From 7287a86d283489127453009267911003cea5227e Mon Sep 17 00:00:00 2001
From: Ainar Garipov <A.Garipov@AdGuard.COM>
Date: Fri, 7 Oct 2022 13:39:44 +0300
Subject: [PATCH] WIP all: impl dynamic reconfiguration

---
 internal/aghos/filewalker_internal_test.go |   6 +-
 internal/aghos/os.go                       |  10 +
 internal/aghos/os_unix.go                  |   8 +
 internal/aghos/os_windows.go               |   8 +
 internal/aghtest/interface.go              |  17 +-
 internal/aghtest/interface_test.go         |   8 +-
 internal/next/agh/agh.go                   |  40 +++-
 internal/next/cmd/cmd.go                   |  33 ++--
 internal/next/cmd/signal.go                |  48 ++++-
 internal/next/svc/config.go                |  40 ++++
 internal/next/svc/configmanager.go         | 202 +++++++++++++++++++++
 internal/next/svc/svc.go                   |   3 +
 internal/next/websvc/dns_test.go           |   3 +-
 internal/next/websvc/http.go               |   3 +-
 internal/next/websvc/http_test.go          |   3 +-
 internal/next/websvc/settings_test.go      |   5 +-
 internal/next/websvc/websvc.go             |  15 +-
 internal/next/websvc/websvc_test.go        |  13 +-
 scripts/make/go-build.sh                   |   4 +-
 19 files changed, 402 insertions(+), 67 deletions(-)
 create mode 100644 internal/next/svc/config.go
 create mode 100644 internal/next/svc/configmanager.go
 create mode 100644 internal/next/svc/svc.go

diff --git a/internal/aghos/filewalker_internal_test.go b/internal/aghos/filewalker_internal_test.go
index bb162812fdb..732afc9bac2 100644
--- a/internal/aghos/filewalker_internal_test.go
+++ b/internal/aghos/filewalker_internal_test.go
@@ -15,11 +15,11 @@ import (
 // errFSOpen.
 type errFS struct{}
 
-// errFSOpen is returned from errGlobFS.Open.
+// errFSOpen is returned from errFS.Open.
 const errFSOpen errors.Error = "test open error"
 
-// Open implements the fs.FS interface for *errGlobFS.  fsys is always nil and
-// err is always errFSOpen.
+// Open implements the fs.FS interface for *errFS.  fsys is always nil and err
+// is always errFSOpen.
 func (efs *errFS) Open(name string) (fsys fs.File, err error) {
 	return nil, errFSOpen
 }
diff --git a/internal/aghos/os.go b/internal/aghos/os.go
index b39ecbbd857..26201df2277 100644
--- a/internal/aghos/os.go
+++ b/internal/aghos/os.go
@@ -175,11 +175,21 @@ func RootDirFS() (fsys fs.FS) {
 	return os.DirFS("")
 }
 
+// NotifyReconfigureSignal notifies c on receiving reconfigure signals.
+func NotifyReconfigureSignal(c chan<- os.Signal) {
+	notifyReconfigureSignal(c)
+}
+
 // NotifyShutdownSignal notifies c on receiving shutdown signals.
 func NotifyShutdownSignal(c chan<- os.Signal) {
 	notifyShutdownSignal(c)
 }
 
+// IsReconfigureSignal returns true if sig is a reconfigure signal.
+func IsReconfigureSignal(sig os.Signal) (ok bool) {
+	return isReconfigureSignal(sig)
+}
+
 // IsShutdownSignal returns true if sig is a shutdown signal.
 func IsShutdownSignal(sig os.Signal) (ok bool) {
 	return isShutdownSignal(sig)
diff --git a/internal/aghos/os_unix.go b/internal/aghos/os_unix.go
index da8ee912d8c..7e04f0c0c82 100644
--- a/internal/aghos/os_unix.go
+++ b/internal/aghos/os_unix.go
@@ -9,10 +9,18 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+func notifyReconfigureSignal(c chan<- os.Signal) {
+	signal.Notify(c, unix.SIGHUP)
+}
+
 func notifyShutdownSignal(c chan<- os.Signal) {
 	signal.Notify(c, unix.SIGINT, unix.SIGQUIT, unix.SIGTERM)
 }
 
+func isReconfigureSignal(sig os.Signal) (ok bool) {
+	return sig == unix.SIGHUP
+}
+
 func isShutdownSignal(sig os.Signal) (ok bool) {
 	switch sig {
 	case
diff --git a/internal/aghos/os_windows.go b/internal/aghos/os_windows.go
index c79a603fd8c..d22c1fdd4db 100644
--- a/internal/aghos/os_windows.go
+++ b/internal/aghos/os_windows.go
@@ -39,12 +39,20 @@ func isOpenWrt() (ok bool) {
 	return false
 }
 
+func notifyReconfigureSignal(c chan<- os.Signal) {
+	signal.Notify(c, windows.SIGHUP)
+}
+
 func notifyShutdownSignal(c chan<- os.Signal) {
 	// syscall.SIGTERM is processed automatically.  See go doc os/signal,
 	// section Windows.
 	signal.Notify(c, os.Interrupt)
 }
 
+func isReconfigureSignal(sig os.Signal) (ok bool) {
+	return sig == windows.SIGHUP
+}
+
 func isShutdownSignal(sig os.Signal) (ok bool) {
 	switch sig {
 	case
diff --git a/internal/aghtest/interface.go b/internal/aghtest/interface.go
index 7aae35ee3ee..ea91988904b 100644
--- a/internal/aghtest/interface.go
+++ b/internal/aghtest/interface.go
@@ -6,6 +6,7 @@ import (
 	"net"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghos"
+	"github.com/AdguardTeam/AdGuardHome/internal/next/agh"
 	"github.com/AdguardTeam/dnsproxy/upstream"
 	"github.com/miekg/dns"
 )
@@ -88,7 +89,7 @@ func (l *Listener) Close() (err error) {
 	return l.OnClose()
 }
 
-// Module AdGuardHome
+// Module adguard-home
 
 // Package aghos
 
@@ -117,29 +118,31 @@ func (w *FSWatcher) Close() (err error) {
 	return w.OnClose()
 }
 
-// Package websvc
+// Package agh
 
-// ServiceWithConfig is a mock [websvc.ServiceWithConfig] implementation for
-// tests.
+// type check
+var _ agh.ServiceWithConfig[struct{}] = (*ServiceWithConfig[struct{}])(nil)
+
+// ServiceWithConfig is a mock [agh.ServiceWithConfig] implementation for tests.
 type ServiceWithConfig[ConfigType any] struct {
 	OnStart    func() (err error)
 	OnShutdown func(ctx context.Context) (err error)
 	OnConfig   func() (c ConfigType)
 }
 
-// Start implements the [websvc.ServiceWithConfig] interface for
+// Start implements the [agh.ServiceWithConfig] interface for
 // *ServiceWithConfig.
 func (s *ServiceWithConfig[_]) Start() (err error) {
 	return s.OnStart()
 }
 
-// Shutdown implements the [websvc.ServiceWithConfig] interface for
+// Shutdown implements the [agh.ServiceWithConfig] interface for
 // *ServiceWithConfig.
 func (s *ServiceWithConfig[_]) Shutdown(ctx context.Context) (err error) {
 	return s.OnShutdown(ctx)
 }
 
-// Config implements the [websvc.ServiceWithConfig] interface for
+// Config implements the [agh.ServiceWithConfig] interface for
 // *ServiceWithConfig.
 func (s *ServiceWithConfig[ConfigType]) Config() (c ConfigType) {
 	return s.OnConfig()
diff --git a/internal/aghtest/interface_test.go b/internal/aghtest/interface_test.go
index bd2c0823e84..9141d132c54 100644
--- a/internal/aghtest/interface_test.go
+++ b/internal/aghtest/interface_test.go
@@ -1,9 +1,3 @@
 package aghtest_test
 
-import (
-	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
-	"github.com/AdguardTeam/AdGuardHome/internal/next/websvc"
-)
-
-// type check
-var _ websvc.ServiceWithConfig[struct{}] = (*aghtest.ServiceWithConfig[struct{}])(nil)
+// Put interface checks that cause import cycles here.
diff --git a/internal/next/agh/agh.go b/internal/next/agh/agh.go
index 212da4d685b..c70207f1d0c 100644
--- a/internal/next/agh/agh.go
+++ b/internal/next/agh/agh.go
@@ -1,6 +1,4 @@
 // Package agh contains common entities and interfaces of AdGuard Home.
-//
-// TODO(a.garipov): Move to the upper-level internal/.
 package agh
 
 import "context"
@@ -23,11 +21,43 @@ type Service interface {
 // type check
 var _ Service = EmptyService{}
 
-// EmptyService is a Service that does nothing.
+// EmptyService is a [Service] that does nothing.
+//
+// TODO(a.garipov): Remove if unnecessary.
 type EmptyService struct{}
 
-// Start implements the Service interface for EmptyService.
+// Start implements the [Service] interface for EmptyService.
 func (EmptyService) Start() (err error) { return nil }
 
-// Shutdown implements the Service interface for EmptyService.
+// Shutdown implements the [Service] interface for EmptyService.
 func (EmptyService) Shutdown(_ context.Context) (err error) { return nil }
+
+// ServiceWithConfig is an extension of the [Service] interface for services
+// that can return their configuration.
+//
+// TODO(a.garipov): Consider removing this generic interface if we figure out
+// how to make it testable in a better way.
+type ServiceWithConfig[ConfigType any] interface {
+	Service
+
+	Config() (c ConfigType)
+}
+
+// type check
+var _ ServiceWithConfig[struct{}] = (*EmptyServiceWithConfig[struct{}])(nil)
+
+// EmptyServiceWithConfig is a ServiceWithConfig that does nothing.  Its Config
+// method returns Conf.
+//
+// TODO(a.garipov): Remove if unnecessary.
+type EmptyServiceWithConfig[T any] struct {
+	EmptyService
+
+	Conf T
+}
+
+// Config implements the [ServiceWithConfig] interface for
+// *EmptyServiceWithConfig.
+func (s *EmptyServiceWithConfig[ConfigType]) Config() (conf ConfigType) {
+	return s.Conf
+}
diff --git a/internal/next/cmd/cmd.go b/internal/next/cmd/cmd.go
index 5b329abf4a6..1d526afc172 100644
--- a/internal/next/cmd/cmd.go
+++ b/internal/next/cmd/cmd.go
@@ -8,10 +8,11 @@ import (
 	"context"
 	"io/fs"
 	"math/rand"
-	"net/netip"
+	"os"
 	"time"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/next/websvc"
+	"github.com/AdguardTeam/AdGuardHome/internal/next/svc"
+	"github.com/AdguardTeam/AdGuardHome/internal/version"
 	"github.com/AdguardTeam/golibs/log"
 )
 
@@ -24,29 +25,33 @@ func Main(clientBuildFS fs.FS) {
 
 	// TODO(a.garipov): Set up logging.
 
+	log.Info("starting adguard home, version %s, pid %d", version.Version(), os.Getpid())
+
 	// Web Service
 
 	// TODO(a.garipov): Use in the Web service.
 	_ = clientBuildFS
 
-	// TODO(a.garipov): Make configurable.
-	web := websvc.New(&websvc.Config{
-		// TODO(a.garipov): Use an actual implementation.
-		ConfigManager: nil,
-		Addresses:     []netip.AddrPort{netip.MustParseAddrPort("127.0.0.1:3001")},
-		Start:         start,
-		Timeout:       60 * time.Second,
-		ForceHTTPS:    false,
-	})
-
-	err := web.Start()
+	// TODO(a.garipov): Set up configuration file name.
+	const confFile = "AdGuardHome.1.yaml"
+
+	confMgr, err := svc.New(confFile, start)
+	fatalOnError(err)
+
+	web := confMgr.Web()
+	err = web.Start()
+	fatalOnError(err)
+
+	dns := confMgr.DNS()
+	err = dns.Start()
 	fatalOnError(err)
 
 	sigHdlr := newSignalHandler(
 		web,
+		dns,
 	)
 
-	go sigHdlr.handle()
+	go sigHdlr.handle(confFile, start)
 
 	select {}
 }
diff --git a/internal/next/cmd/signal.go b/internal/next/cmd/signal.go
index 122f3f2c7dd..5ae35d4f37c 100644
--- a/internal/next/cmd/signal.go
+++ b/internal/next/cmd/signal.go
@@ -2,9 +2,11 @@ package cmd
 
 import (
 	"os"
+	"time"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghos"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/agh"
+	"github.com/AdguardTeam/AdGuardHome/internal/next/svc"
 	"github.com/AdguardTeam/golibs/log"
 )
 
@@ -18,18 +20,49 @@ type signalHandler struct {
 }
 
 // handle processes OS signals.
-func (h *signalHandler) handle() {
+func (h *signalHandler) handle(confFile string, start time.Time) {
 	defer log.OnPanic("signalHandler.handle")
 
 	for sig := range h.signal {
 		log.Info("sighdlr: received signal %q", sig)
 
-		if aghos.IsShutdownSignal(sig) {
-			h.shutdown()
+		if aghos.IsReconfigureSignal(sig) {
+			h.reconfigure(confFile, start)
+		} else if aghos.IsShutdownSignal(sig) {
+			h.shutdown(true)
 		}
 	}
 }
 
+// reconfigure rereads the configuration file and updates and restarts services.
+func (h *signalHandler) reconfigure(confFile string, start time.Time) {
+	log.Info("sighdlr: reconfiguring adguard home")
+
+	h.shutdown(false)
+
+	// TODO(a.garipov): This is a very rough way to do it.  Some services can be
+	// reconfigured without the full shutdown, and the error handling is
+	// currently not the best.
+
+	confMgr, err := svc.New(confFile, start)
+	fatalOnError(err)
+
+	web := confMgr.Web()
+	err = web.Start()
+	fatalOnError(err)
+
+	dns := confMgr.DNS()
+	err = dns.Start()
+	fatalOnError(err)
+
+	h.services = []agh.Service{
+		dns,
+		web,
+	}
+
+	log.Info("sighdlr: successfully reconfigured adguard home")
+}
+
 // Exit status constants.
 const (
 	statusSuccess = 0
@@ -37,7 +70,7 @@ const (
 )
 
 // shutdown gracefully shuts down all services.
-func (h *signalHandler) shutdown() {
+func (h *signalHandler) shutdown(shouldExit bool) {
 	ctx, cancel := ctxWithDefaultTimeout()
 	defer cancel()
 
@@ -54,7 +87,11 @@ func (h *signalHandler) shutdown() {
 
 	log.Info("sighdlr: shutting down adguard home")
 
-	os.Exit(status)
+	if shouldExit {
+		log.Info("sighdlr: exiting with status %d", status)
+
+		os.Exit(status)
+	}
 }
 
 // newSignalHandler returns a new signalHandler that shuts down svcs.
@@ -65,6 +102,7 @@ func newSignalHandler(svcs ...agh.Service) (h *signalHandler) {
 	}
 
 	aghos.NotifyShutdownSignal(h.signal)
+	aghos.NotifyReconfigureSignal(h.signal)
 
 	return h
 }
diff --git a/internal/next/svc/config.go b/internal/next/svc/config.go
new file mode 100644
index 00000000000..480995aba02
--- /dev/null
+++ b/internal/next/svc/config.go
@@ -0,0 +1,40 @@
+package svc
+
+import (
+	"net/netip"
+
+	"github.com/AdguardTeam/golibs/timeutil"
+)
+
+// Configuration Structures
+
+// config is the top-level on-disk configuration structure.
+type config struct {
+	DNS  *dnsConfig  `yaml:"dns"`
+	HTTP *httpConfig `yaml:"http"`
+	// TODO(a.garipov): Use.
+	SchemaVersion int `yaml:"schema_version"`
+	// TODO(a.garipov): Use.
+	DebugPprof bool `yaml:"debug_pprof"`
+	Verbose    bool `yaml:"verbose"`
+}
+
+// dnsConfig is the on-disk DNS configuration.
+//
+// TODO(a.garipov): Validate.
+type dnsConfig struct {
+	Addresses       []netip.AddrPort  `yaml:"addresses"`
+	BootstrapDNS    []string          `yaml:"bootstrap_dns"`
+	UpstreamDNS     []string          `yaml:"upstream_dns"`
+	UpstreamTimeout timeutil.Duration `yaml:"upstream_timeout"`
+}
+
+// httpConfig is the on-disk web API configuration.
+//
+// TODO(a.garipov): Validate.
+type httpConfig struct {
+	Addresses       []netip.AddrPort  `yaml:"addresses"`
+	SecureAddresses []netip.AddrPort  `yaml:"secure_addresses"`
+	Timeout         timeutil.Duration `yaml:"timeout"`
+	ForceHTTPS      bool              `yaml:"force_https"`
+}
diff --git a/internal/next/svc/configmanager.go b/internal/next/svc/configmanager.go
new file mode 100644
index 00000000000..bad74e8e799
--- /dev/null
+++ b/internal/next/svc/configmanager.go
@@ -0,0 +1,202 @@
+package svc
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"sync"
+	"time"
+
+	"github.com/AdguardTeam/AdGuardHome/internal/next/agh"
+	"github.com/AdguardTeam/AdGuardHome/internal/next/dnssvc"
+	"github.com/AdguardTeam/AdGuardHome/internal/next/websvc"
+	"github.com/AdguardTeam/golibs/errors"
+	"github.com/AdguardTeam/golibs/log"
+	"gopkg.in/yaml.v3"
+)
+
+// Configuration Manager
+
+// ConfigManager handles full and partial changes in the configuration,
+// persisting them to disk if necessary.
+type ConfigManager struct {
+	// updMu makes sure that at most one reconfiguration is performed at a time.
+	// updMu protects all fields below.
+	updMu *sync.RWMutex
+
+	// dns is the DNS service.
+	dns *dnssvc.Service
+
+	// Web is the Web API service.
+	web *websvc.Service
+
+	// current is the current configuration.
+	current *config
+
+	// fileName is the name of the configuration file.
+	fileName string
+}
+
+// New creates a new ConfigManager that persists changes to the file pointed to
+// by fileName.  It reads the configuration file and populates the service
+// fields.  start is the startup time of AdGuard Home.
+func New(fileName string, start time.Time) (m *ConfigManager, err error) {
+	defer func() { err = errors.Annotate(err, "reading config") }()
+
+	conf := &config{}
+	f, err := os.Open(fileName)
+	if err != nil {
+		// Don't wrap the error, because it's informative enough as is.
+		return nil, err
+	}
+	defer func() { err = errors.WithDeferred(err, f.Close()) }()
+
+	err = yaml.NewDecoder(f).Decode(conf)
+	if err != nil {
+		// Don't wrap the error, because it's informative enough as is.
+		return nil, err
+	}
+
+	// TODO(a.garipov): Move into a separate function and add other logging
+	// settings.
+	if conf.Verbose {
+		log.SetLevel(log.DEBUG)
+	}
+
+	// TODO(a.garipov): Validate the configuration structure.  Return an error
+	// if it's incorrect.
+
+	m = &ConfigManager{
+		updMu:    &sync.RWMutex{},
+		current:  conf,
+		fileName: fileName,
+	}
+
+	// TODO(a.garipov): Get the context from the arguments?
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	err = m.assemble(ctx, conf, start)
+	if err != nil {
+		// Don't wrap the error, because it's informative enough as is.
+		return nil, err
+	}
+
+	return m, nil
+}
+
+// assemble creates all services and puts them into the corresponding fields.
+// The fields of conf must not be modified after calling assemble.
+func (m *ConfigManager) assemble(ctx context.Context, conf *config, start time.Time) (err error) {
+	dnsConf := &dnssvc.Config{
+		Addresses:        conf.DNS.Addresses,
+		BootstrapServers: conf.DNS.BootstrapDNS,
+		UpstreamServers:  conf.DNS.UpstreamDNS,
+		UpstreamTimeout:  conf.DNS.UpstreamTimeout.Duration,
+	}
+	err = m.updateDNS(ctx, dnsConf)
+	if err != nil {
+		return fmt.Errorf("assembling dnssvc: %w", err)
+	}
+
+	webSvcConf := &websvc.Config{
+		ConfigManager: m,
+		// TODO(a.garipov): this.
+		TLS:             nil,
+		Start:           start,
+		Addresses:       conf.HTTP.Addresses,
+		SecureAddresses: conf.HTTP.SecureAddresses,
+		Timeout:         conf.HTTP.Timeout.Duration,
+		ForceHTTPS:      conf.HTTP.ForceHTTPS,
+	}
+
+	err = m.updateWeb(ctx, webSvcConf)
+	if err != nil {
+		return fmt.Errorf("assembling websvc: %w", err)
+	}
+
+	return nil
+}
+
+// DNS returns the current DNS service.  It is safe for concurrent use.
+func (m *ConfigManager) DNS() (dns agh.ServiceWithConfig[*dnssvc.Config]) {
+	m.updMu.RLock()
+	defer m.updMu.RUnlock()
+
+	return m.dns
+}
+
+// UpdateDNS implements the websvc.ConfigManager interface for *ConfigManager.
+// The fields of c must not be modified after calling UpdateDNS.
+func (m *ConfigManager) UpdateDNS(ctx context.Context, c *dnssvc.Config) (err error) {
+	m.updMu.Lock()
+	defer m.updMu.Unlock()
+
+	// TODO(a.garipov): Update and write the configuration file.  Return an
+	// error if something went wrong.
+
+	err = m.updateDNS(ctx, c)
+	if err != nil {
+		return fmt.Errorf("reassembling dnssvc: %w", err)
+	}
+
+	return nil
+}
+
+// updateDNS recreates the DNS service.  m.updMu is expected to be locked.
+func (m *ConfigManager) updateDNS(ctx context.Context, c *dnssvc.Config) (err error) {
+	if prev := m.dns; prev != nil {
+		err = prev.Shutdown(ctx)
+		if err != nil {
+			return fmt.Errorf("shutting down dns svc: %w", err)
+		}
+	}
+
+	svc, err := dnssvc.New(c)
+	if err != nil {
+		return fmt.Errorf("creating dns svc: %w", err)
+	}
+
+	m.dns = svc
+
+	return nil
+}
+
+// Web returns the current web service.  It is safe for concurrent use.
+func (m *ConfigManager) Web() (web agh.ServiceWithConfig[*websvc.Config]) {
+	m.updMu.RLock()
+	defer m.updMu.RUnlock()
+
+	return m.web
+}
+
+// UpdateWeb implements the websvc.ConfigManager interface for *ConfigManager.
+// The fields of c must not be modified after calling UpdateWeb.
+func (m *ConfigManager) UpdateWeb(ctx context.Context, c *websvc.Config) (err error) {
+	m.updMu.Lock()
+	defer m.updMu.Unlock()
+
+	// TODO(a.garipov): Update and write the configuration file.  Return an
+	// error if something went wrong.
+
+	err = m.updateWeb(ctx, c)
+	if err != nil {
+		return fmt.Errorf("reassembling websvc: %w", err)
+	}
+
+	return nil
+}
+
+// updateWeb recreates the web service.  m.upd is expected to be locked.
+func (m *ConfigManager) updateWeb(ctx context.Context, c *websvc.Config) (err error) {
+	if prev := m.web; prev != nil {
+		err = prev.Shutdown(ctx)
+		if err != nil {
+			return fmt.Errorf("shutting down web svc: %w", err)
+		}
+	}
+
+	m.web = websvc.New(c)
+
+	return nil
+}
diff --git a/internal/next/svc/svc.go b/internal/next/svc/svc.go
new file mode 100644
index 00000000000..6c98d73492e
--- /dev/null
+++ b/internal/next/svc/svc.go
@@ -0,0 +1,3 @@
+// Package svc defines the AdGuard Home service locator, assembler, as well as
+// on-disk configuration manager.
+package svc
diff --git a/internal/next/websvc/dns_test.go b/internal/next/websvc/dns_test.go
index f774c3d87dd..d0efec8734a 100644
--- a/internal/next/websvc/dns_test.go
+++ b/internal/next/websvc/dns_test.go
@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
+	"github.com/AdguardTeam/AdGuardHome/internal/next/agh"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/dnssvc"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/websvc"
 	"github.com/stretchr/testify/assert"
@@ -28,7 +29,7 @@ func TestService_HandlePatchSettingsDNS(t *testing.T) {
 	// TODO(a.garipov): Use [atomic.Bool] in Go 1.19.
 	var numStarted uint64
 	confMgr := newConfigManager()
-	confMgr.onDNS = func() (s websvc.ServiceWithConfig[*dnssvc.Config]) {
+	confMgr.onDNS = func() (s agh.ServiceWithConfig[*dnssvc.Config]) {
 		return &aghtest.ServiceWithConfig[*dnssvc.Config]{
 			OnStart: func() (err error) {
 				atomic.AddUint64(&numStarted, 1)
diff --git a/internal/next/websvc/http.go b/internal/next/websvc/http.go
index b58eecb9499..c6107cd0501 100644
--- a/internal/next/websvc/http.go
+++ b/internal/next/websvc/http.go
@@ -8,6 +8,7 @@ import (
 	"net/netip"
 	"time"
 
+	"github.com/AdguardTeam/AdGuardHome/internal/next/agh"
 	"github.com/AdguardTeam/golibs/log"
 )
 
@@ -89,7 +90,7 @@ func (svc *Service) handlePatchSettingsHTTP(w http.ResponseWriter, r *http.Reque
 		// TODO(a.garipov): Consider better ways to do this.
 		const maxUpdDur = 10 * time.Second
 		updStart := time.Now()
-		var newSvc ServiceWithConfig[*Config]
+		var newSvc agh.ServiceWithConfig[*Config]
 		for newSvc = svc.confMgr.Web(); newSvc == svc; {
 			if time.Since(updStart) >= maxUpdDur {
 				log.Error("websvc: failed to update svc after %s", maxUpdDur)
diff --git a/internal/next/websvc/http_test.go b/internal/next/websvc/http_test.go
index baf384da296..d79be735d88 100644
--- a/internal/next/websvc/http_test.go
+++ b/internal/next/websvc/http_test.go
@@ -10,6 +10,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/AdguardTeam/AdGuardHome/internal/next/agh"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/websvc"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -24,7 +25,7 @@ func TestService_HandlePatchSettingsHTTP(t *testing.T) {
 	}
 
 	confMgr := newConfigManager()
-	confMgr.onWeb = func() (s websvc.ServiceWithConfig[*websvc.Config]) {
+	confMgr.onWeb = func() (s agh.ServiceWithConfig[*websvc.Config]) {
 		return websvc.New(&websvc.Config{
 			TLS: &tls.Config{
 				Certificates: []tls.Certificate{{}},
diff --git a/internal/next/websvc/settings_test.go b/internal/next/websvc/settings_test.go
index dadb4b55ea3..3dfc63fc8a2 100644
--- a/internal/next/websvc/settings_test.go
+++ b/internal/next/websvc/settings_test.go
@@ -9,6 +9,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/AdguardTeam/AdGuardHome/internal/next/agh"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/dnssvc"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/websvc"
 	"github.com/stretchr/testify/assert"
@@ -33,7 +34,7 @@ func TestService_HandleGetSettingsAll(t *testing.T) {
 	}
 
 	confMgr := newConfigManager()
-	confMgr.onDNS = func() (s websvc.ServiceWithConfig[*dnssvc.Config]) {
+	confMgr.onDNS = func() (s agh.ServiceWithConfig[*dnssvc.Config]) {
 		c, err := dnssvc.New(&dnssvc.Config{
 			Addresses:        wantDNS.Addresses,
 			UpstreamServers:  wantDNS.UpstreamServers,
@@ -45,7 +46,7 @@ func TestService_HandleGetSettingsAll(t *testing.T) {
 		return c
 	}
 
-	confMgr.onWeb = func() (s websvc.ServiceWithConfig[*websvc.Config]) {
+	confMgr.onWeb = func() (s agh.ServiceWithConfig[*websvc.Config]) {
 		return websvc.New(&websvc.Config{
 			TLS: &tls.Config{
 				Certificates: []tls.Certificate{{}},
diff --git a/internal/next/websvc/websvc.go b/internal/next/websvc/websvc.go
index 75f7d001f69..054228897a1 100644
--- a/internal/next/websvc/websvc.go
+++ b/internal/next/websvc/websvc.go
@@ -24,21 +24,10 @@ import (
 	httptreemux "github.com/dimfeld/httptreemux/v5"
 )
 
-// ServiceWithConfig is an extension of the [agh.Service] interface for services
-// that can return their configuration.
-//
-// TODO(a.garipov): Consider removing this generic interface if we figure out
-// how to make it testable in a better way.
-type ServiceWithConfig[ConfigType any] interface {
-	agh.Service
-
-	Config() (c ConfigType)
-}
-
 // ConfigManager is the configuration manager interface.
 type ConfigManager interface {
-	DNS() (svc ServiceWithConfig[*dnssvc.Config])
-	Web() (svc ServiceWithConfig[*Config])
+	DNS() (svc agh.ServiceWithConfig[*dnssvc.Config])
+	Web() (svc agh.ServiceWithConfig[*Config])
 
 	UpdateDNS(ctx context.Context, c *dnssvc.Config) (err error)
 	UpdateWeb(ctx context.Context, c *Config) (err error)
diff --git a/internal/next/websvc/websvc_test.go b/internal/next/websvc/websvc_test.go
index dbce77d58a2..39ab30389df 100644
--- a/internal/next/websvc/websvc_test.go
+++ b/internal/next/websvc/websvc_test.go
@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/aghtest"
+	"github.com/AdguardTeam/AdGuardHome/internal/next/agh"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/dnssvc"
 	"github.com/AdguardTeam/AdGuardHome/internal/next/websvc"
 	"github.com/AdguardTeam/golibs/testutil"
@@ -34,20 +35,20 @@ var _ websvc.ConfigManager = (*configManager)(nil)
 
 // configManager is a [websvc.ConfigManager] for tests.
 type configManager struct {
-	onDNS func() (svc websvc.ServiceWithConfig[*dnssvc.Config])
-	onWeb func() (svc websvc.ServiceWithConfig[*websvc.Config])
+	onDNS func() (svc agh.ServiceWithConfig[*dnssvc.Config])
+	onWeb func() (svc agh.ServiceWithConfig[*websvc.Config])
 
 	onUpdateDNS func(ctx context.Context, c *dnssvc.Config) (err error)
 	onUpdateWeb func(ctx context.Context, c *websvc.Config) (err error)
 }
 
 // DNS implements the [websvc.ConfigManager] interface for *configManager.
-func (m *configManager) DNS() (svc websvc.ServiceWithConfig[*dnssvc.Config]) {
+func (m *configManager) DNS() (svc agh.ServiceWithConfig[*dnssvc.Config]) {
 	return m.onDNS()
 }
 
 // Web implements the [websvc.ConfigManager] interface for *configManager.
-func (m *configManager) Web() (svc websvc.ServiceWithConfig[*websvc.Config]) {
+func (m *configManager) Web() (svc agh.ServiceWithConfig[*websvc.Config]) {
 	return m.onWeb()
 }
 
@@ -64,8 +65,8 @@ func (m *configManager) UpdateWeb(ctx context.Context, c *websvc.Config) (err er
 // newConfigManager returns a *configManager all methods of which panic.
 func newConfigManager() (m *configManager) {
 	return &configManager{
-		onDNS: func() (svc websvc.ServiceWithConfig[*dnssvc.Config]) { panic("not implemented") },
-		onWeb: func() (svc websvc.ServiceWithConfig[*websvc.Config]) { panic("not implemented") },
+		onDNS: func() (svc agh.ServiceWithConfig[*dnssvc.Config]) { panic("not implemented") },
+		onWeb: func() (svc agh.ServiceWithConfig[*websvc.Config]) { panic("not implemented") },
 		onUpdateDNS: func(_ context.Context, _ *dnssvc.Config) (err error) {
 			panic("not implemented")
 		},
diff --git a/scripts/make/go-build.sh b/scripts/make/go-build.sh
index c998a61168d..8d993d66fb5 100644
--- a/scripts/make/go-build.sh
+++ b/scripts/make/go-build.sh
@@ -124,11 +124,11 @@ GO111MODULE='on'
 export CGO_ENABLED GO111MODULE
 
 # Build the new binary if requested.
-if [ "${V1API:-0}" -eq '0' ]
+if [ "${NEXTAPI:-0}" -eq '0' ]
 then
 	tags_flags='--tags='
 else
-	tags_flags='--tags=v1'
+	tags_flags='--tags=next'
 fi
 readonly tags_flags