Detect if community based drop mechanism is used and act accordingly

pkg/frr/configure.go

@@ -69,6 +69,8 @@ func (m *Manager) Configure(in Configuration, nm *nl.Manager, nwopCfg *config.Co
 	targetConfig = fixRouteTargetReload(targetConfig)
 	targetConfig = applyCfgReplacements(targetConfig, nwopCfg.Replacements)
 
+	in.HasCommunityDrop = m.hasCommunityDrop
+
 	if !bytes.Equal(currentConfig, targetConfig) {
 		err = os.WriteFile(m.ConfigPath, targetConfig, frrPermissions)
 		if err != nil {
@@ -99,27 +101,27 @@ func (m *Manager) renderSubtemplates(in Configuration, nlManager *nl.Manager) (*
 		return nil, fmt.Errorf("error getting node's name")
 	}
 
-	vrfs, err := render(vrfTpl, in.VRFs)
+	vrfs, err := render(vrfTpl, in)
 	if err != nil {
 		return nil, err
 	}
-	neighbors, err := render(neighborTpl, in.VRFs)
+	neighbors, err := render(neighborTpl, in)
 	if err != nil {
 		return nil, err
 	}
-	neighborsV4, err := render(neighborV4Tpl, in.VRFs)
+	neighborsV4, err := render(neighborV4Tpl, in)
 	if err != nil {
 		return nil, err
 	}
-	neighborsV6, err := render(neighborV6Tpl, in.VRFs)
+	neighborsV6, err := render(neighborV6Tpl, in)
 	if err != nil {
 		return nil, err
 	}
-	prefixlists, err := render(prefixListTpl, in.VRFs)
+	prefixlists, err := render(prefixListTpl, in)
 	if err != nil {
 		return nil, err
 	}
-	routemaps, err := render(routeMapTpl, in.VRFs)
+	routemaps, err := render(routeMapTpl, in)
 	if err != nil {
 		return nil, err
 	}

pkg/frr/manager.go

@@ -26,6 +26,7 @@ type Manager struct {
 	ipv4MgmtRouteMapIn *string
 	ipv6MgmtRouteMapIn *string
 	mgmtVrf            string
+	hasCommunityDrop   bool
 
 	ConfigPath   string
 	TemplatePath string
@@ -61,8 +62,9 @@ type VRFConfiguration struct {
 }
 
 type Configuration struct {
-	ASN  int
-	VRFs []VRFConfiguration
+	ASN              int
+	VRFs             []VRFConfiguration
+	HasCommunityDrop bool
 }
 
 func NewFRRManager() *Manager {
@@ -105,6 +107,12 @@ func (m *Manager) Init(mgmtVrf string) error {
 	}
 	m.ipv6MgmtRouteMapIn = routeMap
 
+	communityDrop, err := hasCommunityDrop(m.ConfigPath)
+	if err != nil {
+		return fmt.Errorf("error checking for community drop in FRR config: %w", err)
+	}
+	m.hasCommunityDrop = communityDrop
+
 	return nil
 }
 

pkg/frr/templates.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"os"
 	"regexp"
+	"strings"
 	"text/template"
 )
 
@@ -103,6 +104,15 @@ func getRouteMapName(file, addressFamily, mgmtVrfName string) (*string, error) {
 	return &matches[1], nil
 }
 
+func hasCommunityDrop(file string) (bool, error) {
+	fileContent, err := os.ReadFile(file)
+	if err != nil {
+		return false, fmt.Errorf("error reading frr config file %s: %w", file, err)
+	}
+	content := string(fileContent)
+	return strings.Contains(content, "cm-received-fabric"), nil
+}
+
 func generateTemplateConfig(tplFile, original string) error {
 	fileContent, err := os.ReadFile(original)
 	if err != nil {

pkg/frr/tpl/bgp-neighbor-v4.tpl

@@ -1,4 +1,4 @@
-{{range $vrf := .}}
+{{range $vrf := .VRFs}}
 {{if and $vrf.ShouldTemplateVRF (not $vrf.IsTaaS)}}
   neighbor dv.{{$vrf.Name}} activate
   neighbor dv.{{$vrf.Name}} allowas-in origin

pkg/frr/tpl/bgp-neighbor-v6.tpl

@@ -1,4 +1,4 @@
-{{range $vrf := .}}
+{{range $vrf := .VRFs}}
 {{if and $vrf.ShouldTemplateVRF (not $vrf.IsTaaS)}}
   neighbor dv.{{$vrf.Name}} activate
   neighbor dv.{{$vrf.Name}} allowas-in origin

pkg/frr/tpl/bgp-neighbor.tpl

@@ -1,4 +1,4 @@
-{{range $vrf := .}}
+{{range $vrf := .VRFs}}
 {{if and $vrf.ShouldTemplateVRF (not $vrf.IsTaaS)}}
  neighbor dv.{{$vrf.Name}} interface remote-as internal
 {{end}}

pkg/frr/tpl/prefix-list.tpl

@@ -1,4 +1,4 @@
-{{range $vrf := .}}
+{{range $vrf := .VRFs}}
 {{if not $vrf.IsTaaS}}
 {{range $i, $pl := $vrf.Import}}
 {{range $item := $pl.Items}}

pkg/frr/tpl/route-map.tpl

@@ -1,4 +1,4 @@
-{{range $vrf := .}}
+{{range $vrf := .VRFs}}
 {{if not $vrf.IsTaaS}}
 {{range $i, $pl := $vrf.Import}}
 route-map rm_{{$vrf.Name}}_import {{if $vrf.ShouldTemplateVRF}}permit{{else}}deny{{end}} {{$pl.Seq}}
@@ -10,11 +10,19 @@ exit
 {{- end}}
 
 route-map rm_{{$vrf.Name}}_export deny 1
+{{if $.HasCommunityDrop}}
+  match community cm-received-fabric
+{{else}}
   match tag 20000
+{{- end}}
 exit
 
 route-map rm6_{{$vrf.Name}}_export deny 1
+{{if $.HasCommunityDrop}}
+  match community cm-received-fabric
+{{else}}
   match tag 20000
+{{- end}}
 exit
 
 {{range $i, $pl := $vrf.Export}}

pkg/frr/tpl/vrf.tpl

@@ -1,4 +1,4 @@
-{{range $vrf := .}}
+{{range $vrf := .VRFs}}
 {{if and $vrf.ShouldTemplateVRF (not $vrf.IsTaaS)}}
 vrf vr.{{$vrf.Name}}
  vni {{$vrf.VNI}}