feat: introduce grpc sync for flagd

cmd/start.go

@@ -13,18 +13,18 @@ import (
 )
 
 const (
-	portFlagName           = "port"
+	bearerTokenFlagName    = "bearer-token"
+	corsFlagName           = "cors-origin"
+	evaluatorFlagName      = "evaluator"
+	logFormatFlagName      = "log-format"
 	metricsPortFlagName    = "metrics-port"
-	socketPathFlagName     = "socket-path"
+	portFlagName           = "port"
 	providerArgsFlagName   = "sync-provider-args"
-	evaluatorFlagName      = "evaluator"
 	serverCertPathFlagName = "server-cert-path"
 	serverKeyPathFlagName  = "server-key-path"
-	uriFlagName            = "uri"
-	bearerTokenFlagName    = "bearer-token"
-	corsFlagName           = "cors-origin"
+	socketPathFlagName     = "socket-path"
 	syncProviderFlagName   = "sync-provider"
-	logFormatFlagName      = "log-format"
+	uriFlagName            = "uri"
 )
 
 func init() {
@@ -46,7 +46,7 @@ func init() {
 		"a", nil, "Sync provider arguments as key values separated by =")
 	flags.StringSliceP(
 		uriFlagName, "f", []string{}, "Set a sync provider uri to read data from, this can be a filepath,"+
-			"url or FeatureFlagConfiguration. Using multiple providers is supported however if"+
+			"url (http and grpc) or FeatureFlagConfiguration. Using multiple providers is supported however if"+
 			" flag keys are duplicated across multiple sources it may lead to unexpected behavior. "+
 			"Please note that if you are using filepath, flagd only supports files with `.yaml/.yml/.json` extension.",
 	)
@@ -58,18 +58,18 @@ func init() {
 	)
 	flags.StringP(logFormatFlagName, "z", "console", "Set the logging format, e.g. console or json ")
 
-	_ = viper.BindPFlag(portFlagName, flags.Lookup(portFlagName))
+	_ = viper.BindPFlag(bearerTokenFlagName, flags.Lookup(bearerTokenFlagName))
+	_ = viper.BindPFlag(corsFlagName, flags.Lookup(corsFlagName))
+	_ = viper.BindPFlag(evaluatorFlagName, flags.Lookup(evaluatorFlagName))
+	_ = viper.BindPFlag(logFormatFlagName, flags.Lookup(logFormatFlagName))
 	_ = viper.BindPFlag(metricsPortFlagName, flags.Lookup(metricsPortFlagName))
-	_ = viper.BindPFlag(socketPathFlagName, flags.Lookup(socketPathFlagName))
+	_ = viper.BindPFlag(portFlagName, flags.Lookup(portFlagName))
 	_ = viper.BindPFlag(providerArgsFlagName, flags.Lookup(providerArgsFlagName))
-	_ = viper.BindPFlag(evaluatorFlagName, flags.Lookup(evaluatorFlagName))
 	_ = viper.BindPFlag(serverCertPathFlagName, flags.Lookup(serverCertPathFlagName))
 	_ = viper.BindPFlag(serverKeyPathFlagName, flags.Lookup(serverKeyPathFlagName))
-	_ = viper.BindPFlag(uriFlagName, flags.Lookup(uriFlagName))
-	_ = viper.BindPFlag(bearerTokenFlagName, flags.Lookup(bearerTokenFlagName))
-	_ = viper.BindPFlag(corsFlagName, flags.Lookup(corsFlagName))
+	_ = viper.BindPFlag(socketPathFlagName, flags.Lookup(socketPathFlagName))
 	_ = viper.BindPFlag(syncProviderFlagName, flags.Lookup(syncProviderFlagName))
-	_ = viper.BindPFlag(logFormatFlagName, flags.Lookup(logFormatFlagName))
+	_ = viper.BindPFlag(uriFlagName, flags.Lookup(uriFlagName))
 }
 
 // startCmd represents the start command
@@ -104,15 +104,15 @@ var startCmd = &cobra.Command{
 		}
 		// Build Runtime -----------------------------------------------------------
 		rt, err := runtime.FromConfig(logger, runtime.Config{
-			ServicePort:       viper.GetInt32(portFlagName),
+			CORS:              viper.GetStringSlice(corsFlagName),
 			MetricsPort:       viper.GetInt32(metricsPortFlagName),
-			ServiceSocketPath: viper.GetString(socketPathFlagName),
+			ProviderArgs:      viper.GetStringMapString(providerArgsFlagName),
 			ServiceCertPath:   viper.GetString(serverCertPathFlagName),
 			ServiceKeyPath:    viper.GetString(serverKeyPathFlagName),
-			ProviderArgs:      viper.GetStringMapString(providerArgsFlagName),
-			SyncURI:           viper.GetStringSlice(uriFlagName),
+			ServicePort:       viper.GetInt32(portFlagName),
+			ServiceSocketPath: viper.GetString(socketPathFlagName),
 			SyncBearerToken:   viper.GetString(bearerTokenFlagName),
-			CORS:              viper.GetStringSlice(corsFlagName),
+			SyncURI:           viper.GetStringSlice(uriFlagName),
 		})
 		if err != nil {
 			rtLogger.Fatal(err.Error())

docs/configuration/configuration.md

@@ -12,13 +12,14 @@ 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 3 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`       |
+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://flag-source-url`           | `grpc://my-flags-server`        |
 
 
 

docs/configuration/flagd_start.md

@@ -21,7 +21,7 @@ flagd start [flags]
   -d, --socket-path string                  Flagd socket path. With grpc the service will become available on this address. With http(s) the grpc-gateway proxy will use this address internally.
   -y, --sync-provider string                DEPRECATED: Set a sync provider e.g. filepath or remote
   -a, --sync-provider-args stringToString   Sync provider arguments as key values separated by = (default [])
-  -f, --uri .yaml/.yml/.json                Set a sync provider uri to read data from, this can be a filepath,url or FeatureFlagConfiguration. Using multiple providers is supported however if flag keys are duplicated across multiple sources it may lead to unexpected behavior. Please note that if you are using filepath, flagd only supports files with .yaml/.yml/.json extension.
+  -f, --uri .yaml/.yml/.json                Set a sync provider uri to read data from, this can be a filepath,url (http and grpc) or FeatureFlagConfiguration. Using multiple providers is supported however if flag keys are duplicated across multiple sources it may lead to unexpected behavior. Please note that if you are using filepath, flagd only supports files with .yaml/.yml/.json extension.
 ```
 
 ### Options inherited from parent commands

go.mod

@@ -4,8 +4,8 @@ go 1.19
 
 require (
 	buf.build/gen/go/open-feature/flagd/bufbuild/connect-go v1.4.1-20221226184428-0dc62ff103b8.1
-	buf.build/gen/go/open-feature/flagd/grpc/go v1.2.0-20221226184428-0dc62ff103b8.4
-	buf.build/gen/go/open-feature/flagd/protocolbuffers/go v1.28.1-20221226184428-0dc62ff103b8.4
+	buf.build/gen/go/open-feature/flagd/grpc/go v1.2.0-20230207182158-c211472558c3.4
+	buf.build/gen/go/open-feature/flagd/protocolbuffers/go v1.28.1-20230207182158-c211472558c3.4
 	github.com/bufbuild/connect-go v1.5.1
 	github.com/diegoholiveira/jsonlogic/v3 v3.2.7
 	github.com/dimiro1/banner v1.1.0

go.sum

@@ -2,10 +2,10 @@ buf.build/gen/go/grpc-ecosystem/grpc-gateway/grpc/go v1.2.0-20220906183531-bc28b
 buf.build/gen/go/grpc-ecosystem/grpc-gateway/protocolbuffers/go v1.28.1-20220906183531-bc28b723cd77.4/go.mod h1:92ejKVTiuvnKoAtRlpJpIxKfloI935DDqhs0NCRx+KM=
 buf.build/gen/go/open-feature/flagd/bufbuild/connect-go v1.4.1-20221226184428-0dc62ff103b8.1 h1:KoSPqmHyi3x27tPFLQ994CJjG4qc59v+0gbxY9+VXso=
 buf.build/gen/go/open-feature/flagd/bufbuild/connect-go v1.4.1-20221226184428-0dc62ff103b8.1/go.mod h1:68WGv4z/jXuTS3G7FEFQTEw4wiMmulBSX6BlSFX2Xc8=
-buf.build/gen/go/open-feature/flagd/grpc/go v1.2.0-20221226184428-0dc62ff103b8.4 h1:9ioWUVmnURL+TX4qVjyzzE3o9Z2ACDGidqtu9dkjmdY=
-buf.build/gen/go/open-feature/flagd/grpc/go v1.2.0-20221226184428-0dc62ff103b8.4/go.mod h1:mgJ/h6pO54DWEYi3YqzlLxFBerE6L4dPRPMIhKEGBw0=
-buf.build/gen/go/open-feature/flagd/protocolbuffers/go v1.28.1-20221226184428-0dc62ff103b8.4 h1:HMDOJt1SDrELWslNJWfjg4ItbNOPx3ZvD8RtikKr5SE=
-buf.build/gen/go/open-feature/flagd/protocolbuffers/go v1.28.1-20221226184428-0dc62ff103b8.4/go.mod h1:+Bnrjo56uVn/aBcLWchTveR8UeCj+KSJN4fE0xSmBNc=
+buf.build/gen/go/open-feature/flagd/grpc/go v1.2.0-20230207182158-c211472558c3.4 h1:11ayeHd1H1LhRuJlHzIfbcUk64gAtnm5zrBZXxoOyN0=
+buf.build/gen/go/open-feature/flagd/grpc/go v1.2.0-20230207182158-c211472558c3.4/go.mod h1:8ce/bdmiPVo2i5s+bYLENyIvi24dmBN5zy+nPyCUAHg=
+buf.build/gen/go/open-feature/flagd/protocolbuffers/go v1.28.1-20230207182158-c211472558c3.4 h1:6Ht0iYYWoG7qDuxGs/aG11uj9ulFfTL2zeWCryj9aWg=
+buf.build/gen/go/open-feature/flagd/protocolbuffers/go v1.28.1-20230207182158-c211472558c3.4/go.mod h1:+Bnrjo56uVn/aBcLWchTveR8UeCj+KSJN4fE0xSmBNc=
 cloud.google.com/go v0.26.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 cloud.google.com/go v0.38.0/go.mod h1:990N+gfupTy94rShfmMCWGDn0LpTmnzTp2qbd1dvSRU=
@@ -61,7 +61,6 @@ github.com/bufbuild/connect-go v1.5.1 h1:ORhrSiu63hWxtuMmC/V1mKySSRhEySsW5RkHJcy
 github.com/bufbuild/connect-go v1.5.1/go.mod h1:9iNvh/NOsfhNBUH5CtvXeVUskQO1xsrEviH7ZArwZ3I=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
-github.com/cespare/xxhash/v2 v2.1.2 h1:YRXhKfTDauu4ajMg1TPgFO5jnlC2HCbmLXMcTG5cbYE=
 github.com/cespare/xxhash/v2 v2.1.2/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
 github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
@@ -471,8 +470,6 @@ golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96b
 golang.org/x/net v0.0.0-20210525063256-abc453219eb5/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
 golang.org/x/net v0.0.0-20220225172249-27dd8689420f/go.mod h1:CfG3xpIq0wQ8r1q4Su4UZFWDARRcnwPjda9FqA0JpMk=
-golang.org/x/net v0.5.0 h1:GyT4nK/YDHSqa1c4753ouYCDajOYKTja9Xb/OHtgvSw=
-golang.org/x/net v0.5.0/go.mod h1:DivGGAXEgPSlEBzxGzZI+ZLohi+xUj054jfeKui00ws=
 golang.org/x/net v0.6.0 h1:L4ZwwTvKW9gr0ZMS1yrHD9GZhIuVjOBBnaKH+SPQK0Q=
 golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
 golang.org/x/net v0.7.0 h1:rJrUqqhjsgNp7KqAIc25s9pZnjU7TUcSY7HcVZjdn1g=
@@ -488,8 +485,6 @@ golang.org/x/oauth2 v0.0.0-20201208152858-08078c50e5b5/go.mod h1:KelEdhl1UZF7XfJ
 golang.org/x/oauth2 v0.0.0-20210218202405-ba52d332ba99/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
 golang.org/x/oauth2 v0.0.0-20210514164344-f6687ab2804c/go.mod h1:KelEdhl1UZF7XfJ4dDtk6s++YSgaE7mD/BuKKDLBl4A=
 golang.org/x/oauth2 v0.0.0-20220223155221-ee480838109b/go.mod h1:DAh4E804XQdzx2j+YRIaUnCqCV2RuMz24cGBJ5QYIrc=
-golang.org/x/oauth2 v0.0.0-20221014153046-6fdb5e3db783 h1:nt+Q6cXKz4MosCSpnbMtqiQ8Oz0pxTef2B4Vca2lvfk=
-golang.org/x/oauth2 v0.0.0-20221014153046-6fdb5e3db783/go.mod h1:h4gKUeWbJ4rQPri7E0u6Gs4e9Ri2zaLxzw5DI5XGrYg=
 golang.org/x/oauth2 v0.4.0 h1:NF0gk8LVPg1Ml7SSbGyySuoxdsXitj7TvgvuRxIMc/M=
 golang.org/x/oauth2 v0.4.0/go.mod h1:RznEsdpjGAINPTOF0UH/t+xJ75L18YO3Ho6Pyn+uRec=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -556,14 +551,10 @@ golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220114195835-da31bd327af9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.4.0 h1:Zr2JFtRQNX3BCZ8YtxRE9hNJYC8J6I1MVbMg6owUp18=
-golang.org/x/sys v0.4.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.5.0 h1:MUK/U/4lj1t1oPg0HfuXDN/Z1wv31ZJ/YcPiGccS4DU=
 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
-golang.org/x/term v0.4.0 h1:O7UWfv5+A2qiuulQk30kVinPoMtoIPeVaKLEgLpVkvg=
-golang.org/x/term v0.4.0/go.mod h1:9P2UbLfCdcvo3p/nzKvsmas4TnlujnuoV9hGgYzW1lQ=
 golang.org/x/term v0.5.0 h1:n2a8QNdAb0sZNpU9R1ALUXBbY+w51fCQDN+7EdxNBsY=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -574,8 +565,6 @@ golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.4/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
-golang.org/x/text v0.6.0 h1:3XmdazWV+ubf7QgHSTWeykHOci5oeekaGJBLkrkaw4k=
-golang.org/x/text v0.6.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/text v0.7.0 h1:4BRB4x83lYWy72KwLD/qYDuTu7q9PjSagHvijDw7cLo=
 golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
@@ -704,8 +693,6 @@ google.golang.org/genproto v0.0.0-20201210142538-e3217bee35cc/go.mod h1:FWY/as6D
 google.golang.org/genproto v0.0.0-20201214200347-8c77b98c765d/go.mod h1:FWY/as6DDZQgahTzZj3fqbO1CbirC29ZNUFHwi0/+no=
 google.golang.org/genproto v0.0.0-20210108203827-ffc7fda8c3d7/go.mod h1:FWY/as6DDZQgahTzZj3fqbO1CbirC29ZNUFHwi0/+no=
 google.golang.org/genproto v0.0.0-20210226172003-ab064af71705/go.mod h1:FWY/as6DDZQgahTzZj3fqbO1CbirC29ZNUFHwi0/+no=
-google.golang.org/genproto v0.0.0-20221227171554-f9683d7f8bef h1:uQ2vjV/sHTsWSqdKeLqmwitzgvjMl7o4IdtHwUDXSJY=
-google.golang.org/genproto v0.0.0-20221227171554-f9683d7f8bef/go.mod h1:RGgjbofJ8xD9Sq1VVhDM1Vok1vRONV+rg+CjzG4SZKM=
 google.golang.org/genproto v0.0.0-20230110181048-76db0878b65f h1:BWUVssLB0HVOSY78gIdvk1dTVYtT1y8SBWtPYuTJ/6w=
 google.golang.org/genproto v0.0.0-20230110181048-76db0878b65f/go.mod h1:RGgjbofJ8xD9Sq1VVhDM1Vok1vRONV+rg+CjzG4SZKM=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
@@ -727,8 +714,6 @@ google.golang.org/grpc v1.34.0/go.mod h1:WotjhfgOW/POjDeRt8vscBtXq+2VjORFy659qA5
 google.golang.org/grpc v1.35.0/go.mod h1:qjiiYl8FncCW8feJPdyg3v6XW24KsRHe+dy9BAGRRjU=
 google.golang.org/grpc v1.36.0/go.mod h1:qjiiYl8FncCW8feJPdyg3v6XW24KsRHe+dy9BAGRRjU=
 google.golang.org/grpc v1.43.0/go.mod h1:k+4IHHFw41K8+bbowsex27ge2rCb65oeWqe4jJ590SU=
-google.golang.org/grpc v1.52.3 h1:pf7sOysg4LdgBqduXveGKrcEwbStiK2rtfghdzlUYDQ=
-google.golang.org/grpc v1.52.3/go.mod h1:pu6fVzoFb+NBYNAvQL08ic+lvB2IojljRYuun5vorUY=
 google.golang.org/grpc v1.53.0 h1:LAv2ds7cmFV/XTS3XG1NneeENYrXGmorPxsBbptIjNc=
 google.golang.org/grpc v1.53.0/go.mod h1:OnIrk0ipVdj4N5d9IUoFUx72/VlD7+jUsHwZgwSMQpw=
 google.golang.org/protobuf v0.0.0-20200109180630-ec00e32a8dfd/go.mod h1:DFci5gLYBciE7Vtevhsrf46CRTquxDuWsQurQQe4oz8=

pkg/runtime/from_config.go

@@ -6,13 +6,13 @@ import (
 	"regexp"
 	"time"
 
-	"github.com/open-feature/flagd/pkg/sync/file"
-	httpSync "github.com/open-feature/flagd/pkg/sync/http"
-
 	"github.com/open-feature/flagd/pkg/eval"
 	"github.com/open-feature/flagd/pkg/logger"
 	"github.com/open-feature/flagd/pkg/service"
 	"github.com/open-feature/flagd/pkg/sync"
+	"github.com/open-feature/flagd/pkg/sync/file"
+	"github.com/open-feature/flagd/pkg/sync/grpc"
+	httpSync "github.com/open-feature/flagd/pkg/sync/http"
 	"github.com/open-feature/flagd/pkg/sync/kubernetes"
 	"github.com/robfig/cron"
 	"go.uber.org/zap"
@@ -21,12 +21,14 @@ import (
 var (
 	regCrd  *regexp.Regexp
 	regURL  *regexp.Regexp
+	regGRPC *regexp.Regexp
 	regFile *regexp.Regexp
 )
 
 func init() {
 	regCrd = regexp.MustCompile("^core.openfeature.dev/")
 	regURL = regexp.MustCompile("^https?://")
+	regGRPC = regexp.MustCompile("^" + grpc.Prefix)
 	regFile = regexp.MustCompile("^file:")
 }
 
@@ -99,9 +101,17 @@ func (r *Runtime) setSyncImplFromConfig(logger *logger.Logger) error {
 				Cron:         cron.New(),
 			})
 			rtLogger.Debug(fmt.Sprintf("using remote sync-provider for: %q", uri))
+		case regGRPC.Match(uriB):
+			r.SyncImpl = append(r.SyncImpl, &grpc.Sync{
+				Target: grpc.URLToGRPCTarget(uri),
+				Logger: logger.WithFields(
+					zap.String("component", "sync"),
+					zap.String("sync", "grpc"),
+				),
+			})
 		default:
-			return fmt.Errorf("invalid sync uri argument: %s, must start with 'file:', 'http(s)://', or 'core.openfeature.dev'",
-				uri)
+			return fmt.Errorf("invalid sync uri argument: %s, must start with 'file:', 'http(s)://', 'grpc://',"+
+				" or 'core.openfeature.dev'", uri)
 		}
 	}
 	return nil

pkg/runtime/runtime.go

@@ -35,6 +35,7 @@ type Config struct {
 
 	ProviderArgs    sync.ProviderArgs
 	SyncURI         []string
+	RemoteSyncType  string
 	SyncBearerToken string
 
 	CORS []string