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Node.js provider



npm install @openfeature/flagd-provider


yarn add @openfeature/server-sdk @grpc/grpc-js @openfeature/flagd-core

[!NOTE] yarn requires manual installation of peer dependencies

Configurations and Usage

The FlagdProvider supports multiple configuration options and has the ability to resolve flags remotely over RPC or in-process. Options can be defined in the constructor or as environment variables. Constructor options having the highest precedence.

Available Configuration Options

Option name Environment variable name Type Default Supported values
host FLAGD_HOST string localhost
port FLAGD_PORT number 8013
tls FLAGD_TLS boolean false
socketPath FLAGD_SOCKET_PATH string -
resolverType FLAGD_RESOLVER string rpc rpc, in-process
offlineFlagSourcePath FLAGD_OFFLINE_FLAG_SOURCE_PATH string -
selector FLAGD_SOURCE_SELECTOR string -
cache FLAGD_CACHE string lru lru, disabled
maxCacheSize FLAGD_MAX_CACHE_SIZE int 1000

Below are examples of usage patterns.

Remote flag resolving over RPC

This is the default mode of operation of the provider. In this mode, FlagdProvider communicates with flagd via the gRPC protocol. Flag evaluations take place remotely on the connected flagd instance.

  OpenFeature.setProvider(new FlagdProvider())

In the above example, the provider expects flagd to be available at localhost:8013 (default host and port).

Alternatively, you can use socket paths to connect to flagd.

  OpenFeature.setProvider(new FlagdProvider({
      socketPath: "/tmp/flagd.socks",

In-process resolver

This mode performs flag evaluations locally (in-process). Flag configurations for evaluation are obtained via gRPC protocol using sync protobuf schema service definition.

  OpenFeature.setProvider(new FlagdProvider({
      resolverType: 'in-process',

In the above example, the provider expects a flag sync service implementation to be available at localhost:8013 (default host and port).

In-process resolver can also work in an offline mode. To enable this mode, you should provide a valid flag configuration file with the option offlineFlagSourcePath.

  OpenFeature.setProvider(new FlagdProvider({
      resolverType: 'in-process',
      offlineFlagSourcePath: './flags.json',

Offline mode uses fs.watchFile and polls every 5 seconds for changes to the file. This mode is useful for local development, test cases, and for offline applications.

Supported Events


SDK event Originating action in flagd
PROVIDER_READY The streaming connection with flagd has been established.
PROVIDER_ERROR The streaming connection with flagd has been broken.
PROVIDER_CONFIGURATION_CHANGED A flag configuration (default value, targeting rule, etc) in flagd has changed.

For general information on events, see the official documentation.

Flag Metadata

Field Type Value
scope string "selector" set for the associated source in flagd