[core] custom checks location have lower precedence than wheels, bund…

…led checks (#1087)

cmd/agent/common/common.go

@@ -44,9 +44,9 @@ var (
 func GetPythonPaths() []string {
 	return []string{
 		GetDistPath(),                                  // common modules are shipped in the dist path directly or under the "checks/" sub-dir
-		filepath.Join(GetDistPath(), "checks.d"),       // custom checks in the "checks.d/" sub-dir of the dist path
-		config.Datadog.GetString("additional_checksd"), // custom checks, have precedence over integrations-core checks
 		PySitePackages,                                 // integrations-core, wheels have precedence over old-school SDK
 		PyChecksPath,                                   // integrations-core checks
+		filepath.Join(GetDistPath(), "checks.d"),       // custom checks in the "checks.d/" sub-dir of the dist path
+		config.Datadog.GetString("additional_checksd"), // custom checks, least precedent check location
 	}
 }

releasenotes/notes/checks-loading-precedence-change-472c65d1af6e6739.yaml

@@ -0,0 +1,8 @@
+---
+upgrade:
+  - |
+    Custom checks (located by default on Linux in ``/etc/datadog-agent/checks.d/``) now have a
+    *lower* precedence than the checks that are bundled with the Agent. This means that a custom
+    check with the same name as a bundled check will now be ignored, and the bundled check will be
+    loaded instead. If you want to override a bundled check with a custom check, please use a
+    new name for your custom check, and use that new name for the related yaml configuration file.