Byte (TTFB) per context (LaunchDarkly) Description: Measures the 95th percentile time in milliseconds per context between the request for a resource and when the first byte of a response begins to arrive. Example usage: Observing the latency of interactions an end user makes with your application
Event key: $ld:telemetry:metric:ttfb Metric kind: Custom numeric Randomization unit: User	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events from the analysis	Name: P99 Time to First Byte (TTFB) per context (LaunchDarkly) Description: Measures the 99th percentile time in milliseconds per context between the request for a resource and when the first byte of a response begins to arrive. Example usage: Observing the latency of interactions an end user makes with your application

Metrics autogenerated from server-side SDKs using OpenTelemetry

LaunchDarkly’s SDKs support instrumentation for OpenTelemetry traces. Traces provide an overview of how your application handles requests. For example, traces may show that a particular feature flag was evaluated for a particular context as part of a given HTTP request. To learn more, read OpenTelemetry and Sending OpenTelemetry traces to LaunchDarkly.

OpenTelemetry events are prefixed with otel and LaunchDarkly automatically generates metrics from these events.

This table explains the metrics that LaunchDarkly autogenerates from OpenTelemetry traces:

Event key, metric kind, and randomization unit	Metric definition	Metric name and description
Event key: otel.http.error Metric kind: Custom conversion binary Randomization unit: User	Measurement method: Occurrence Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: User HTTP error rate (OpenTelemetry) Description: Measures the percentage of users that encountered an error inside HTTP spans at least once, as reported by OpenTelemetry. Useful when running a guarded rollout.
Event key: otel.http.5XX Metric kind: Custom conversion binary Randomization unit: User	Measurement method: Occurrence Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: User HTTP 5XX response rate (OpenTelemetry) Description: Measures the percentage of users that encountered an HTTP 5XX response at least once, as reported by OpenTelemetry. Useful when running a guarded rollout.
Event key: otel.exception Metric kind: Custom conversion binary Randomization unit: User	Measurement method: Occurrence Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Include units that did not send any events and set their value to 0	Name: User non-HTTP exception rate (OpenTelemetry) Description: Measures the percentage of users that encountered an exception outside of HTTP spans at least once, as reported by OpenTelemetry. Useful when running a guarded rollout.
Event key: otel.http.latency Metric kind: Custom numeric Randomization unit: Request	Measurement method: Value/size Unit aggregation method: Average Analysis method: Average Success criterion: Lower is better Units without events: Exclude units that did not send any events	Name: Average request latency (OpenTelemetry) Description: Measures the average request latency, as reported by OpenTelemetry. Useful when running a guarded rollout. For best results, use a ‘request’ randomization unit and send ‘request’ contexts.
Event key: otel.http.latency Metric kind: Custom numeric Randomization unit: Request	Measurement method: Value/size Unit aggregation method: Average Analysis method: P95 Success criterion: Lower is better Units without events: Exclude units that did not send any events	Name: P95 request latency (OpenTelemetry) Description: Measures the 95th percentile request latency, as reported by OpenTelemetry. For many applications, this represents the experience for most requests. You can adjust the percentile to fit your application’s needs. Useful when running a guarded rollout. For best results, use a ‘request’ randomization unit and send ‘request’ contexts.
Event key: otel.http.latency Metric kind: Custom numeric Randomization unit: Request	Measurement method: Value/size Unit aggregation method: Average Analysis method: P99 Success criterion: Lower is better Units without events: Exclude units that did not send any events	Name: P99 request latency (OpenTelemetry) Description: Measures the 99th percentile request latency, as reported by OpenTelemetry. For many applications, this represents the worst-case experiences. You can adjust the percentile to fit your application’s needs. Useful when running a guarded rollout. For best results, use a ‘request’ randomization unit and send ‘request’ contexts.