add span_compression_enabled setting

closes elastic#1428

Author: beniwohli

docs/configuration.asciidoc

@@ -691,6 +691,24 @@ To disable stack trace collection for spans completely, set the value to `0`.
 Except for the special values `-1` and `0`,
 this setting has to be provided in *<<config-format-duration, duration format>>*.
 
+[float]
+[[config-span-compression-enabled]]
+==== `span_compression_enabled`
+
+<<dynamic-configuration, image:./images/dynamic-config.svg[] >>
+
+[options="header"]
+|============
+| Environment                            | Django/Flask               | Default
+| `ELASTIC_APM_SPAN_COMPRESSION_ENABLED` | `SPAN_COMPRESSION_ENABLED` | `False`
+|============
+
+Enable/disable span compression.
+
+If enabled, the agent will compress very short, repeated spans into a single span,
+which is beneficial for storage and processing requirements.
+Some information is lost in this process, e.g. exact durations of each compressed span.
+
 [float]
 [[config-span-compression-exact-match-max_duration]]
 ==== `span_compression_exact_match_max_duration`

elasticapm/conf/__init__.py

@@ -578,14 +578,15 @@ class Config(_ConfigBase):
         ],
         type=int,
     )
+    span_compression_enabled = _BoolConfigValue("SPAN_COMPRESSION_ENABLED", default=False)
     span_compression_exact_match_max_duration = _ConfigValue(
-        "span_compression_exact_match_max_duration",
+        "SPAN_COMPRESSION_EXACT_MATCH_MAX_DURATION",
         default=50,
         validators=[duration_validator],
         type=int,
     )
     span_compression_same_kind_max_duration = _ConfigValue(
-        "span_compression_exact_match_max_duration",
+        "SPAN_COMPRESSION_SAME_KIND_MAX_DURATION",
         default=5,
         validators=[duration_validator],
         type=int,

elasticapm/traces.py

@@ -583,7 +583,12 @@ def is_exact_match(self, other_span: SpanType) -> bool:
         return bool(self.name == other_span.name and self.is_same_kind(other_span))
 
     def is_compression_eligible(self) -> bool:
-        return self.leaf and not self.dist_tracing_propagated and self.outcome in (None, constants.OUTCOME.SUCCESS)
+        """
+        Determine if this span is eligible for compression.
+        """
+        if self.tracer.config.span_compression_enabled:
+            return self.leaf and not self.dist_tracing_propagated and self.outcome in (None, constants.OUTCOME.SUCCESS)
+        return False
 
     def end(self, skip_frames: int = 0, duration: Optional[float] = None):
         """

tests/client/span_compression_tests.py

@@ -35,7 +35,13 @@
 
 @pytest.mark.parametrize(
     "elasticapm_client",
-    [{"span_compression_same_kind_max_duration": "5ms", "span_compression_exact_match_max_duration": "5ms"}],
+    [
+        {
+            "span_compression_enabled": True,
+            "span_compression_same_kind_max_duration": "5ms",
+            "span_compression_exact_match_max_duration": "5ms",
+        }
+    ],
     indirect=True,
 )
 def test_exact_match(elasticapm_client):
@@ -73,7 +79,13 @@ def test_exact_match(elasticapm_client):
 
 @pytest.mark.parametrize(
     "elasticapm_client",
-    [{"span_compression_same_kind_max_duration": "5ms", "span_compression_exact_match_max_duration": "5ms"}],
+    [
+        {
+            "span_compression_enabled": True,
+            "span_compression_same_kind_max_duration": "5ms",
+            "span_compression_exact_match_max_duration": "5ms",
+        }
+    ],
     indirect=True,
 )
 def test_same_kind(elasticapm_client):
@@ -114,7 +126,13 @@ def test_same_kind(elasticapm_client):
 
 @pytest.mark.parametrize(
     "elasticapm_client",
-    [{"span_compression_same_kind_max_duration": "5ms", "span_compression_exact_match_max_duration": "5ms"}],
+    [
+        {
+            "span_compression_enabled": True,
+            "span_compression_same_kind_max_duration": "5ms",
+            "span_compression_exact_match_max_duration": "5ms",
+        }
+    ],
     indirect=True,
 )
 def test_exact_match_after_same_kind(elasticapm_client):
@@ -162,7 +180,13 @@ def test_exact_match_after_same_kind(elasticapm_client):
 
 @pytest.mark.parametrize(
     "elasticapm_client",
-    [{"span_compression_same_kind_max_duration": "5ms", "span_compression_exact_match_max_duration": "5ms"}],
+    [
+        {
+            "span_compression_enabled": True,
+            "span_compression_same_kind_max_duration": "5ms",
+            "span_compression_exact_match_max_duration": "5ms",
+        }
+    ],
     indirect=True,
 )
 def test_nested_spans(elasticapm_client):
@@ -199,7 +223,13 @@ def test_nested_spans(elasticapm_client):
 
 @pytest.mark.parametrize(
     "elasticapm_client",
-    [{"span_compression_same_kind_max_duration": "5ms", "span_compression_exact_match_max_duration": "5ms"}],
+    [
+        {
+            "span_compression_enabled": True,
+            "span_compression_same_kind_max_duration": "5ms",
+            "span_compression_exact_match_max_duration": "5ms",
+        }
+    ],
     indirect=True,
 )
 def test_buffer_is_reported_if_next_child_ineligible(elasticapm_client):
@@ -224,7 +254,13 @@ def test_buffer_is_reported_if_next_child_ineligible(elasticapm_client):
 
 @pytest.mark.parametrize(
     "elasticapm_client",
-    [{"span_compression_same_kind_max_duration": "5ms", "span_compression_exact_match_max_duration": "5ms"}],
+    [
+        {
+            "span_compression_enabled": True,
+            "span_compression_same_kind_max_duration": "5ms",
+            "span_compression_exact_match_max_duration": "5ms",
+        }
+    ],
     indirect=True,
 )
 def test_compressed_spans_not_counted(elasticapm_client):
@@ -254,3 +290,43 @@ def test_compressed_spans_not_counted(elasticapm_client):
     spans = elasticapm_client.events[SPAN]
     assert len(spans) == transaction["span_count"]["started"] == 1
     assert transaction["span_count"]["dropped"] == 0
+
+
+@pytest.mark.parametrize(
+    "elasticapm_client",
+    [
+        {
+            "span_compression_enabled": False,
+            "span_compression_same_kind_max_duration": "5ms",
+            "span_compression_exact_match_max_duration": "5ms",
+        }
+    ],
+    indirect=True,
+)
+def test_span_compression_disabled(elasticapm_client):
+    transaction = elasticapm_client.begin_transaction("test")
+    with elasticapm.capture_span(
+        "test",
+        span_type="a",
+        span_subtype="b",
+        span_action="c",
+        leaf=True,
+        duration=2,
+        extra={"destination": {"service": {"resource": "x"}}},
+    ) as span1:
+        assert not span1.is_compression_eligible()
+    with elasticapm.capture_span(
+        "test",
+        span_type="a",
+        span_subtype="b",
+        span_action="c",
+        leaf=True,
+        duration=3,
+        extra={"destination": {"service": {"resource": "x"}}},
+    ) as span2:
+        assert not span2.is_compression_eligible()
+    elasticapm_client.end_transaction("test")
+    spans = elasticapm_client.events[SPAN]
+    assert len(spans) == 2
+    span = spans[0]
+    assert "composite" not in span

tests/config/tests.py

@@ -438,3 +438,11 @@ def test_versioned_config_attribute_access(elasticapm_client):
     elasticapm_client.config.update("2", capture_body=True)
     val = elasticapm_client.config.start_stop_order
     assert isinstance(val, int)
+
+
+def test_config_all_upper_case():
+    c = Config.__class__.__dict__.items()
+    for field, config_value in Config.__dict__.items():
+        if not isinstance(config_value, _ConfigValue):
+            continue
+        assert config_value.env_key == config_value.env_key.upper()