Tail-based sampling
Elastic Stack
Most options on this page are supported by all APM Server deployment methods when writing to Elasticsearch. If you are using a different output, tail-based sampling is not supported.
Tail-based sampling configuration options.
Example config file:
apm-server:
host: "localhost:8200"
rum:
enabled: true
output:
elasticsearch:
hosts: ElasticsearchAddress:9200
max_procs: 4
Configure and customize Fleet-managed APM settings directly in Kibana:
- In Kibana, find Fleet in the main menu or use the global search field.
- Under the Agent policies tab, select the policy you would like to configure.
- Find the Elastic APM integration and select Actions > Edit integration.
- Look for these options under Tail-based sampling.
See Tail-based sampling to learn more.
Set to true to enable tail based sampling. Disabled by default. (bool)
| APM Server binary | sampling.tail.enabled |
| Fleet-managed | Enable tail-based sampling |
Synchronization interval for multiple APM Servers. Should be in the order of tens of seconds or low minutes. Default: 1m (1 minute). (duration)
| APM Server binary | sampling.tail.interval |
| Fleet-managed | Interval |
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)
| APM Server binary | sampling.tail.policies |
| Fleet-managed | Policies |
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.
A value of 0GB (or equivalent) does not set a concrete limit, but rather allows the APM Server to align its disk usage with the disk size. APM server uses up to 80% of the disk size limit on the disk where the local tail-based sampling database is located. The last 20% of disk will not be used by APM Server. It is the recommended value as it automatically scales with the disk size.
If this is not desired, a concrete GB value can be set for the maximum amount of disk used for tail-based sampling.
If the configured storage limit is insufficient, it logs "configured limit reached". The event will bypass sampling and will always be indexed when storage limit is reached.
Default: 0GB. (text)
| APM Server binary | sampling.tail.storage_limit |
| Fleet-managed | Storage limit |
See Tail-based sampling to learn more.
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)
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)
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)
The service name for events to match a policy. (string)
The service environment for events to match a policy. (string)