Feature: Allow to load a core plugin as external (#75157)

pkg/services/pluginsintegration/pipeline/steps.go

@@ -157,3 +157,61 @@ func (c *DisablePlugins) Filter(bundles []*plugins.FoundBundle) ([]*plugins.Foun
 	}
 	return res, nil
 }
+
+// AsExternal is a filter step that will skip loading a core plugin to use an external one.
+type AsExternal struct {
+	log log.Logger
+	cfg *config.Cfg
+}
+
+// NewDisablePluginsStep returns a new DisablePlugins.
+func NewAsExternalStep(cfg *config.Cfg) *AsExternal {
+	return &AsExternal{
+		cfg: cfg,
+		log: log.New("plugins.asExternal"),
+	}
+}
+
+// Filter will filter out any plugins that are marked to be disabled.
+func (c *AsExternal) Filter(cl plugins.Class, bundles []*plugins.FoundBundle) ([]*plugins.FoundBundle, error) {
+	if c.cfg.Features == nil || !c.cfg.Features.IsEnabled(featuremgmt.FlagExternalCorePlugins) {
+		return bundles, nil
+	}
+
+	if cl == plugins.ClassCore {
+		res := []*plugins.FoundBundle{}
+		for _, bundle := range bundles {
+			pluginCfg := c.cfg.PluginSettings[bundle.Primary.JSONData.ID]
+			// Skip core plugins if the feature flag is enabled and the plugin is in the skip list.
+			// It could be loaded later as an external plugin.
+			if pluginCfg["as_external"] == "true" {
+				c.log.Debug("Skipping the core plugin load", "pluginID", bundle.Primary.JSONData.ID)
+			} else {
+				res = append(res, bundle)
+			}
+		}
+		return res, nil
+	}
+
+	if cl == plugins.ClassExternal {
+		// Warn if the plugin is not found in the external plugins directory.
+		asExternal := map[string]bool{}
+		for pluginID, pluginCfg := range c.cfg.PluginSettings {
+			if pluginCfg["as_external"] == "true" {
+				asExternal[pluginID] = true
+			}
+		}
+		for _, bundle := range bundles {
+			if asExternal[bundle.Primary.JSONData.ID] {
+				delete(asExternal, bundle.Primary.JSONData.ID)
+			}
+		}
+		if len(asExternal) > 0 {
+			for p := range asExternal {
+				c.log.Error("Core plugin expected to be loaded as external, but it is missing", "pluginID", p)
+			}
+		}
+	}
+
+	return bundles, nil
+}