Configure tail-based sampling

Enable tail-based sampling with Enable tail-based sampling. When enabled, trace events are mapped to sampling policies. Each sampling policy must specify a sample rate, and can optionally specify other conditions. All of the policy conditions must be true for a trace event to match it.

Trace events are matched to policies in the order specified. Each policy list must conclude with a default policy — one that only specifies a sample rate. This default policy is used to catch remaining trace events that don’t match a stricter policy. Requiring this default policy ensures that traces are only dropped intentionally. If you enable tail-based sampling and send a transaction that does not match any of the policies, APM Server will reject the transaction with the error no matching policy.

This example defines three tail-based sampling polices:

- sample_rate: 1 
  service.environment: production
  trace.name: "GET /very_important_route"
- sample_rate: .01 
  service.environment: production
  trace.name: "GET /not_important_route"
- sample_rate: .1 

Top-level tail-based sampling settings:

Set to true to enable tail based sampling. Disabled by default. (bool)

Synchronization interval for multiple APM Servers. Should be in the order of tens of seconds or low minutes. Default: 1m (1 minute). (duration)

Criteria used to match a root transaction to a sample rate.

Policies map trace events to a sample rate. Each policy must specify a sample rate. Trace events are matched to policies in the order specified. All policy conditions must be true for a trace event to match. Each policy list should conclude with a policy that only specifies a sample rate. This final policy is used to catch remaining trace events that don’t match a stricter policy. ([]policy)

The amount of storage space allocated for trace events matching tail sampling policies. Caution: Setting this limit higher than the allowed space may cause APM Server to become unhealthy.

If the configured storage limit is insufficient, it logs "configured storage limit reached". The event will bypass sampling and will always be indexed when storage limit is reached.

Default: 3GB. (text)

Policy settings:

sample_rate

The sample rate to apply to trace events matching this policy. Required in each policy.

The sample rate must be greater than or equal to 0 and less than or equal to 1. For example, a sample_rate of 0.01 means that 1% of trace events matching the policy will be sampled. A sample_rate of 1 means that 100% of trace events matching the policy will be sampled. (int)

trace.name

The trace name for events to match a policy. A match occurs when the configured trace.name matches the transaction.name of the root transaction of a trace. A root transaction is any transaction without a parent.id. (string)

trace.outcome

The trace outcome for events to match a policy. A match occurs when the configured trace.outcome matches a trace’s event.outcome field. Trace outcome can be success, failure, or unknown. (string)

service.name

The service name for events to match a policy. (string)

service.environment

The service environment for events to match a policy. (string)