LogDog: Add collector service implementation.

server/internal/logdog/service/service.go

Index: server/internal/logdog/service/service.go
diff --git a/server/internal/logdog/service/service.go b/server/internal/logdog/service/service.go
new file mode 100644
index 0000000000000000000000000000000000000000..0826190bfc6500dd2224ed792c71ea89c7fa0c16
--- /dev/null
+++ b/server/internal/logdog/service/service.go
@@ -0,0 +1,284 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package service
+
+import (
+	"errors"
+	"flag"
+	"net/http"
+	"os"
+	"os/signal"
+	"sync"
+
+	"github.com/luci/luci-go/client/authcli"
+	"github.com/luci/luci-go/common/auth"
+	log "github.com/luci/luci-go/common/logging"
+	"github.com/luci/luci-go/common/logging/gologger"
+	"github.com/luci/luci-go/common/proto/logdog/svcconfig"
+	"github.com/luci/luci-go/server/internal/logdog/config"
+	"github.com/luci/luci-go/server/internal/logdog/coordinatorClient"
+	"github.com/luci/luci-go/server/logdog/storage"
+	"github.com/luci/luci-go/server/logdog/storage/bigtable"
+	"golang.org/x/net/context"
+	"google.golang.org/cloud"
+)
+
+var (
+	// ErrInvalidConfig is an error that is returned when the supplied
+	// configuration is invalid.
+	ErrInvalidConfig = errors.New("invalid configuration")
+)
+
+// Service is a base class full of common LogDog service application parameters.
+type Service struct {
+	context.Context
+
+	// UserAgent is the user agent string that will be used for service
+	// communication.
+	UserAgent string
+
+	// ShutdownFunc, if not nil, is a function that will be called when a shutdown
+	// signal is received.
+	ShutdownFunc func()
+
+	// topCancelFunc is the Context cancel function for the top-level application
+	// Context.
+	topCancelFunc func()
+
+	// shutdownMu protects the shutdown variables.
+	shutdownMu    sync.Mutex
+	shutdownFunc  func()
+	shutdownCount int32
+
+	loggingFlags log.Config
+	authFlags    authcli.Flags
+	configFlags  config.Flags
+
+	coordinatorURL            string
+	storageCredentialJSONPath string
+
+	coord  *coordinatorClient.Client
+	config *config.Manager
+}
+
+// New instantiates a new Service.
+func New(c context.Context) *Service {
+	c, cancelFunc := context.WithCancel(c)
+	c = gologger.Use(c)
+
+	return &Service{
+		Context:       c,
+		topCancelFunc: cancelFunc,
+	}
+}
+
+// AddFlags adds standard service flags to the supplied FlagSet.
+func (s *Service) AddFlags(fs *flag.FlagSet) {
+	s.loggingFlags.AddFlags(fs)
+	s.authFlags.Register(fs, auth.Options{
+		Context: s,
+		Logger:  log.Get(s),
+	})
+	s.configFlags.AddToFlagSet(fs)
+
+	fs.StringVar(&s.coordinatorURL, "coordinator-url", "",
+		"The URL of the Coordinator service to use.")
+	fs.StringVar(&s.storageCredentialJSONPath, "storage-credential-json-path", "",
+		"If supplied, the path of a JSON credential file to load and use for storage operations.")
+}
+
+// Run loads the Service's base runtime and invokes the specified run function.
+func (s *Service) Run(f func() error) error {
+	s.Context = s.loggingFlags.Set(s.Context)
+
+	// Configure our signal handler. It will listen for terminating signals and
+	// issue a shutdown signal if one is received.
+	signalC := make(chan os.Signal)
+	go func() {
+		for sig := range signalC {
+			s.Shutdown()
+			log.Warningf(log.SetField(s, "signal", sig), "Received close signal. Send again to terminate immediately.")
+		}
+	}()
+	signal.Notify(signalC, os.Interrupt)
+	defer func() {
+		signal.Stop(signalC)
+		close(signalC)
+	}()
+
+	// Setup our Coordinator client.
+	var err error
+	s.coord, err = s.initCoordinatorClient()
+	if err != nil {
+		log.Errorf(log.SetError(s, err), "Failed to setup Coordinator client.")
+		return err
+	}
+
+	s.config, err = s.initConfig()
+	if err != nil {
+		log.Errorf(log.SetError(s, err), "Failed to setup configuration.")
+		return err
+	}
+
+	return f()
+}
+
+func (s *Service) initCoordinatorClient() (*coordinatorClient.Client, error) {
+	if s.coordinatorURL == "" {
+		log.Errorf(s, "Missing Coordinator URL (-coordinator-url).")
+		return nil, ErrInvalidConfig
+	}
+
+	client, err := s.AuthenticatedClient(func(o *auth.Options) {
+		o.Scopes = coordinatorClient.ServiceScopes
+	})
+	if err != nil {
+		log.Errorf(log.SetError(s, err), "Failed to create Coordinator client.")
+		return nil, err
+	}
+
+	return coordinatorClient.New(coordinatorClient.Options{
+		Client:    client,
+		BasePath:  s.coordinatorURL,
+		UserAgent: s.UserAgent,
+	}), nil
+}
+
+func (s *Service) initConfig() (*config.Manager, error) {
+	rt, err := s.AuthenticatedTransport(nil)
+	if err != nil {
+		log.Errorf(log.SetError(s, err), "Failed to create config client.")
+		return nil, err
+	}
+
+	s.configFlags.RoundTripper = rt
+	o, err := s.configFlags.CoordinatorOptions(s, s.coord)
+	if err != nil {
+		log.Errorf(log.SetError(s, err), "Failed to load configuration parameters.")
+		return nil, err
+	}
+	o.KillFunc = s.Shutdown
+
+	return config.NewManager(s, *o)
+}
+
+// Shutdown issues a shutdown signal to the service.
+func (s *Service) Shutdown() {
+	s.shutdownMu.Lock()
+	defer s.shutdownMu.Unlock()
+
+	if s.shutdownCount > 0 {
+		os.Exit(1)
+	}
+	s.shutdownCount++
+
+	if f := s.shutdownFunc; f != nil {
+		f()
+	} else {
+		s.topCancelFunc()
+	}
+}
+
+// SetShutdownFunc sets the service shutdown function.
+func (s *Service) SetShutdownFunc(f func()) {
+	s.shutdownMu.Lock()
+	defer s.shutdownMu.Unlock()
+	s.shutdownFunc = f
+}
+
+// Config returns the cached service configuration.
+func (s *Service) Config() *svcconfig.Config {
+	return s.config.Config()
+}
+
+// Coordinator returns the cached Coordinator client.
+func (s *Service) Coordinator() *coordinatorClient.Client {
+	return s.coord
+}
+
+// Storage instantiates the configured Storage instance.
+func (s *Service) Storage() (storage.Storage, error) {
+	cfg := s.config.Config()
+	if cfg.GetStorage() == nil {
+		log.Errorf(s, "Missing storage configuration.")
+		return nil, ErrInvalidConfig
+	}
+
+	btcfg := cfg.GetStorage().GetBigtable()
+	if btcfg == nil {
+		log.Errorf(s, "Missing BigTable storage configuration")
+		return nil, ErrInvalidConfig
+	}
+
+	// Initialize Storage authentication.
+	a, err := s.Authenticator(func(o *auth.Options) {
+		o.Scopes = bigtable.StorageScopes
+		if s.storageCredentialJSONPath != "" {
+			o.ServiceAccountJSONPath = s.storageCredentialJSONPath
+		}
+	})
+	if err != nil {
+		log.Errorf(log.SetError(s, err), "Failed to create BigTable Authenticator.")
+		return nil, err
+	}
+
+	bt, err := bigtable.New(s, bigtable.Options{
+		Project:  btcfg.Project,
+		Zone:     btcfg.Zone,
+		Cluster:  btcfg.Cluster,
+		LogTable: btcfg.LogTableName,
+		ClientOptions: []cloud.ClientOption{
+			cloud.WithTokenSource(a.TokenSource()),
+		},
+	})
+	if err != nil {
+		log.Errorf(log.SetError(s, err), "Failed to create BigTable instance.")
+		return nil, err
+	}
+	return bt, nil
+}
+
+// Authenticator returns an Authenticator instance. The Authenticator is
+// configured from a base set of Authenticator Options.
+//
+// An optional permutation functon can be provided to modify those Options
+// before the Authenticator is created.
+func (s *Service) Authenticator(f func(o *auth.Options)) (*auth.Authenticator, error) {
+	authOpts, err := s.authFlags.Options()
+	if err != nil {
+		log.Errorf(log.SetError(s, err), "Failed to create authenticator options.")
+		return nil, ErrInvalidConfig
+	}
+	if f != nil {
+		f(&authOpts)
+	}
+	return auth.NewAuthenticator(auth.SilentLogin, authOpts), nil
+}
+
+// AuthenticatedTransport returns an authenticated http.RoundTripper transport.
+// The transport is configured from a base set of Authenticator Options.
+//
+// An optional permutation functon can be provided to modify those Options
+// before the Authenticator is created.
+func (s *Service) AuthenticatedTransport(f func(o *auth.Options)) (http.RoundTripper, error) {
+	a, err := s.Authenticator(f)
+	if err != nil {
+		return nil, err
+	}
+	return a.Transport()
+}
+
+// AuthenticatedClient returns an authenticated http.Client. The Client is
+// configured from a base set of Authenticator Options.
+//
+// An optional permutation functon can be provided to modify those Options
+// before the Authenticator is created.
+func (s *Service) AuthenticatedClient(f func(o *auth.Options)) (*http.Client, error) {
+	a, err := s.Authenticator(f)
+	if err != nil {
+		return nil, err
+	}
+	return a.Client()
+}