prefect: add container-based config discovery support (#24483)

* prefect: add container-based config discovery support

* Add changelog entry for #24483

Author: vitkyrka

prefect/assets/configuration/spec.yaml

@@ -1,6 +1,13 @@
 name: Prefect
 files:
 - name: prefect.yaml
+  discovery:
+    strategies:
+    - strategy: from_ports
+      port_hints:
+      - 4200
+      candidates:
+      - prefect_url: "http://{service.host}:{port.number}/api"
   options:
   - template: init_config
     options:
@@ -146,4 +153,11 @@ files:
       - type: multi_line
         name: python_stack_trace
         pattern: '^\d{2}:\d{2}:\d{2}\.\d{3} \|'
+- name: auto_conf.yaml
+  options:
+  - template: ad_identifiers
+    overrides:
+      value.example:
+      - prefect
+  - template: auto_conf/discovery
 

prefect/changelog.d/24483.added

@@ -0,0 +1 @@
+Add container-based config discovery support.

prefect/datadog_checks/prefect/config_models/discovery.py

@@ -0,0 +1,42 @@
+# (C) Datadog, Inc. 2026-present
+# All rights reserved
+# Licensed under a 3-clause BSD style license (see LICENSE)
+
+# This file is autogenerated.
+# To change this file you should edit assets/configuration/spec.yaml and then run the following commands:
+#     ddev -x validate config -s <INTEGRATION_NAME>
+#     ddev -x validate models -s <INTEGRATION_NAME>
+
+from __future__ import annotations
+
+from collections.abc import Iterator
+from typing import Any
+
+from datadog_checks.base.utils.discovery import Service, candidate_ports
+from datadog_checks.prefect.config_models import discovery_overrides
+from datadog_checks.prefect.config_models.instance import InstanceConfig
+from datadog_checks.prefect.config_models.shared import SharedConfig
+
+
+def _generated_candidates(service: Service) -> Iterator[dict[str, Any]]:
+    shared = SharedConfig.model_validate({}, context={'configured_fields': frozenset()}).model_dump(
+        by_alias=True, mode='json', exclude_none=True
+    )
+    # discovery[0]: from_ports
+    for port in candidate_ports(service, [4200]):
+        ctx = {'port': port}
+        instance_data = {
+            'prefect_url': 'http://{service.host}:{port.number}/api'.format(service=service, **ctx),
+        }
+        instance = InstanceConfig.model_validate(
+            instance_data, context={'configured_fields': frozenset(instance_data)}
+        ).model_dump(by_alias=True, mode='json', exclude_none=True)
+        yield {'init_config': shared, 'instances': [instance]}
+
+
+def candidates(service: Service) -> Iterator[dict[str, Any]]:
+    override = getattr(discovery_overrides, 'candidates', None)
+    if override is None:
+        yield from _generated_candidates(service)
+    else:
+        yield from override(service, default=_generated_candidates)

prefect/datadog_checks/prefect/config_models/discovery_overrides.py

@@ -0,0 +1,12 @@
+# (C) Datadog, Inc. 2026-present
+# All rights reserved
+# Licensed under a 3-clause BSD style license (see LICENSE)
+
+# Override the generated discovery candidates() for this integration.
+#
+# Define a candidates(service, default) function to wrap or replace the generated
+# candidate generation. `default` is the generated generator; call it to reuse
+# the spec-driven candidates, or ignore it to replace them entirely.
+#
+# def candidates(service, default):
+#     yield from default(service)

prefect/datadog_checks/prefect/config_models/discovery_strategies.py

@@ -0,0 +1,18 @@
+# (C) Datadog, Inc. 2026-present
+# All rights reserved
+# Licensed under a 3-clause BSD style license (see LICENSE)
+
+# Here you can define custom (local:) discovery strategies for this integration.
+#
+# Decorate a generator with @discovery_strategy (imported from
+# datadog_checks.base.utils.discovery) and reference it from the spec discovery
+# stanza as `strategy: local:<function_name>`. The function receives the
+# discovered Service plus the inputs declared in the spec and yields one context
+# (ctx) mapping per candidate, exposing the keys listed in `provides`.
+#
+# from datadog_checks.base.utils.discovery import discovery_strategy
+#
+# @discovery_strategy(provides=('svc',))
+# def from_some_config(service, config_path):
+#     ...
+#     yield {'svc': ...}

prefect/datadog_checks/prefect/data/auto_conf.yaml

@@ -0,0 +1,19 @@
+## @param ad_identifiers - list of strings - required
+## A list of container identifiers that are used by Autodiscovery to identify
+## which container the check should be run against. For more information, see:
+## https://docs.datadoghq.com/agent/guide/ad_identifiers/
+#
+ad_identifiers:
+  - prefect
+
+## Enables configuration discovery
+#
+discovery: {}
+
+## Unused init configuration
+#
+init_config:
+
+## Unused instance configuration
+#
+instances: []

prefect/tests/conftest.py

@@ -10,7 +10,7 @@
 import requests
 
 from datadog_checks.dev.conditions import CheckDockerLogs, CheckEndpoints, WaitFor
-from datadog_checks.dev.docker import docker_run, get_docker_hostname
+from datadog_checks.dev.docker import docker_run, get_docker_hostname, get_e2e_discovery_metadata
 from datadog_checks.dev.utils import find_free_port
 from datadog_checks.prefect import PrefectCheck
 
@@ -65,7 +65,7 @@ def dd_environment(instance: Callable[[str], dict[str, str | dict[str, list[str]
     ):
         yield (
             {"instances": [instance(prefect_url)]},
-            E2E_METADATA,
+            {**E2E_METADATA, **get_e2e_discovery_metadata()},
         )
 
 

prefect/tests/test_e2e.py

@@ -4,7 +4,9 @@
 
 import pytest
 
+from datadog_checks.dev.docker import assert_all_discovery_candidates_stable
 from datadog_checks.dev.utils import get_metadata_metrics
+from datadog_checks.prefect import PrefectCheck
 
 WORK_POOL_TAG_KEYS = ["work_pool_id:", "work_pool_name:", "work_pool_type:"]
 
@@ -81,10 +83,7 @@
 }
 
 
-@pytest.mark.e2e
-def test_e2e_metrics(dd_agent_check):
-    aggregator = dd_agent_check(check_times=2, pause=20000)
-
+def _assert_e2e_metrics(aggregator):
     cross_check_metrics = (
         'flow_runs.retry_gaps_duration',
         'task_runs.dependency_wait_duration',
@@ -106,3 +105,20 @@ def test_e2e_metrics(dd_agent_check):
     for metric_name, expected_tags in E2E_METRIC_TAGS.items():
         for tag in expected_tags:
             aggregator.assert_metric_has_tag_prefix(metric_name, tag)
+
+
+@pytest.mark.e2e
+def test_e2e_metrics(dd_agent_check):
+    aggregator = dd_agent_check(check_times=2, pause=20000)
+    _assert_e2e_metrics(aggregator)
+
+
+@pytest.mark.e2e
+def test_e2e_discovery(dd_agent_check_discovery):
+    aggregator = dd_agent_check_discovery(check_times=2, pause=20000)
+    _assert_e2e_metrics(aggregator)
+
+
+@pytest.mark.e2e
+def test_e2e_discovery_all_candidates(dd_agent_check):
+    assert_all_discovery_candidates_stable(dd_agent_check, PrefectCheck, compose_service='prefect-server')