[relay] Feature/relay integration (#2244)

This update adds new relay integration for NetBird clients. The new relay is based on web sockets and listens on a single port.

- Adds new relay implementation with websocket with single port relaying mechanism
- refactor peer connection logic, allowing upgrade and downgrade from/to P2P connection
- peer connections are faster since it connects first to relay and then upgrades to P2P
- maintains compatibility with old clients by not using the new relay
- updates infrastructure scripts with new relay service

relay/cmd/env.go

@@ -0,0 +1,35 @@
+package cmd
+
+import (
+	"os"
+	"strings"
+
+	log "github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+	"github.com/spf13/pflag"
+)
+
+// setFlagsFromEnvVars reads and updates flag values from environment variables with prefix NB_
+func setFlagsFromEnvVars(cmd *cobra.Command) {
+	flags := cmd.PersistentFlags()
+	flags.VisitAll(func(f *pflag.Flag) {
+		newEnvVar := flagNameToEnvVar(f.Name, "NB_")
+		value, present := os.LookupEnv(newEnvVar)
+		if !present {
+			return
+		}
+
+		err := flags.Set(f.Name, value)
+		if err != nil {
+			log.Infof("unable to configure flag %s using variable %s, err: %v", f.Name, newEnvVar, err)
+		}
+	})
+}
+
+// flagNameToEnvVar converts flag name to environment var name adding a prefix,
+// replacing dashes and making all uppercase (e.g. setup-keys is converted to NB_SETUP_KEYS according to the input prefix)
+func flagNameToEnvVar(cmdFlag string, prefix string) string {
+	parsed := strings.ReplaceAll(cmdFlag, "-", "_")
+	upper := strings.ToUpper(parsed)
+	return prefix + upper
+}