mongo: configuration, sync with py args

+ tidy

pkg/mongo/mongo.go

@@ -17,7 +17,18 @@ func GlobalTimeout(ctx context.Context) context.Context {
 	return ctx
 }
 
-func Initialize(ctx context.Context, uri string, opts *mongoOpt.ClientOptions) (*mongo.Collection, error) {
+type InitializeOptions struct {
+	MaxPoolSize        uint64
+	CapSizeBytes       int64
+	ExpireAfterSeconds int64
+}
+
+func Initialize(ctx context.Context, uri string, opt *InitializeOptions) (*mongo.Collection, error) {
+	collectionName := "logs"
+	if opt == nil {
+		opt = &InitializeOptions{}
+	}
+
 	uriParsed, err := url.ParseRequestURI(uri)
 	if err != nil {
 		return nil, fmt.Errorf("parsing URI for database name: %w", err)
@@ -28,7 +39,7 @@ func Initialize(ctx context.Context, uri string, opts *mongoOpt.ClientOptions) (
 		return nil, fmt.Errorf("URI must include database name (as database to authenticate against)")
 	}
 
-	dbOpt := attachMetrics(opts).ApplyURI(uri)
+	dbOpt := attachMetrics(mongoOpt.Client()).ApplyURI(uri).SetMaxPoolSize(opt.MaxPoolSize)
 
 	dbClient, err := mongo.Connect(GlobalTimeout(ctx), dbOpt)
 	if err != nil {
@@ -39,7 +50,19 @@ func Initialize(ctx context.Context, uri string, opts *mongoOpt.ClientOptions) (
 		return nil, fmt.Errorf("first ping to database: %w", err)
 	}
 
-	col := dbClient.Database(uriParsed.Path).Collection("logs")
+	db := dbClient.Database(uriParsed.Path)
+
+	capped := opt.CapSizeBytes > 0
+
+	if err := db.CreateCollection(GlobalTimeout(ctx), collectionName, &mongoOpt.CreateCollectionOptions{
+		Capped:             &capped,
+		SizeInBytes:        &opt.CapSizeBytes,
+		ExpireAfterSeconds: &opt.ExpireAfterSeconds,
+	}); err != nil {
+		return nil, fmt.Errorf("initializing collection")
+	}
+
+	col := db.Collection(collectionName)
 
 	if err := InitializeIndexes(GlobalTimeout(ctx), col); err != nil {
 		return nil, fmt.Errorf("initializing indexes: %w", err)