Configuration

flagd supports configuration via config file, environment variables and flags. In cases of conflict, flags have the highest priority, followed by environment variables and finally config file.

Supported flags are documented (auto-generated) here.

Environment variable keys are uppercased, prefixed with FLAGD_ and all - are replaced with _. For example, sync-provider-args in environment variable form is FLAGD_SYNC_PROVIDER_ARGS.

Config file expects the keys to have the exact naming as the flags.

URI patterns

Any URI passed to flagd via the --uri flag must follow one of the 4 following patterns to ensure that it is passed to the correct implementation:

Sync	Pattern	Example
Kubernetes	core.openfeature.dev/namespace/name	core.openfeature.dev/default/my-crd
Filepath	file:path/to/my/flag	file:etc/flagd/my-flags.json
Remote	http(s)://flag-source-url	https://my-flags.com/flags
Grpc	grpc(s)://flag-source-url	grpc://my-flags-server

Customising sync providers

Custom sync providers can be used to provide flag evaluation logic.

Kubernetes provider

The Kubernetes provider allows flagD to connect to a Kubernetes cluster and evaluate flags against a specified FeatureFlagConfiguration resource as defined within the open-feature-operator spec.

To use an existing FeatureFlagConfiguration custom resource, start flagD with the following command:

flagd start --uri core.openfeature.dev/default/my_example

Source Configuration

While a URI may be passed to flagd via the --uri flag, some implementations may require further configurations. In these cases the --sources flag should be used. The flag takes a string argument, which should be a JSON representation of an array of SourceConfig objects. Alternatively, these configurations should be passed to flagd via config file, specified using the --config flag.

Field	Type	Note
uri	required string
provider	required string (file, kubernetes, http or grpc)
bearerToken	optional string	Used for http sync
certPath	optional string	Used for grpcs sync when TLS certificate is needed

The uri field values do not need to follow the URI patterns, the provider type is instead derived from the provider field. If the prefix is supplied, it will be removed on startup without error.

Example start command using a filepath sync provider and the equivalent config file definition:

./bin/flagd start --sources='[{"uri":"config/samples/example_flags.json","provider":"file"},{"uri":"http://my-flag-source.json","provider":"http","bearerToken":"bearer-dji34ld2l"}]{"uri":"default/my-flag-config","provider":"kubernetes"},{"uri":"grpc://my-flag-source:8080","provider":"grpc"}'

sources:
- uri: config/samples/example_flags.json
  provider: file
- uri: http://my-flag-source.json
  provider: http
  bearerToken: bearer-dji34ld2l
- uri: default/my-flag-config
  provider: kubernetes
- uri: http://my-flag-source.json
  provider: kubernetes
- uri: grpc://my-flag-source:8080
  provider: grpc
- uri: grpcs://my-flag-source:8080
  provider: grpc
  certPath: /certs/ca.cert