chore(test): Improve tests

.trivyignore

@@ -1,10 +1,6 @@
-# ignore CVE introduced by python3-gunicorn
-CVE-2022-40897
 # pypa/setuptools: Remote code execution via download
 CVE-2024-6345
 # pebble: Calling Decoder.Decode on a message which contains deeply nested structures can cause a panic due to stack exhaustion
 CVE-2024-34156
-# pebble: Go stdlib
-CVE-2024-45338
 # go-app: Go crypto lib
-CVE-2024-45337 
+CVE-2024-45337

tests/integration/integrations/test_tracing.py

@@ -20,20 +20,19 @@
 
 
 @pytest.mark.parametrize(
-    "tracing_app, port",
+    "tracing_app_fixture, port",
     [
         ("flask_tracing_app", 8000),
         ("django_tracing_app", 8000),
         ("fastapi_tracing_app", 8080),
         ("go_tracing_app", 8080),
     ],
-    indirect=["tracing_app"],
 )
 @pytest.mark.skip_juju_version("3.4")  # Tempo only supports Juju>=3.4
 async def test_workload_tracing(
     ops_test: OpsTest,
     model: Model,
-    tracing_app: Application,
+    tracing_app_fixture: str,
     port: int,
     request: pytest.FixtureRequest,
     get_unit_ips,
@@ -49,6 +48,7 @@ async def test_workload_tracing(
     except Exception as e:
         logger.info(f"Tempo is already deployed  {e}")
 
+    tracing_app = request.getfixturevalue(tracing_app_fixture)
     idle_list = [tracing_app.name]
 
     if tracing_app.name != "flask-tracing-k8s":

tests/unit/flask/constants.py

@@ -26,6 +26,33 @@
     }
 }
 
+LAYER_WITH_TRACING = {
+    "services": {
+        "flask": {
+            "override": "replace",
+            "startup": "enabled",
+            "command": f"/bin/python3 -m gunicorn -c /flask/gunicorn.conf.py app:app -k sync",
+            "after": ["statsd-exporter"],
+            "user": "_daemon_",
+            "environment": {
+                "OTEL_EXPORTER_OTLP_ENDPOINT": "http://test-ip:4318",
+                "OTEL_SERVICE_NAME": "flask-k8s",
+            },
+        },
+        "statsd-exporter": {
+            "override": "merge",
+            "command": (
+                "/bin/statsd_exporter --statsd.mapping-config=/statsd-mapping.conf "
+                "--statsd.listen-udp=localhost:9125 "
+                "--statsd.listen-tcp=localhost:9125"
+            ),
+            "summary": "statsd exporter service",
+            "startup": "enabled",
+            "user": "_daemon_",
+        },
+    }
+}
+
 LAYER_WITH_WORKER = {
     "services": {
         "flask": {

tests/unit/flask/test_tracing.py

@@ -36,3 +36,22 @@ def test_tracing_relation(harness: Harness):
     service_env = container.get_plan().services["flask"].environment
     assert service_env["OTEL_EXPORTER_OTLP_ENDPOINT"] == "http://test-ip:4318"
     assert service_env["OTEL_SERVICE_NAME"] == "flask-k8s"
+
+
+def test_tracing_not_activated(harness: Harness):
+    """
+    arrange: Deploy the charm without a relation to the Tempo charm.
+    act: Run all initial hooks.
+    assert: The flask service should not have the environment variables OTEL_EXPORTER_OTLP_ENDPOINT, OTEL_SERVICE_NAME.
+    """
+    harness.set_model_name("flask-model")
+
+    container = harness.model.unit.get_container(FLASK_CONTAINER_NAME)
+    container.add_layer("a_layer", DEFAULT_LAYER)
+
+    harness.begin_with_initial_hooks()
+
+    assert harness.model.unit.status == ops.ActiveStatus()
+    service_env = container.get_plan().services["flask"].environment
+    assert service_env.get("OTEL_EXPORTER_OTLP_ENDPOINT", None) is None
+    assert service_env.get("OTEL_SERVICE_NAME", None) is None

tests/unit/flask/test_webserver.py

@@ -19,11 +19,12 @@
 from paas_charm.charm_state import CharmState
 from paas_charm.utils import enable_pebble_log_forwarding
 
-from .constants import DEFAULT_LAYER, FLASK_CONTAINER_NAME
+from .constants import DEFAULT_LAYER, FLASK_CONTAINER_NAME, LAYER_WITH_TRACING
 
 GUNICORN_CONFIG_TEST_PARAMS = [
     pytest.param(
         {"workers": 10},
+        DEFAULT_LAYER,
         textwrap.dedent(
             f"""\
                 bind = ['0.0.0.0:8000']
@@ -37,6 +38,7 @@
     ),
     pytest.param(
         {"threads": 2, "timeout": 3, "keepalive": 4},
+        DEFAULT_LAYER,
         textwrap.dedent(
             f"""\
                 bind = ['0.0.0.0:8000']
@@ -50,12 +52,41 @@
         ),
         id="threads=2,timeout=3,keepalive=4",
     ),
+    pytest.param(
+        {},
+        LAYER_WITH_TRACING,
+        textwrap.dedent(
+            f"""\
+                bind = ['0.0.0.0:8000']
+                chdir = '/flask/app'
+                accesslog = '/var/log/flask/access.log'
+                errorlog = '/var/log/flask/error.log'
+                statsd_host = 'localhost:9125'
+                from opentelemetry import trace
+                from opentelemetry.exporter.otlp.proto.http.trace_exporter import (
+                    OTLPSpanExporter,
+                )
+                from opentelemetry.sdk.trace import TracerProvider
+                from opentelemetry.sdk.trace.export import BatchSpanProcessor
+
+                def post_fork(server, worker):
+                    trace.set_tracer_provider(TracerProvider())
+                    span_processor = BatchSpanProcessor(OTLPSpanExporter())
+                    trace.get_tracer_provider().add_span_processor(span_processor)
+                """
+        ),
+        id="with-tracing",
+    ),
 ]
 
 
-@pytest.mark.parametrize("charm_state_params, config_file", GUNICORN_CONFIG_TEST_PARAMS)
+@pytest.mark.parametrize("charm_state_params, layer, config_file", GUNICORN_CONFIG_TEST_PARAMS)
 def test_gunicorn_config(
-    harness: Harness, charm_state_params, config_file, database_migration_mock
+    harness: Harness,
+    charm_state_params,
+    layer,
+    config_file,
+    database_migration_mock,
 ) -> None:
     """
     arrange: create the Gunicorn webserver object with a controlled charm state generated by the
@@ -66,7 +97,7 @@ def test_gunicorn_config(
     harness.begin()
     container: ops.Container = harness.model.unit.get_container(FLASK_CONTAINER_NAME)
     harness.set_can_connect(FLASK_CONTAINER_NAME, True)
-    container.add_layer("default", DEFAULT_LAYER)
+    container.add_layer("default", layer)
 
     charm_state = CharmState(
         framework="flask",