Add FRR config hot-replace feature

pkg/config/config.go

@@ -18,13 +18,21 @@ type Config struct {
 	BPFInterfaces []string             `yaml:"bpfInterfaces"`
 	SkipVRFConfig []string             `yaml:"skipVRFConfig"`
 	ServerASN     int                  `yaml:"serverASN"`
+
+	Replacements []Replacement `yaml:"replacements"`
 }
 
 type VRFConfig struct {
 	VNI int    `yaml:"vni"`
 	RT  string `yaml:"rt"`
 }
 
+type Replacement struct {
+	Old   string `yaml:"old"`
+	New   string `yaml:"new"`
+	Regex bool   `yaml:"regex"`
+}
+
 func LoadConfig() (*Config, error) {
 	config := &Config{}
 

pkg/frr/configure.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"regexp"
 
+	"github.com/telekom/das-schiff-network-operator/pkg/config"
 	"github.com/telekom/das-schiff-network-operator/pkg/healthcheck"
 	"github.com/telekom/das-schiff-network-operator/pkg/nl"
 )
@@ -33,7 +34,7 @@ type templateConfig struct {
 	HostRouterID     string
 }
 
-func (m *Manager) Configure(in Configuration, nm *nl.Manager) (bool, error) {
+func (m *Manager) Configure(in Configuration, nm *nl.Manager, nwopCfg *config.Config) (bool, error) {
 	// Remove permit from VRF and only allow deny rules for mgmt VRFs
 	for i := range in.VRFs {
 		if in.VRFs[i].Name != m.mgmtVrf {
@@ -50,7 +51,7 @@ func (m *Manager) Configure(in Configuration, nm *nl.Manager) (bool, error) {
 		}
 	}
 
-	config, err := m.renderSubtemplates(in, nm)
+	frrConfig, err := m.renderSubtemplates(in, nm)
 	if err != nil {
 		return false, err
 	}
@@ -60,12 +61,13 @@ func (m *Manager) Configure(in Configuration, nm *nl.Manager) (bool, error) {
 		return false, fmt.Errorf("error reading configuration file: %w", err)
 	}
 
-	targetConfig, err := render(m.configTemplate, config)
+	targetConfig, err := render(m.configTemplate, frrConfig)
 	if err != nil {
 		return false, err
 	}
 
 	targetConfig = fixRouteTargetReload(targetConfig)
+	targetConfig = applyCfgReplacements(targetConfig, nwopCfg.Replacements)
 
 	if !bytes.Equal(currentConfig, targetConfig) {
 		err = os.WriteFile(m.ConfigPath, targetConfig, frrPermissions)
@@ -154,8 +156,8 @@ func (m *Manager) renderSubtemplates(in Configuration, nlManager *nl.Manager) (*
 
 // fixRouteTargetReload is a workaround for FRR's inability to reload route-targets if they are configured in a single line.
 // This function splits such lines into multiple lines, each containing a single route-target.
-func fixRouteTargetReload(config []byte) []byte {
-	return rtLinesRe.ReplaceAllFunc(config, func(s []byte) []byte {
+func fixRouteTargetReload(frrConfig []byte) []byte {
+	return rtLinesRe.ReplaceAllFunc(frrConfig, func(s []byte) []byte {
 		parts := rtPartsRe.FindSubmatch(s)
 		if parts == nil {
 			return s
@@ -172,3 +174,16 @@ func fixRouteTargetReload(config []byte) []byte {
 		return []byte(lines[:len(lines)-1])
 	})
 }
+
+// applyCfgReplacements replaces placeholders in the configuration with the actual values.
+func applyCfgReplacements(frrConfig []byte, replacements []config.Replacement) []byte {
+	for _, replacement := range replacements {
+		if !replacement.Regex {
+			frrConfig = bytes.ReplaceAll(frrConfig, []byte(replacement.Old), []byte(replacement.New))
+		} else {
+			re := regexp.MustCompile(replacement.Old)
+			frrConfig = re.ReplaceAll(frrConfig, []byte(replacement.New))
+		}
+	}
+	return frrConfig
+}

pkg/frr/frr_test.go

@@ -134,7 +134,7 @@ var _ = Describe("frr", func() {
 		It("return error if cannot get underlay IP", func() {
 			m := &Manager{}
 			nlMock.EXPECT().AddrList(gomock.Any(), gomock.Any()).Return(nil, errors.New("error listing addresses"))
-			_, err := m.Configure(Configuration{}, nl.NewManager(nlMock))
+			_, err := m.Configure(Configuration{}, nl.NewManager(nlMock), &config.Config{})
 			Expect(err).To(HaveOccurred())
 		})
 		It("return error if cannot node's name", func() {
@@ -148,7 +148,7 @@ var _ = Describe("frr", func() {
 			nlMock.EXPECT().AddrList(gomock.Any(), gomock.Any()).Return([]netlink.Addr{
 				{IPNet: netlink.NewIPNet(net.IPv4(0, 0, 0, 0))},
 			}, nil)
-			_, err := m.Configure(Configuration{}, nl.NewManager(nlMock))
+			_, err := m.Configure(Configuration{}, nl.NewManager(nlMock), &config.Config{})
 			Expect(err).To(HaveOccurred())
 
 			if isSet {
@@ -165,7 +165,7 @@ var _ = Describe("frr", func() {
 			nlMock.EXPECT().AddrList(gomock.Any(), gomock.Any()).Return([]netlink.Addr{
 				{IPNet: netlink.NewIPNet(net.IPv4(0, 0, 0, 0))},
 			}, nil)
-			_, err = m.Configure(Configuration{}, nl.NewManager(nlMock))
+			_, err = m.Configure(Configuration{}, nl.NewManager(nlMock), &config.Config{})
 			Expect(err).To(HaveOccurred())
 
 			if isSet {
@@ -189,7 +189,7 @@ var _ = Describe("frr", func() {
 			nlMock.EXPECT().AddrList(gomock.Any(), gomock.Any()).Return([]netlink.Addr{
 				{IPNet: netlink.NewIPNet(net.IPv4(0, 0, 0, 0))},
 			}, nil)
-			_, err = m.Configure(Configuration{}, nl.NewManager(nlMock))
+			_, err = m.Configure(Configuration{}, nl.NewManager(nlMock), &config.Config{})
 			Expect(err).To(HaveOccurred())
 
 			if isSet {

pkg/reconciler/layer3.go

@@ -100,7 +100,7 @@ func (r *reconcile) configureFRR(vrfConfigs []frr.VRFConfiguration, reloadTwice
 	changed, err := r.frrManager.Configure(frr.Configuration{
 		VRFs: vrfConfigs,
 		ASN:  r.config.ServerASN,
-	}, r.netlinkManager)
+	}, r.netlinkManager, r.config)
 	if err != nil {
 		r.Logger.Error(err, "error updating FRR configuration")
 		return fmt.Errorf("error updating FRR configuration: %w", err)