integrates an APNs pusher into data service

If the necessary configuration isn't found, then push notifications will
instead be logged.

BACK-2554

alerts/config.go

@@ -269,3 +269,11 @@ type Repository interface {
 
 	EnsureIndexes() error
 }
+
+// Note gathers information necessary for sending an alert notification.
+type Note struct {
+	// Message communicates the alert to the recipient.
+	Message         string
+	RecipientUserID string
+	FollowedUserID  string
+}

data/service/service/standard.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/Shopify/sarama"
+	"github.com/kelseyhightower/envconfig"
 	eventsCommon "github.com/tidepool-org/go-common/events"
 
 	"github.com/tidepool-org/platform/application"
@@ -17,13 +18,15 @@ import (
 	dataSourceStoreStructured "github.com/tidepool-org/platform/data/source/store/structured"
 	dataSourceStoreStructuredMongo "github.com/tidepool-org/platform/data/source/store/structured/mongo"
 	dataStoreMongo "github.com/tidepool-org/platform/data/store/mongo"
+	"github.com/tidepool-org/platform/devicetokens"
 	"github.com/tidepool-org/platform/errors"
 	"github.com/tidepool-org/platform/events"
 	"github.com/tidepool-org/platform/log"
 	metricClient "github.com/tidepool-org/platform/metric/client"
 	"github.com/tidepool-org/platform/permission"
 	permissionClient "github.com/tidepool-org/platform/permission/client"
 	"github.com/tidepool-org/platform/platform"
+	"github.com/tidepool-org/platform/push"
 	"github.com/tidepool-org/platform/service/server"
 	"github.com/tidepool-org/platform/service/service"
 	storeStructuredMongo "github.com/tidepool-org/platform/store/structured/mongo"
@@ -41,6 +44,7 @@ type Standard struct {
 	dataClient                *Client
 	clinicsClient             *clinics.Client
 	dataSourceClient          *dataSourceServiceClient.Client
+	pusher                    Pusher
 	userEventsHandler         events.Runner
 	api                       *api.Standard
 	server                    *server.Standard
@@ -87,6 +91,9 @@ func (s *Standard) Initialize(provider application.Provider) error {
 	if err := s.initializeSaramaLogger(); err != nil {
 		return err
 	}
+	if err := s.initializePusher(); err != nil {
+		return err
+	}
 	if err := s.initializeUserEventsHandler(); err != nil {
 		return err
 	}
@@ -426,3 +433,34 @@ func (s *Standard) initializeSaramaLogger() error {
 	sarama.Logger = log.NewSarama(s.Logger())
 	return nil
 }
+
+// Pusher is a service-agnostic interface for sending push notifications.
+type Pusher interface {
+	// Push a notification to a device.
+	Push(context.Context, *devicetokens.DeviceToken, *push.Notification) error
+}
+
+func (s *Standard) initializePusher() error {
+	var err error
+
+	apns2Config := &struct {
+		SigningKey []byte `envconfig:"TIDEPOOL_DATA_SERVICE_PUSHER_APNS_SIGNING_KEY"`
+		KeyID      string `envconfig:"TIDEPOOL_DATA_SERVICE_PUSHER_APNS_KEY_ID"`
+		BundleID   string `envconfig:"TIDEPOOL_DATA_SERVICE_PUSHER_APNS_BUNDLE_ID"`
+		TeamID     string `envconfig:"TIDEPOOL_DATA_SERVICE_PUSHER_APNS_TEAM_ID"`
+	}{}
+	if err := envconfig.Process("", apns2Config); err != nil {
+		return errors.Wrap(err, "Unable to process APNs pusher config")
+	}
+
+	var pusher Pusher
+	pusher, err = push.NewAPNSPusherFromKeyData(apns2Config.SigningKey, apns2Config.KeyID,
+		apns2Config.TeamID, apns2Config.BundleID)
+	if err != nil {
+		s.Logger().WithError(err).Warn("falling back to logging of push notifications")
+		pusher = push.NewLogPusher(s.Logger())
+	}
+	s.pusher = pusher
+
+	return nil
+}

push/logpush.go

@@ -0,0 +1,39 @@
+package push
+
+import (
+	"context"
+	"os"
+
+	"github.com/tidepool-org/platform/devicetokens"
+	"github.com/tidepool-org/platform/log"
+	logjson "github.com/tidepool-org/platform/log/json"
+	lognull "github.com/tidepool-org/platform/log/null"
+)
+
+// LogPusher logs notifications instead of sending push notifications.
+//
+// Useful for dev or testing situations.
+type LogPusher struct {
+	log.Logger
+}
+
+// NewLogPusher uses a [log.Logger] instead of pushing via APNs.
+func NewLogPusher(l log.Logger) *LogPusher {
+	if l == nil {
+		var err error
+		l, err = logjson.NewLogger(os.Stderr, log.DefaultLevelRanks(), log.DefaultLevel())
+		if err != nil {
+			l = lognull.NewLogger()
+		}
+	}
+	return &LogPusher{Logger: l}
+}
+
+// Push implements [service.Pusher].
+func (p *LogPusher) Push(ctx context.Context, deviceToken *devicetokens.DeviceToken, note *Notification) error {
+	p.Logger.WithFields(log.Fields{
+		"deviceToken": deviceToken,
+		"note":        note,
+	}).Info("logging push notification")
+	return nil
+}

push/push.go

@@ -11,6 +11,7 @@ import (
 	"github.com/sideshow/apns2/payload"
 	"github.com/sideshow/apns2/token"
 
+	"github.com/tidepool-org/platform/alerts"
 	"github.com/tidepool-org/platform/devicetokens"
 	"github.com/tidepool-org/platform/errors"
 	"github.com/tidepool-org/platform/log"
@@ -21,6 +22,17 @@ type Notification struct {
 	Message string
 }
 
+// String implements fmt.Stringer.
+func (n Notification) String() string {
+	return n.Message
+}
+
+func FromNote(note *alerts.Note) *Notification {
+	return &Notification{
+		Message: note.Message,
+	}
+}
+
 // APNSPusher implements push notifications via Apple APNs.
 type APNSPusher struct {
 	BundleID string
@@ -47,6 +59,22 @@ func NewAPNSPusher(client APNS2Client, bundleID string) *APNSPusher {
 //
 // https://developer.apple.com/documentation/usernotifications/sending-notification-requests-to-apns
 func NewAPNSPusherFromKeyData(signingKey []byte, keyID, teamID, bundleID string) (*APNSPusher, error) {
+	if len(signingKey) == 0 {
+		return nil, errors.New("Unable to build APNSPusher: APNs signing key is blank")
+	}
+
+	if bundleID == "" {
+		return nil, errors.New("Unable to build APNSPusher: bundleID is blank")
+	}
+
+	if keyID == "" {
+		return nil, errors.New("Unable to build APNSPusher: keyID is blank")
+	}
+
+	if teamID == "" {
+		return nil, errors.New("Unable to build APNSPusher: teamID is blank")
+	}
+
 	authKey, err := token.AuthKeyFromBytes(signingKey)
 	if err != nil {
 		return nil, err