Observability autogenerated metrics | LaunchDarkly

This topic describes metrics that LaunchDarkly autogenerates from observability events.

The LaunchDarkly observability session replay SDK 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 session replay plugins automatically collect and send data to LaunchDarkly, where you can review metrics, events, and errors from your application.

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

These expandable sections explain the metrics that LaunchDarkly autogenerates from events recorded by the observability plugins for LaunchDarkly browser SDKs:

Average Cumulative Layout Shift (CLS) per context (LaunchDarkly) $ld:telemetry:metric:cls

Metric kind: Custom numeric

Suggested analysis unit: User

Definition: Average event values per user, then compute the Average of those values where Lower is better

Units without events: Excluded

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

P95 Cumulative Layout Shift (CLS) per context (LaunchDarkly) $ld:telemetry:metric:cls

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P95 of those values where Lower is better

Units without events: Excluded

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

P99 Cumulative Layout Shift (CLS) per context (LaunchDarkly) $ld:telemetry:metric:cls

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P99 of those values where Lower is better

Units without events: Excluded

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

Average Document Load Latency per context (LaunchDarkly) $ld:telemetry:metric:document_load

Metric kind: Custom numeric

Suggested analysis unit: User

Definition: Average event values per user, then compute the Average of those values where Lower is better

Units without events: Excluded

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

P95 Document Load Latency per context (LaunchDarkly) $ld:telemetry:metric:document_load

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P95 of those values where Lower is better

Units without events: Excluded

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

P99 Document Load Latency per context (LaunchDarkly) $ld:telemetry:metric:document_load

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P99 of those values where Lower is better

Units without events: Excluded

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

User error rate (LaunchDarkly) $ld:telemetry:error

Metric kind: Custom conversion binary

Suggested analysis unit: User

Definition: Percent of user units that sent the event where Lower is better

Units without events: Include units and set the value to 0

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

Average First Contentful Paint (FCP) per context (LaunchDarkly) $ld:telemetry:metric:fcp

Metric kind: Custom numeric

Suggested analysis unit: User

Definition: Average event values per user, then compute the Average of those values where Lower is better

Units without events: Excluded

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

P95 First Contentful Paint (FCP) per context (LaunchDarkly) $ld:telemetry:metric:fcp

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P95 of those values where Lower is better

Units without events: Excluded

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

P99 First Contentful Paint (FCP) per context (LaunchDarkly) $ld:telemetry:metric:fcp

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P99 of those values where Lower is better

Units without events: Excluded

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

Average First Input Delay (FID) per context (LaunchDarkly) $ld:telemetry:metric:fid

Metric kind: Custom numeric

Suggested analysis unit: User

Definition: Average event values per user, then compute the Average of those values where Lower is better

Units without events: Excluded

Description: Measures the average time in milliseconds per context between a user’s first interaction (click, tap, or key press) and the time when the browser starts processing event handlers in response to that interaction.

Example usage: Observing the latency of interactions an end user makes with your application

P95 First Input Delay (FID) per context (LaunchDarkly) $ld:telemetry:metric:fid

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P95 of those values where Lower is better

Units without events: Excluded

Description: Measures the 95th percentile time, in milliseconds per context, between a user’s first interaction (click, tap, or key press) and the time when the browser starts processing event handlers in response to that interaction.

Example usage: Observing the latency of interactions an end user makes with your application

P99 First Input Delay (FID) per context (LaunchDarkly) $ld:telemetry:metric:fid

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P99 of those values where Lower is better

Units without events: Excluded

Description: Measures the 99th percentile time, in milliseconds per context, between a user’s first interaction (click, tap, or key press) and the time when the browser starts processing event handlers in response to that interaction.

Example usage: Observing the latency of interactions an end user makes with your application

Average Interaction to Next Paint (INP) per context (LaunchDarkly) $ld:telemetry:metric:inp

Metric kind: Custom numeric

Suggested analysis unit: User

Definition: Average event values per user, then compute the Average of those values where Lower is better

Units without events: Excluded

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

P95 Interaction to Next Paint (INP) per context (LaunchDarkly) $ld:telemetry:metric:inp

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P95 of those values where Lower is better

Units without events: Excluded

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

P99 Interaction to Next Paint (INP) per context (LaunchDarkly) $ld:telemetry:metric:inp

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P99 of those values where Lower is better

Units without events: Excluded

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

Average Largest Contentful Paint (LCP) per context (LaunchDarkly) $ld:telemetry:metric:lcp

Metric kind: Custom numeric

Suggested analysis unit: User

Definition: Average event values per user, then compute the Average of those values where Lower is better

Units without events: Excluded

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

P95 Largest Contentful Paint (LCP) per context (LaunchDarkly) $ld:telemetry:metric:lcp

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P95 of those values where Lower is better

Units without events: Excluded

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

P99 Largest Contentful Paint (LCP) per context (LaunchDarkly) $ld:telemetry:metric:lcp

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P99 of those values where Lower is better

Units without events: Excluded

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

Average Time to First Byte (TTFB) per context (LaunchDarkly) $ld:telemetry:metric:ttfb

Metric kind: Custom numeric

Suggested analysis unit: User

Definition: Average event values per user, then compute the Average of those values where Lower is better

Units without events: Excluded

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

P95 Time to First Byte (TTFB) per context (LaunchDarkly) $ld:telemetry:metric:ttfb

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P95 of those values where Lower is better

Units without events: Excluded

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

P99 Time to First Byte (TTFB) per context (LaunchDarkly) $ld:telemetry:metric:ttfb

Metric kind: Custom numeric

Suggested analysis unit: Request

Definition: Average event values per request, then compute the P99 of those values where Lower is better

Units without events: Excluded

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