cmd: builderAPI flag in the cli for builder proposer (#834)

- skeleton of the builder-api flag for cmd and app (nothing wired up or any functionality)

category: feature 
ticket: #809

app/app.go

@@ -79,6 +79,7 @@ type Config struct {
 	JaegerService    string
 	SimnetBMock      bool
 	SimnetVMock      bool
+	BuilderAPI       bool
 
 	TestConfig TestConfig
 }
@@ -105,6 +106,8 @@ type TestConfig struct {
 	BroadcastCallback func(context.Context, core.Duty, core.PubKey, core.SignedData) error
 	// DisablePromWrap disables wrapping prometheus metrics with cluster identifiers.
 	DisablePromWrap bool
+	// BuilderAPI enables the builder API opt-in feature
+	BuilderAPI bool
 }
 
 // Run is the entrypoint for running a charon DVC instance.

cmd/run.go

@@ -66,6 +66,7 @@ func bindRunFlags(cmd *cobra.Command, config *app.Config) {
 	cmd.Flags().StringVar(&config.JaegerService, "jaeger-service", "charon", "Service name used for jaeger tracing.")
 	cmd.Flags().BoolVar(&config.SimnetBMock, "simnet-beacon-mock", false, "Enables an internal mock beacon node for running a simnet.")
 	cmd.Flags().BoolVar(&config.SimnetVMock, "simnet-validator-mock", false, "Enables an internal mock validator client when running a simnet. Requires simnet-beacon-mock.")
+	cmd.Flags().BoolVar(&config.BuilderAPI, "builder-api", false, "Enables the builder api. Will only produce builder blocks. Builder API must also be enabled on the validator client. Beacon node must be connected to a builder-relay to access the builder network.")
 
 	preRunE := cmd.PreRunE // Allow multiple wraps of PreRunE.
 	cmd.PreRunE = func(cmd *cobra.Command, args []string) error {

docs/configuration.md

@@ -85,6 +85,7 @@ Usage:
 Flags:
       --beacon-node-endpoint string     Beacon node endpoint URL. Deprecated, please use beacon-node-endpoints.
       --beacon-node-endpoints strings   Comma separated list of one or more beacon node endpoint URLs.
+      --builder-api                     Enables the builder api. Will only produce builder blocks. Builder API must also be enabled on the validator client. Beacon node must be connected to a builder-relay to access the builder network.
       --data-dir string                 The directory where charon will store all its internal data (default ".charon")
       --feature-set string              Minimum feature set to enable by default: alpha, beta, or stable. Warning: modify at own risk. (default "stable")
       --feature-set-disable strings     Comma-separated list of features to disable, overriding the default minimum feature set.