fix: overwrite kernel args from --extra-agent-kernel-args

This allows to override default options (e.g. `console=ttyS0`) with
provided values. Make sure that full value is given for each option, as
any default values for the option are dropped if specified in
`--extra-agent-kernel-args`, e.g.
`--extra-agent-kernel-args=console=ttyS1`.

Fixes siderolabs#251

Signed-off-by: Andrey Smirnov <smirnov.andrey@gmail.com>

app/metal-controller-manager/internal/ipxe/ipxe_server.go

@@ -23,6 +23,8 @@ import (
 	"sigs.k8s.io/cluster-api/util/patch"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 
+	"github.com/talos-systems/go-procfs/procfs"
+
 	infrav1 "github.com/talos-systems/sidero/app/cluster-api-provider-sidero/api/v1alpha3"
 	metalv1alpha1 "github.com/talos-systems/sidero/app/metal-controller-manager/api/v1alpha1"
 	"github.com/talos-systems/sidero/app/metal-controller-manager/internal/server"
@@ -289,15 +291,21 @@ func newAgentEnvironment() *metalv1alpha1.Environment {
 		fmt.Sprintf("%s=%s:%s", constants.AgentEndpointArg, apiEndpoint, server.Port),
 	}
 
-	args = append(args, extraAgentKernelArgs...)
+	cmdline := procfs.NewCmdline(strings.Join(args, " "))
+	extra := procfs.NewCmdline(strings.Join(extraAgentKernelArgs, " "))
+
+	// override defaults with extra kernel agent params
+	for _, p := range extra.Parameters {
+		cmdline.Set(p.Key(), p)
+	}
 
 	env := &metalv1alpha1.Environment{
 		ObjectMeta: metav1.ObjectMeta{
 			Name: "agent",
 		},
 		Spec: metalv1alpha1.EnvironmentSpec{
 			Kernel: metalv1alpha1.Kernel{
-				Args: args,
+				Args: cmdline.Strings(),
 			},
 		},
 	}