Set OTEL_TRACES_SAMPLER to always on (#552)

* Add host detector * Lint * Remove Telemetry type * Set default sampler * Update release notes * Lint * Fix test
signalfx · Nov 25, 2024 · efe97b0 · efe97b0
1 parent 9ea7b96
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diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
@@ -19,19 +19,20 @@ Summary of changes between Splunk OTel Python major versions 1 and 2.
 
 ## Environment Variables
 
-| Variable                              | v2 default | v1 -> v2 changes                     | Description                                                                                                        |
-|---------------------------------------|------------|--------------------------------------|--------------------------------------------------------------------------------------------------------------------|
-| SPLUNK_ACCESS_TOKEN                   |            | None                                 | Adds token to requests to enable direct ingest (for skipping the collector)                                        |
-| OTEL_METRICS_ENABLED                  | true       | None                                 | Causes metrics to be configured (with an otlp-grpc metric exporter and a SystemMetricInstrumentor)                 |
-| OTEL_METRICS_EXPORTER                 | otlp       | Hard coded in v1, configurable in v2 | Indicates the metrics exporter                                                                                     |
-| OTEL_TRACE_ENABLED                    | true       | None                                 | Causes tracing to be configured and instrumentors loaded                                                           |
-| OTEL_TRACES_EXPORTER                  | otlp       | None                                 | Indicates the traces exporter                                                                                      |
-| OTEL_PYTHON_DISABLED_INSTRUMENTATIONS |            | None                                 | Disables instrumentations by entrypoint name                                                                       |
-| SPLUNK_PROFILER_ENABLED               | false      | None                                 | Causes the Splunk profiler to start polling at startup                                                             |
-| OTEL_SPAN_LINK_COUNT_LIMIT            | 1000       | None                                 | Sets the maximum allowed span link count                                                                           |
-| OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT     | 12000      | None                                 | Sets the maximum allowed attribute value size                                                                      |
-| SPLUNK_TRACE_RESPONSE_HEADER_ENABLED  | true       | None                                 | Causes a ServerTimingReponsePropagator to be configured if true (injects tracecontext headers into HTTP responses) |
-| OTEL_EXPERIMENTAL_RESOURCE_DETECTORS  | host       | Not set in v1                        | Causes a host resource detector to be configured to set telemetry attributes                                       |
+| Variable                              | v2 default | v1 -> v2 changes                                               | Description                                                                                                        |
+|---------------------------------------|------------|----------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------|
+| SPLUNK_ACCESS_TOKEN                   |            | None                                                           | Adds token to requests to enable direct ingest (for skipping the collector)                                        |
+| OTEL_METRICS_ENABLED                  | true       | None                                                           | Causes metrics to be configured (with an otlp-grpc metric exporter and a SystemMetricInstrumentor)                 |
+| OTEL_METRICS_EXPORTER                 | otlp       | Hard coded in v1, configurable in v2                           | Indicates the metrics exporter                                                                                     |
+| OTEL_TRACE_ENABLED                    | true       | None                                                           | Causes tracing to be configured and instrumentors loaded                                                           |
+| OTEL_TRACES_EXPORTER                  | otlp       | None                                                           | Indicates the traces exporter                                                                                      |
+| OTEL_PYTHON_DISABLED_INSTRUMENTATIONS |            | None                                                           | Disables instrumentations by entrypoint name                                                                       |
+| SPLUNK_PROFILER_ENABLED               | false      | None                                                           | Causes the Splunk profiler to start polling at startup                                                             |
+| OTEL_SPAN_LINK_COUNT_LIMIT            | 1000       | None                                                           | Sets the maximum allowed span link count                                                                           |
+| OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT     | 12000      | None                                                           | Sets the maximum allowed attribute value size                                                                      |
+| SPLUNK_TRACE_RESPONSE_HEADER_ENABLED  | true       | None                                                           | Causes a ServerTimingReponsePropagator to be configured if true (injects tracecontext headers into HTTP responses) |
+| OTEL_EXPERIMENTAL_RESOURCE_DETECTORS  | host       | Not set in v1                                                  | Causes a host resource detector to be configured to set telemetry attributes                                       |
+| OTEL_TRACES_SAMPLER                   | always_on  | Not set in v1 (took upstream default of parentbased_always_on) |                                                                                                                    |
 
 ## Auto-instrumentation
 

diff --git a/src/splunk_otel/env.py b/src/splunk_otel/env.py
@@ -28,6 +28,7 @@
     "OTEL_SPAN_LINK_COUNT_LIMIT": "1000",
     "OTEL_ATTRIBUTE_VALUE_LENGTH_LIMIT": "12000",
     "OTEL_EXPERIMENTAL_RESOURCE_DETECTORS": "host",
+    "OTEL_TRACES_SAMPLER": "always_on",
 }
 
 OTEL_TRACE_ENABLED = "OTEL_TRACE_ENABLED"

diff --git a/tests/ott_trace_loop.py b/tests/ott_trace_loop.py
@@ -1,5 +1,4 @@
 from oteltest.telemetry import count_spans, extract_leaves, get_attribute
-
 from ott_lib import project_path, trace_loop
 
 NUM_SPANS = 12

diff --git a/tests/test_distro.py b/tests/test_distro.py
@@ -20,7 +20,7 @@ def test_distro_env():
     env_store = {}
     configure_distro(env_store)
     assert env_store["OTEL_TRACES_EXPORTER"] == "otlp"
-    assert len(env_store) == 12
+    assert len(env_store) == 14
 
 
 def test_access_token():