Allow extra kernel args, set via cli flag: (#261)

## Description


This allows operators to set any necessary and needed kernel commandline args to the default installer; OSIE. This makes custom kernel args a first class option instead of the current model to overload the "facility" field in the backend data.

## Why is this needed



Fixes: #

## How Has This Been Tested?





## How are existing users impacted? What migration steps/scripts do we need?





## Checklist:

I have:

- [ ] updated the documentation and/or roadmap (if required)
- [ ] added unit or e2e tests
- [ ] provided instructions on how to upgrade

cmd/boots/main.go

@@ -79,6 +79,8 @@ type config struct {
 	syslogAddr string
 	// loglevel is the log level for boots
 	logLevel string
+	// extraKernelArgs are key=value pairs to be added as kernel commandline to the kernel in iPXE for OSIE
+	extraKernelArgs string
 }
 
 func main() {
@@ -205,7 +207,7 @@ func main() {
 	mainlog.With("addr", cfg.dhcpAddr).Info("serving dhcp")
 	go dhcpServer.ServeDHCP(cfg.dhcpAddr, nextServer, ipxeBaseURL, bootsBaseURL)
 	mainlog.With("addr", cfg.httpAddr).Info("serving http")
-	go httpServer.ServeHTTP(registerInstallers(), cfg.httpAddr, ipxePattern, ipxeHandler)
+	go httpServer.ServeHTTP(cfg.registerInstallers(), cfg.httpAddr, ipxePattern, ipxeHandler)
 
 	<-ctx.Done()
 	mainlog.Info("boots shutting down")
@@ -345,6 +347,7 @@ func newCLI(cfg *config, fs *flag.FlagSet) *ffcli.Command {
 	fs.StringVar(&cfg.logLevel, "log-level", "info", "log level.")
 	fs.StringVar(&cfg.dhcpAddr, "dhcp-addr", conf.BOOTPBind, "IP and port to listen on for DHCP.")
 	fs.StringVar(&cfg.syslogAddr, "syslog-addr", conf.SyslogBind, "IP and port to listen on for syslog messages.")
+	fs.StringVar(&cfg.extraKernelArgs, "extra-kernel-args", "", "Extra set of kernel args (k=v k=v) that are appended to the kernel cmdline when booting via iPXE.")
 
 	return &ffcli.Command{
 		Name:       name,
@@ -357,7 +360,7 @@ func newCLI(cfg *config, fs *flag.FlagSet) *ffcli.Command {
 	}
 }
 
-func registerInstallers() job.Installers {
+func (cf *config) registerInstallers() job.Installers {
 	// register installers
 	i := job.NewInstallers()
 	// register coreos/flatcar
@@ -375,7 +378,7 @@ func registerInstallers() job.Installers {
 	o := osie.Installer{}
 	i.RegisterDistro("discovery", o.Discover())
 	// register osie as default
-	d := osie.Installer{}
+	d := osie.Installer{ExtraKernelArgs: cf.extraKernelArgs}
 	i.RegisterDefaultInstaller(d.DefaultHandler())
 	// register rancher
 	r := rancher.Installer{}

cmd/boots/main_test.go

@@ -70,6 +70,7 @@ func TestCustomUsageFunc(t *testing.T) {
 
 FLAGS
   -dhcp-addr              IP and port to listen on for DHCP. (default "%v:67")
+  -extra-kernel-args      Extra set of kernel args (k=v k=v) that are appended to the kernel cmdline when booting via iPXE.
   -http-addr              local IP and port to listen on for the serving iPXE binaries and files via HTTP. (default "%[1]v:80")
   -ipxe-enable-http       enable serving iPXE binaries via HTTP. (default "true")
   -ipxe-enable-tftp       enable serving iPXE binaries via TFTP. (default "true")

installers/osie/main.go

@@ -10,7 +10,10 @@ import (
 	"go.opentelemetry.io/otel/trace"
 )
 
-type Installer struct{}
+type Installer struct {
+	// ExtraKernelArgs are key=value pairs to be added as kernel commandline to the kernel in iPXE for OSIE.
+	ExtraKernelArgs string
+}
 
 // DefaultHandler determines the ipxe boot script to be returned.
 // If the job has an instance with Rescue true, the rescue boot script is returned.
@@ -31,7 +34,7 @@ func (i Installer) rescue() job.BootScript {
 		s.Set("action", "rescue")
 		s.Set("state", j.HardwareState())
 
-		return bootScript(ctx, "rescue", j, s)
+		return i.bootScript(ctx, "rescue", j, s)
 	}
 }
 
@@ -50,7 +53,7 @@ func (i Installer) install() job.BootScript {
 		}
 		s.Set("state", j.HardwareState())
 
-		return bootScript(ctx, "install", j, s)
+		return i.bootScript(ctx, "install", j, s)
 	}
 }
 
@@ -59,18 +62,18 @@ func (i Installer) Discover() job.BootScript {
 		s.Set("action", "discover")
 		s.Set("state", j.HardwareState())
 
-		return bootScript(ctx, "discover", j, s)
+		return i.bootScript(ctx, "discover", j, s)
 	}
 }
 
-func bootScript(ctx context.Context, action string, j job.Job, s ipxe.Script) ipxe.Script {
+func (i Installer) bootScript(ctx context.Context, action string, j job.Job, s ipxe.Script) ipxe.Script {
 	s.Set("arch", j.Arch())
 	s.Set("parch", j.PArch())
 	s.Set("bootdevmac", j.PrimaryNIC().String())
 	s.Set("base-url", osieBaseURL(j))
 	s.Kernel("${base-url}/" + kernelPath(j))
 
-	ks := kernelParams(ctx, action, j.HardwareState(), j, s)
+	ks := i.kernelParams(ctx, action, j.HardwareState(), j, s)
 
 	ks.Initrd("${base-url}/" + initrdPath(j))
 
@@ -84,7 +87,7 @@ func bootScript(ctx context.Context, action string, j job.Job, s ipxe.Script) ip
 	return ks
 }
 
-func kernelParams(ctx context.Context, action, state string, j job.Job, s ipxe.Script) ipxe.Script {
+func (i Installer) kernelParams(ctx context.Context, action, state string, j job.Job, s ipxe.Script) ipxe.Script {
 	s.Args("ip=dhcp") // Dracut?
 	s.Args("modules=loop,squashfs,sd-mod,usb-storage")
 	s.Args("alpine_repo=" + alpineMirror(j))
@@ -96,6 +99,11 @@ func kernelParams(ctx context.Context, action, state string, j job.Job, s ipxe.S
 	s.Args("packet_state=${state}")
 	s.Args("osie_vendors_url=" + conf.OsieVendorServicesURL)
 
+	// Add extra kernel args
+	if i.ExtraKernelArgs != "" {
+		s.Args(i.ExtraKernelArgs)
+	}
+
 	// only add traceparent if tracing is enabled
 	if sc := trace.SpanContextFromContext(ctx); sc.IsSampled() {
 		// manually assemble a traceparent string because the "right" way is clunkier