refactor(rustfs): move module switches below the layer boundary

backlog#1834 PR5. Whether the scanner, heal, audit and notify modules are on gets read from infra (storage helpers, node-service RPC) and from interface (admin handlers), but the switches lived in startup_background (composition) and server (interface). Every one of those reads was an upward edge carried in the layer-dependency baseline.

The env-derived scanner/heal predicates and the audit/notify state cells now live in rustfs/src/module_switches.rs, at the bottom of the layer order, so the same reads are ordinary downward edges. startup_background and server import from there; server keeps re-exporting the getters for its own consumers.

The issue's plan was to move is/refresh_audit/notify_module_enabled as a group. Moving refresh_* wholesale would have dragged resolve_audit_module_state and resolve_notify_module_state — server-side configuration logic — down into infra, which breaks more layering than it fixes. State and resolution are split instead: module_switches owns the atomics plus is_*/set_* accessors, and server's refresh_* keeps the configuration logic and publishes through the setter.

That leaves storage/helper.rs's test module importing refresh_* from server, so two infra->interface edges stay. Those tests assert that a configuration change takes effect through refresh, which a plain setter would no longer exercise; the edges are worth more than the two baseline lines.

Baseline drops 44 -> 36 lines, deletions only:

- 4 interface/infra -> composition edges for ENV_SCANNER_ENABLED, scanner_enabled_from_env and heal_enabled_from_env
- 2 infra -> interface edges for is_audit_module_enabled and is_notify_module_enabled
- cycle|composition<->infra and cycle|composition<->interface

The two cycles were not expected to go until whole subsystems moved out; clearing composition's inbound upward edges dissolved both, leaving three of the original five.

Verification: scripts/check_layer_dependencies.sh passes, cargo check -p rustfs warning-free, make pre-commit exit 0.

rustfs/src/admin/handlers/scanner.rs

@@ -16,8 +16,8 @@ use crate::admin::auth::validate_admin_request;
 use crate::admin::router::{AdminOperation, Operation, S3Router};
 use crate::admin::runtime_sources::current_scanner_metrics_report;
 use crate::auth::{check_key_valid, get_session_token};
+use crate::module_switches::{ENV_SCANNER_ENABLED, scanner_enabled_from_env};
 use crate::server::{ADMIN_PREFIX, RemoteAddr};
-use crate::startup_background::{ENV_SCANNER_ENABLED, scanner_enabled_from_env};
 use chrono::Utc;
 use http::{HeaderMap, HeaderValue};
 use hyper::{Method, StatusCode};

rustfs/src/lib.rs

@@ -88,6 +88,7 @@ pub mod inspect;
 pub(crate) mod kms_deletion_gate;
 pub mod license;
 pub mod memory_observability;
+pub mod module_switches;
 pub mod profiling;
 #[cfg(any(feature = "ftps", feature = "webdav", feature = "sftp"))]
 pub mod protocols;

rustfs/src/module_switches.rs

@@ -0,0 +1,68 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Layer-neutral module switches (backlog#1834).
+//!
+//! Whether the scanner, heal, audit and notify modules are on is read from the
+//! infra layer (storage helpers, node-service RPC) and from the interface layer
+//! (admin handlers), but the switches used to live in `startup_background`
+//! (composition) and `server` (interface). Every lower-layer read was therefore
+//! an upward edge that had to be baselined by the layer-dependency guard.
+//!
+//! The env-derived scanner/heal predicates and the audit/notify state cells now
+//! live here, at the bottom of the layer order, so those reads are ordinary
+//! downward edges. Resolving the audit/notify state still needs server-side
+//! configuration, so `server::refresh_audit_module_enabled` and its notify twin
+//! keep that logic and publish the result through the setters below.
+
+use rustfs_utils::get_env_bool_with_aliases;
+use std::sync::atomic::{AtomicBool, Ordering};
+
+pub(crate) const ENV_SCANNER_ENABLED: &str = "RUSTFS_SCANNER_ENABLED";
+pub(crate) const ENV_SCANNER_ENABLED_DEPRECATED: &str = "RUSTFS_ENABLE_SCANNER";
+pub(crate) const ENV_HEAL_ENABLED: &str = "RUSTFS_HEAL_ENABLED";
+pub(crate) const ENV_HEAL_ENABLED_DEPRECATED: &str = "RUSTFS_ENABLE_HEAL";
+
+static AUDIT_MODULE_ENABLED: AtomicBool = AtomicBool::new(rustfs_config::DEFAULT_AUDIT_ENABLE);
+static NOTIFY_MODULE_ENABLED: AtomicBool = AtomicBool::new(rustfs_config::DEFAULT_NOTIFY_ENABLE);
+
+/// Whether the data scanner is enabled, defaulting to on.
+pub(crate) fn scanner_enabled_from_env() -> bool {
+    get_env_bool_with_aliases(ENV_SCANNER_ENABLED, &[ENV_SCANNER_ENABLED_DEPRECATED], true)
+}
+
+/// Whether background heal is enabled, defaulting to on.
+pub(crate) fn heal_enabled_from_env() -> bool {
+    get_env_bool_with_aliases(ENV_HEAL_ENABLED, &[ENV_HEAL_ENABLED_DEPRECATED], true)
+}
+
+/// Last published audit-module state.
+pub fn is_audit_module_enabled() -> bool {
+    AUDIT_MODULE_ENABLED.load(Ordering::Relaxed)
+}
+
+/// Publish the audit-module state resolved by `server::refresh_audit_module_enabled`.
+pub(crate) fn set_audit_module_enabled(enabled: bool) {
+    AUDIT_MODULE_ENABLED.store(enabled, Ordering::Relaxed);
+}
+
+/// Last published notify-module state.
+pub fn is_notify_module_enabled() -> bool {
+    NOTIFY_MODULE_ENABLED.load(Ordering::Relaxed)
+}
+
+/// Publish the notify-module state resolved by `server::refresh_notify_module_enabled`.
+pub(crate) fn set_notify_module_enabled(enabled: bool) {
+    NOTIFY_MODULE_ENABLED.store(enabled, Ordering::Relaxed);
+}

rustfs/src/server/audit.rs

@@ -19,11 +19,8 @@ use super::{
 use crate::runtime_sources::AppContext;
 use rustfs_audit::{AuditError, AuditResult, audit_system, init_audit_system, system::AuditSystemState};
 use std::collections::HashSet;
-use std::sync::atomic::{AtomicBool, Ordering};
 use tracing::{info, warn};
 
-static AUDIT_MODULE_ENABLED: AtomicBool = AtomicBool::new(rustfs_config::DEFAULT_AUDIT_ENABLE);
-
 fn server_config_from_context() -> Option<rustfs_config::server_config::Config> {
     runtime_sources::current_server_config()
 }
@@ -37,13 +34,11 @@ fn server_config_for_context(context: Option<&AppContext>) -> Option<rustfs_conf
 
 pub fn refresh_audit_module_enabled() -> bool {
     let enabled = resolve_audit_module_state().enabled;
-    AUDIT_MODULE_ENABLED.store(enabled, Ordering::Relaxed);
+    crate::module_switches::set_audit_module_enabled(enabled);
     enabled
 }
 
-pub fn is_audit_module_enabled() -> bool {
-    AUDIT_MODULE_ENABLED.load(Ordering::Relaxed)
-}
+pub use crate::module_switches::is_audit_module_enabled;
 
 fn has_any_persisted_audit_targets(config: &rustfs_config::server_config::Config) -> bool {
     for &subsystem in rustfs_config::audit::AUDIT_SUB_SYSTEMS {

rustfs/src/server/event.rs

@@ -34,7 +34,6 @@ use tokio::time::{Instant, MissedTickBehavior};
 use tokio_util::sync::CancellationToken;
 use tracing::{info, instrument, warn};
 
-static NOTIFY_MODULE_ENABLED: AtomicBool = AtomicBool::new(rustfs_config::DEFAULT_NOTIFY_ENABLE);
 static NOTIFY_RUNTIME_RECONCILED: AtomicBool = AtomicBool::new(false);
 static NOTIFY_BUCKET_RULES_RECONCILED: AtomicBool = AtomicBool::new(false);
 static ECSTORE_EVENT_DISPATCH_HOOK: OnceLock<()> = OnceLock::new();
@@ -70,13 +69,11 @@ fn should_reconcile_bucket_notification_rules(runtime_changed: bool, notify_enab
 
 pub fn refresh_notify_module_enabled() -> bool {
     let enabled = resolve_notify_module_state().enabled;
-    NOTIFY_MODULE_ENABLED.store(enabled, Ordering::Relaxed);
+    crate::module_switches::set_notify_module_enabled(enabled);
     enabled
 }
 
-pub fn is_notify_module_enabled() -> bool {
-    NOTIFY_MODULE_ENABLED.load(Ordering::Relaxed)
-}
+pub use crate::module_switches::is_notify_module_enabled;
 
 pub(crate) use crate::shared_types::convert_ecstore_object_info;
 
@@ -171,7 +168,7 @@ pub(crate) async fn reconcile_event_notifier_from_store(
         let transition_system = system.clone();
         let transition_store = store.clone();
         let transition = with_refreshed_notify_module_state_from(store.clone(), move |resolution| async move {
-            NOTIFY_MODULE_ENABLED.store(resolution.enabled, Ordering::Relaxed);
+            crate::module_switches::set_notify_module_enabled(resolution.enabled);
             let read_store = transition_store.clone();
             let config_system = transition_system.clone();
             with_server_config_read_lock(transition_store, move || async move {

rustfs/src/startup_background.rs

@@ -12,32 +12,20 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use crate::module_switches::{heal_enabled_from_env, scanner_enabled_from_env};
 use crate::storage_api::startup::background::{ECStore, set_workload_admission_snapshot_provider};
 use crate::workload_admission::RustFsWorkloadAdmissionSnapshotProvider;
 use rustfs_concurrency::WorkloadAdmissionSnapshotProvider;
 use rustfs_heal::{
     create_ahm_services_cancel_token, heal::storage::ECStoreHealStorage, init_heal_manager_with_workload_provider,
 };
-use rustfs_utils::get_env_bool_with_aliases;
 use std::{io::Result, sync::Arc};
 use tracing::{debug, info};
 
-pub(crate) const ENV_SCANNER_ENABLED: &str = "RUSTFS_SCANNER_ENABLED";
-pub(crate) const ENV_SCANNER_ENABLED_DEPRECATED: &str = "RUSTFS_ENABLE_SCANNER";
-pub(crate) const ENV_HEAL_ENABLED: &str = "RUSTFS_HEAL_ENABLED";
-pub(crate) const ENV_HEAL_ENABLED_DEPRECATED: &str = "RUSTFS_ENABLE_HEAL";
 const LOG_COMPONENT_MAIN: &str = "main";
 const LOG_SUBSYSTEM_STARTUP: &str = "startup";
 const EVENT_BACKGROUND_SERVICES_CONFIGURED: &str = "background_services_configured";
 
-pub(crate) fn scanner_enabled_from_env() -> bool {
-    get_env_bool_with_aliases(ENV_SCANNER_ENABLED, &[ENV_SCANNER_ENABLED_DEPRECATED], true)
-}
-
-pub(crate) fn heal_enabled_from_env() -> bool {
-    get_env_bool_with_aliases(ENV_HEAL_ENABLED, &[ENV_HEAL_ENABLED_DEPRECATED], true)
-}
-
 pub(crate) async fn init_background_service_runtime(store: Arc<ECStore>) -> Result<bool> {
     let _ = create_ahm_services_cancel_token();
 

rustfs/src/storage/helper.rs

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use crate::server::{is_audit_module_enabled, is_notify_module_enabled};
+use crate::module_switches::{is_audit_module_enabled, is_notify_module_enabled};
 use crate::shared_types::convert_ecstore_object_info;
 use crate::storage::access::{ReqInfo, request_context_from_req};
 use crate::storage::request_context::RequestContext;

rustfs/src/storage/rpc/node_service/heal.rs

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use crate::startup_background::{heal_enabled_from_env, scanner_enabled_from_env};
+use crate::module_switches::{heal_enabled_from_env, scanner_enabled_from_env};
 use crate::storage::storage_api::runtime_sources_consumer::EndpointServerPools;
 use jiff::Timestamp;
 use rmp_serde::Deserializer;

scripts/layer-dependency-baseline.txt

@@ -16,11 +16,7 @@
 #   cycle|left_layer<->right_layer
 cycle|app<->infra
 cycle|app<->interface
-cycle|composition<->infra
-cycle|composition<->interface
 cycle|infra<->interface
-dep|rustfs/src/admin/handlers/scanner.rs|interface->composition|crate::startup_background::ENV_SCANNER_ENABLED
-dep|rustfs/src/admin/handlers/scanner.rs|interface->composition|crate::startup_background::scanner_enabled_from_env
 dep|rustfs/src/app/admin_usecase.rs|app->interface|crate::server::collect_dependency_readiness_report
 dep|rustfs/src/app/bucket_usecase.rs|app->interface|crate::admin::handlers::site_replication::site_replication_bucket_meta_hook
 dep|rustfs/src/app/bucket_usecase.rs|app->interface|crate::admin::handlers::site_replication::site_replication_delete_bucket_hook
@@ -29,8 +25,6 @@ dep|rustfs/src/cluster_snapshot.rs|infra->interface|crate::server::snapshot_depe
 dep|rustfs/src/runtime_sources.rs|infra->app|crate::app::context
 dep|rustfs/src/storage/ecfs_extend.rs|infra->interface|crate::server::cors
 dep|rustfs/src/storage/ecfs_extend.rs|infra->interface|crate::storage::ecfs::ListObjectUnorderedQuery
-dep|rustfs/src/storage/helper.rs|infra->interface|crate::server::is_audit_module_enabled
-dep|rustfs/src/storage/helper.rs|infra->interface|crate::server::is_notify_module_enabled
 dep|rustfs/src/storage/helper.rs|infra->interface|crate::server::refresh_audit_module_enabled
 dep|rustfs/src/storage/helper.rs|infra->interface|crate::server::refresh_notify_module_enabled
 dep|rustfs/src/storage/rpc/http_service.rs|infra->interface|crate::server::RPC_PREFIX
@@ -40,5 +34,3 @@ dep|rustfs/src/storage/rpc/node_service.rs|infra->interface|crate::admin::servic
 dep|rustfs/src/storage/rpc/node_service.rs|infra->interface|crate::admin::service::config::reload_runtime_config_snapshot
 dep|rustfs/src/storage/rpc/node_service.rs|infra->interface|crate::admin::service::site_replication::reload_site_replication_runtime_state
 dep|rustfs/src/storage/rpc/node_service.rs|infra->interface|crate::server::MODULE_SWITCHES_SIGNAL_SUBSYSTEM
-dep|rustfs/src/storage/rpc/node_service/heal.rs|infra->composition|crate::startup_background::heal_enabled_from_env
-dep|rustfs/src/storage/rpc/node_service/heal.rs|infra->composition|crate::startup_background::scanner_enabled_from_env