Implement new configuration strategy for OOB plugin

README.md

@@ -62,11 +62,16 @@ prefixDelegation:
 - can be used standalone or (in combination with the `ipam` plugin) in kubernetes
 
 ## OOB
-The OOB plugin leases an IP object to an out-of-band client, based on a subnet detection. The plugin is an equivalent of the metal+ipam kombination, meant to be used in IronCore's out-of-band network.
+The OOB plugin leases an IP address to an out-of-band client, based on a subnet detection. For each a corresponding IPAM IP object is created. Thus, the plugin is an equivalent of the onmetal+ipam combination, though it is meant to be used in IronCore's out-of-band network.
 
-An IP object with a random IP address from the subnet's vacant list is created in IPAM, the IP address is then leased back to the client. Currently no cleanup-on-release is performed, so clients with stable identifiers are guaranteed to become stable IP addresses.
+An IP object with a random IP address from the subnet's vacant list is created in IPAM, the IP address is then leased back to the client. Currently, no cleanup-on-release is performed, so clients with stable identifiers are guaranteed to become stable IP addresses.
 ### Configuration
 As for in-band, a kubernetes namespace shall be passed as a parameter. Further, a subnet label list in the form `value:key` shall be passed, it is used for subnet detection.
+Providing those in `oob_config.yaml` goes as follows:
+```yaml
+namespace: oob-ns
+subnetLabel: subnet=dhcp
+```
 ### Notes
 - supports both IPv4 and IPv6
 - IPv6 relays are supported, IPv4 are not

example/oob_config.yaml

@@ -0,0 +1,2 @@
+namespace: oob-ns
+subnetLabel: subnet=dhcp

internal/api/oob_config.go

@@ -0,0 +1,9 @@
+// SPDX-FileCopyrightText: 2024 SAP SE or an SAP affiliate company and IronCore contributors
+// SPDX-License-Identifier: MIT
+
+package api
+
+type OOBConfig struct {
+	Namespace   string `yaml:"namespace"`
+	SubnetLabel string `yaml:"subnetLabel"`
+}

plugins/oob/plugin.go

@@ -6,8 +6,13 @@ package oob
 import (
 	"fmt"
 	"net"
+	"os"
+	"strings"
 	"time"
 
+	"github.com/ironcore-dev/fedhcp/internal/api"
+	"gopkg.in/yaml.v3"
+
 	ipamv1alpha1 "github.com/ironcore-dev/ipam/api/ipam/v1alpha1"
 
 	"github.com/coredhcp/coredhcp/handler"
@@ -35,24 +40,45 @@ const (
 	UNKNOWN_IP = "0.0.0.0"
 )
 
-func parseArgs(args ...string) (string, string, error) {
-	if len(args) < 2 {
-		return "", "", fmt.Errorf("at least two arguments must be passed to ipam plugin, a namespace and a "+
-			"OOB subnet label, got %d", len(args))
+// args[0] = path to config file
+func parseArgs(args ...string) (string, error) {
+	if len(args) != 1 {
+		return "", fmt.Errorf("exactly one argument must be passed to the metal plugin, got %d", len(args))
+	}
+	return args[0], nil
+}
+
+func loadConfig(args ...string) (*api.OOBConfig, error) {
+	path, err := parseArgs(args...)
+	if err != nil {
+		return nil, fmt.Errorf("invalid configuration: %v", err)
 	}
 
-	namespace := args[0]
-	oobLabel := args[1]
-	return namespace, oobLabel, nil
+	log.Debugf("Reading ipam config file %s", path)
+	configData, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read config file: %v", err)
+	}
+
+	config := &api.OOBConfig{}
+	if err = yaml.Unmarshal(configData, config); err != nil {
+		return nil, fmt.Errorf("failed to parse config file: %v", err)
+	}
+
+	// TODO remove after https://github.com/ironcore-dev/FeDHCP/issues/221 is implemented
+	if !strings.Contains(config.SubnetLabel, "=") {
+		return nil, fmt.Errorf("invalid subnet label: %s, should be 'key=value'", config.SubnetLabel)
+	}
+	return config, nil
 }
 
 func setup6(args ...string) (handler.Handler6, error) {
-	namespace, oobLabel, err := parseArgs(args...)
+	oobConfig, err := loadConfig(args...)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("invalid configuration: %v", err)
 	}
 
-	k8sClient, err = NewK8sClient(namespace, oobLabel)
+	k8sClient, err = NewK8sClient(oobConfig.Namespace, oobConfig.SubnetLabel)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create k8s client: %w", err)
 	}
@@ -117,12 +143,12 @@ func handler6(req, resp dhcpv6.DHCPv6) (dhcpv6.DHCPv6, bool) {
 }
 
 func setup4(args ...string) (handler.Handler4, error) {
-	namespace, oobLabel, err := parseArgs(args...)
+	oobConfig, err := loadConfig(args...)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("invalid configuration: %v", err)
 	}
 
-	k8sClient, err = NewK8sClient(namespace, oobLabel)
+	k8sClient, err = NewK8sClient(oobConfig.Namespace, oobConfig.SubnetLabel)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create k8s client: %w", err)
 	}