databroker server backend config (#1127)

* config,docs: add databroker storage backend configuration

* cache: allow configuring which backend storage to use

Currently supported types are "memory", "redis".

internal/databroker/config.go

@@ -8,17 +8,22 @@ var (
 	DefaultDeletePermanentlyAfter = time.Hour
 	// DefaultBTreeDegree is the default number of items to store in each node of the BTree.
 	DefaultBTreeDegree = 8
+	// DefaultStorageType is the default storage type that Server use
+	DefaultStorageType = "memory"
 )
 
 type serverConfig struct {
-	deletePermanentlyAfter time.Duration
-	btreeDegree            int
+	deletePermanentlyAfter  time.Duration
+	btreeDegree             int
+	storageType             string
+	storageConnectionString string
 }
 
 func newServerConfig(options ...ServerOption) *serverConfig {
 	cfg := new(serverConfig)
 	WithDeletePermanentlyAfter(DefaultDeletePermanentlyAfter)(cfg)
 	WithBTreeDegree(DefaultBTreeDegree)(cfg)
+	WithStorageType(DefaultStorageType)(cfg)
 	for _, option := range options {
 		option(cfg)
 	}
@@ -43,3 +48,17 @@ func WithDeletePermanentlyAfter(dur time.Duration) ServerOption {
 		cfg.deletePermanentlyAfter = dur
 	}
 }
+
+// WithStorageType sets the storage type.
+func WithStorageType(typ string) ServerOption {
+	return func(cfg *serverConfig) {
+		cfg.storageType = typ
+	}
+}
+
+// WithStorageConnectionString sets the DSN for storage.
+func WithStorageConnectionString(connStr string) ServerOption {
+	return func(cfg *serverConfig) {
+		cfg.storageConnectionString = connStr
+	}
+}

internal/databroker/server.go

@@ -21,6 +21,7 @@ import (
 	"github.com/pomerium/pomerium/pkg/grpc/databroker"
 	"github.com/pomerium/pomerium/pkg/storage"
 	"github.com/pomerium/pomerium/pkg/storage/inmemory"
+	"github.com/pomerium/pomerium/pkg/storage/redis"
 )
 
 const (
@@ -278,10 +279,26 @@ func (srv *Server) getDB(recordType string) storage.Backend {
 		srv.mu.Lock()
 		db = srv.byType[recordType]
 		if db == nil {
-			db = inmemory.NewDB(recordType, srv.cfg.btreeDegree)
+			db = srv.newDB(recordType)
 			srv.byType[recordType] = db
 		}
 		srv.mu.Unlock()
 	}
 	return db
 }
+
+func (srv *Server) newDB(recordType string) storage.Backend {
+	switch srv.cfg.storageType {
+	case inmemory.Name:
+		return inmemory.NewDB(recordType, srv.cfg.btreeDegree)
+	case redis.Name:
+		db, err := redis.New(srv.cfg.storageConnectionString, recordType, int64(srv.cfg.deletePermanentlyAfter.Seconds()))
+		if err != nil {
+			srv.log.Error().Err(err).Msg("failed to create new redis storage")
+			return nil
+		}
+		return db
+	default:
+		return nil
+	}
+}