feat: extend startup domain to Linux

This adds the ability for Linux hosts to join MS Active Directory domains using the realmd package.

Some light refactoring of when/where we check for the startup app to do it once before all hosts.

src/go/app/startup.go

@@ -99,6 +99,15 @@ func (this Startup) PreStart(ctx context.Context, exp *types.Experiment) error {
 			continue
 		}
 
+		// Check to see if a scenario exists for this experiment and if it
+		// contains a "startup" app. If so, store it for later use
+		var startupApp ifaces.ScenarioApp
+		for _, app := range exp.Apps() {
+			if app.Name() == "startup" {
+				startupApp = app
+			}
+		}
+
 		switch strings.ToLower(node.Hardware().OSType()) {
 		case "linux", "rhel", "centos":
 			var (
@@ -138,6 +147,26 @@ func (this Startup) PreStart(ctx context.Context, exp *types.Experiment) error {
 			if err := tmpl.CreateFileFromTemplate("linux_interfaces.tmpl", node, ifaceFile); err != nil {
 				return fmt.Errorf("generating linux interfaces script: %w", err)
 			}
+
+			if startupApp != nil {
+				for _, host := range startupApp.Hosts() {
+					if host.Hostname() == node.General().Hostname() {
+
+						var domainFile = startupDir + "/" + node.General().Hostname() + "-domain.sh"
+
+						node.AddInject(
+							domainFile,
+							"/etc/phenix/startup/4_domain-start.sh",
+							"0755", "",
+						)
+
+						if err := tmpl.CreateFileFromTemplate("linux_domain.tmpl", host.Metadata(), domainFile); err != nil {
+							return fmt.Errorf("generating linux domain script: %w", err)
+						}
+					}
+				}
+			}
+
 		case "windows":
 			startupFile := startupDir + "/" + node.General().Hostname() + "-startup.ps1"
 
@@ -178,15 +207,12 @@ func (this Startup) PreStart(ctx context.Context, exp *types.Experiment) error {
 				Metadata: make(map[string]interface{}),
 			}
 
-			// Check to see if a scenario exists for this experiment and if it
-			// contains a "startup" app. If so, see if this node has a metadata entry
+			// If startup app exists, see if this node has a metadata entry
 			// in the scenario app configuration.
-			for _, app := range exp.Apps() {
-				if app.Name() == "startup" {
-					for _, host := range app.Hosts() {
-						if host.Hostname() == node.General().Hostname() {
-							data.Metadata = host.Metadata()
-						}
+			if startupApp != nil {
+				for _, host := range startupApp.Hosts() {
+					if host.Hostname() == node.General().Hostname() {
+						data.Metadata = host.Metadata()
 					}
 				}
 			}

src/go/tmpl/templates/linux_domain.tmpl

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo "{{ .domain_controller.password }}" | realm join --user={{ .domain_controller.username }} {{ .domain_controller.domain }}