nuageinit: implement bootcmd support

Add support for the 'bootcmd' cloud-config directive, which allows
running commands very early in the boot process, before the hostname
is set and before the network is configured.

- nuageinit: bootcmd() function follows the same pattern as runcmd(),
  writing commands to /var/cache/nuageinit/bootcmds instead of runcmds.
  It is the first entry in the pre_network_calls table.

- rc.d/nuageinit: execute /var/cache/nuageinit/bootcmds immediately
  after /usr/libexec/nuageinit completes, before unmounting the config
  drive. This ensures bootcmd runs before NETWORKING per cloud-init spec.

libexec/nuageinit/nuageinit

@@ -524,6 +524,23 @@ local function disable_root(obj)
 	end
 end
 
+local function bootcmd(obj)
+	if obj.bootcmd == nil then return end
+	local f = nil
+	for _, c in ipairs(obj.bootcmd) do
+		if f == nil then
+			nuage.mkdir_p(root .. "/var/cache/nuageinit")
+			f = assert(io.open(root .. "/var/cache/nuageinit/bootcmds", "w"))
+			f:write("#!/bin/sh\n")
+		end
+		f:write(c .. "\n")
+	end
+	if f ~= nil then
+		f:close()
+		nuage.chmod(root .. "/var/cache/nuageinit/bootcmds", "0755")
+	end
+end
+
 local function runcmd(obj)
 	if obj.runcmd == nil then return end
 	local f = nil
@@ -794,6 +811,7 @@ if line == nil then
 --  YAML user-data
 elseif line == "#cloud-config" then
 	local pre_network_calls = {
+		bootcmd,
 		sethostname,
 		settimezone,
 		groups,

libexec/nuageinit/nuageinit.7

@@ -362,6 +362,9 @@ does not automatically install them.
 Ensure the relevant command is listed in your
 .Nm packages
 section.
+.It Ic bootcmd
+An array of commands to be run early in the boot process,
+before the hostname is set and before the network is configured.
 .It Ic chpasswd
 Change the passwords for users, it accepts the following keys:
 .Bl -tag -width "expire"
@@ -424,6 +427,8 @@ Here is an example of a YAML configuration for
 .Nm :
 .Bd -literal
 #cloud-config
+bootcmd:
+  - kldload if_bridge
 fqdn: myhost.mynetwork.tld
 users:
   - default

libexec/rc/rc.d/nuageinit

@@ -89,6 +89,10 @@ nuageinit_start()
 		/usr/libexec/nuageinit /media/nuageinit $citype 2>&1 | tee -a /var/log/nuageinit.log
 		;;
 	esac
+	if [ -x /var/cache/nuageinit/bootcmds ]; then
+		echo "Executing 'bootcmd'" | tee -a /var/log/nuageinit.log
+		/var/cache/nuageinit/bootcmds 2>&1 | tee -a /var/log/nuageinit.log
+	fi
 	if [ -n "$drive" ]; then
 		umount /media/nuageinit
 		rmdir /media/nuageinit