Gateway client script: added readme and json pretty print (#11361)

* Gateway client script: added readme and json pretty print

* Reading S4 payload from the file

core/scripts/gateway/client/README.md

@@ -0,0 +1,20 @@
+# A gateway client script
+
+This script is used to connect to a gateway server and send commands to it.
+
+## Usage
+
+All requests have to be signed on behalf of a user, you need to provide your private key in .env file, e.g.
+
+```
+PRIVATE_KEY=1a2b3c...
+```
+
+The script will automatically sign the message using the provided private key.
+Run the script without arguments to get the list of available commands.
+
+## Example
+
+```
+go run . -gateway_url https://01.functions-gateway.chain.link -don_id fun-avalanche-mainnet-2 -method secrets_list -message_id 123
+```

core/scripts/gateway/client/send_request.go

@@ -28,7 +28,7 @@ func main() {
 	s4SetSlotId := flag.Uint("s4_set_slot_id", 0, "S4 set slot ID")
 	s4SetVersion := flag.Uint64("s4_set_version", 0, "S4 set version")
 	s4SetExpirationPeriod := flag.Int64("s4_set_expiration_period", 60*60*1000, "S4 how long until the entry expires from now (in milliseconds)")
-	s4SetPayload := flag.String("s4_set_payload", "", "S4 set payload")
+	s4SetPayloadFile := flag.String("s4_set_payload_file", "", "S4 payload file to set secret")
 	repeat := flag.Bool("repeat", false, "Repeat sending the request every 10 seconds")
 	flag.Parse()
 
@@ -50,14 +50,24 @@ func main() {
 	}
 	address := crypto.PubkeyToAddress(key.PublicKey)
 
+	var s4SetPayload []byte
+	if *methodName == functions.MethodSecretsSet {
+		var err error
+		s4SetPayload, err = os.ReadFile(*s4SetPayloadFile)
+		if err != nil {
+			fmt.Println("error reading S4 payload file", err)
+			return
+		}
+	}
+
 	// build payload (if relevant)
 	var payloadJSON []byte
 	if *methodName == functions.MethodSecretsSet {
 		envelope := s4.Envelope{
 			Address:    address.Bytes(),
 			SlotID:     *s4SetSlotId,
 			Version:    *s4SetVersion,
-			Payload:    []byte(*s4SetPayload),
+			Payload:    s4SetPayload,
 			Expiration: time.Now().UnixMilli() + *s4SetExpirationPeriod,
 		}
 		signature, err := envelope.Sign(key)
@@ -70,7 +80,7 @@ func main() {
 			SlotID:     envelope.SlotID,
 			Version:    envelope.Version,
 			Expiration: envelope.Expiration,
-			Payload:    []byte(*s4SetPayload),
+			Payload:    s4SetPayload,
 			Signature:  signature,
 		}
 
@@ -131,7 +141,12 @@ func main() {
 			return
 		}
 
-		fmt.Println(string(body))
+		var prettyJSON bytes.Buffer
+		if err := json.Indent(&prettyJSON, body, "", "  "); err != nil {
+			fmt.Println(string(body))
+		} else {
+			fmt.Println(prettyJSON.String())
+		}
 	}
 
 	sendRequest()