MetalLB frr-k8s - BFD cannot be enabled on a BGP Peer that already has route learning configured
### Summary
MetalLB frr-k8s - BFD cannot be enabled on a BGP Peer that already has route learning configured.
It works fine when configuring both route learning and BFD in the same step, but if route learning is configured first and in the next step the user wants to enable BFD, it will fail with error:
```
Helm upgrade failed for release metallb-system/metallb-resources with
chart metallb-resources@0.1.0+180d70083b3e: cannot patch \"extra-bgp-conf-ext-router1-b2213295\"
with kind FRRConfiguration: admission webhook \"frrconfigurationsvalidationwebhook.metallb.io\"
denied the request: multiple bfd profiles specified for neighbor 172.20.219.241
at vrf \nresource is invalid for node management-cluster-cp-2276d825a3-5t5f
```
### Steps to reproduce
Deploy a cluster with metallb values:
```yaml
metallb:
bgp_lbs:
l3_options:
bgp_peers:
ext-router1:
local_asn: 64513
peer_asn: 64512
peer_address: 172.20.219.241
password: XXXXXXXXX
advertised_pools:
- pool1
receive_routes:
mode: all
address_pools:
pool1:
addresses:
- 192.168.1.1-192.168.1.2
```
This will automatically enable frr-k8s mode for MetalLB since `receive_routes` is mentioned as implemented in [issue](https://gitlab.com/sylva-projects/sylva-core/-/issues/2352).
After deployment is completed, enable BFD on the BGP peer and run apply.sh:
```yaml
metallb:
bgp_lbs:
l3_options:
bfd_profiles:
bfd-profile-bgp:
receiveInterval: 1000
transmitInterval: 1000
detectMultiplier: 3
bgp_peers:
ext-router1:
local_asn: 64513
peer_asn: 64512
peer_address: 172.20.219.241
password: XXXXXXXXX
bfd_profile: bfd-profile-bgp
advertised_pools:
- pool1
receive_routes:
mode: all
address_pools:
pool1:
addresses:
- 192.168.1.1-192.168.1.2
```
### What is the current *bug* behavior?
Helm upgrade fails, metallb-resources HelmRelease has Failed state.
```shell
$ k get hr metallb-resources
NAME AGE READY STATUS
metallb-resources 18h False Helm upgrade failed for release metallb-system/metallb-resources with chart metallb-resources@0.1.0+180d70083b3e: cannot patch "extra-bgp-conf-ext-router1-b2213295" with kind FRRConfiguration: admission webhook "frrconfigurationsvalidationwebhook.metallb.io" denied the request: multiple bfd profiles specified for neighbor 172.20.219.241 at vrf ...
```
### What is the expected *correct* behavior?
BFD config can be added without errors.
### Relevant logs and/or screenshots
Seems linked to frr-k8s code for merging frrconfigurations:
https://github.com/metallb/frr-k8s/blob/main/internal/controller/merge.go#L247
Outputs from a working setup when BFD and route learning were enabled in the same step:
```shell
$ helm get all metallb-resources
NAME: metallb-resources
LAST DEPLOYED: Wed Dec 17 08:01:06 2025
NAMESPACE: metallb-system
STATUS: deployed
REVISION: 1
CHART: metallb-resources
VERSION: 0.1.0+180d70083b3e
APP_VERSION: 0.1.0
TEST SUITE: None
USER-SUPPLIED VALUES:
bgp_lbs:
address_pools:
pool1:
addresses:
- 192.168.1.1-192.168.1.2
l3_options:
bfd_profiles:
bfd-profile-bgp:
detectMultiplier: 3
receiveInterval: 1000
transmitInterval: 1000
bgp_peers:
ext-router1:
advertised_pools:
- pool1
bfd_profile: bfd-profile-bgp
local_asn: 64513
password: XXXXXXXXX
peer_address: 172.20.219.241
peer_asn: 64512
receive_routes:
mode: all
cluster_virtual_ip: 172.20.219.240
l2_lbs:
l2_options:
advertisements:
l2advertisement:
advertised_pools:
- lbpool
interfaces: []
node_selectors:
- matchLabels:
node-role.kubernetes.io/control-plane: "true"
COMPUTED VALUES:
bgp_lbs:
address_pools:
pool1:
addresses:
- 192.168.1.1-192.168.1.2
l3_options:
bfd_profiles:
bfd-profile-bgp:
detectMultiplier: 3
receiveInterval: 1000
transmitInterval: 1000
bgp_peers:
ext-router1:
advertised_pools:
- pool1
bfd_profile: bfd-profile-bgp
local_asn: 64513
password: XXXXXXXXX
peer_address: 172.20.219.241
peer_asn: 64512
receive_routes:
mode: all
cluster_virtual_ip: 172.20.219.240
l2_lbs:
l2_options:
advertisements:
l2advertisement:
advertised_pools:
- lbpool
interfaces: []
node_selectors:
- matchLabels:
node-role.kubernetes.io/control-plane: "true"
HOOKS:
MANIFEST:
apiVersion: v1
data:
password: TzRBY1huaHZJcjVa
kind: Secret
metadata:
labels:
app.kubernetes.io/instance: metallb-resources
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: metallb-resources
app.kubernetes.io/version: 0.1.0
helm.sh/chart: metallb-resources-0.1.0_180d70083b3e
helm.toolkit.fluxcd.io/name: metallb-resources
helm.toolkit.fluxcd.io/namespace: sylva-system
name: bgppeer-ext-router1-pass
namespace: metallb-system
type: kubernetes.io/basic-auth
---
apiVersion: metallb.io/v1beta1
kind: BFDProfile
metadata:
labels:
app.kubernetes.io/instance: metallb-resources
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: metallb-resources
app.kubernetes.io/version: 0.1.0
helm.sh/chart: metallb-resources-0.1.0_180d70083b3e
helm.toolkit.fluxcd.io/name: metallb-resources
helm.toolkit.fluxcd.io/namespace: sylva-system
name: bfd-profile-bgp
namespace: metallb-system
spec:
detectMultiplier: 3
receiveInterval: 1000
transmitInterval: 1000
---
apiVersion: metallb.io/v1beta1
kind: BGPAdvertisement
metadata:
labels:
app.kubernetes.io/instance: metallb-resources
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: metallb-resources
app.kubernetes.io/version: 0.1.0
helm.sh/chart: metallb-resources-0.1.0_180d70083b3e
helm.toolkit.fluxcd.io/name: metallb-resources
helm.toolkit.fluxcd.io/namespace: sylva-system
name: ext-router1
namespace: metallb-system
spec:
ipAddressPools:
- pool1
peers:
- ext-router1
---
apiVersion: metallb.io/v1beta2
kind: BGPPeer
metadata:
labels:
app.kubernetes.io/instance: metallb-resources
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: metallb-resources
app.kubernetes.io/version: 0.1.0
helm.sh/chart: metallb-resources-0.1.0_180d70083b3e
helm.toolkit.fluxcd.io/name: metallb-resources
helm.toolkit.fluxcd.io/namespace: sylva-system
name: ext-router1
namespace: metallb-system
spec:
bfdProfile: bfd-profile-bgp
myASN: 64513
passwordSecret:
name: bgppeer-ext-router1-pass
peerASN: 64512
peerAddress: 172.20.219.241
---
apiVersion: frrk8s.metallb.io/v1beta1
kind: FRRConfiguration
metadata:
labels:
app.kubernetes.io/instance: metallb-resources
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: metallb-resources
app.kubernetes.io/version: 0.1.0
helm.sh/chart: metallb-resources-0.1.0_180d70083b3e
helm.toolkit.fluxcd.io/name: metallb-resources
helm.toolkit.fluxcd.io/namespace: sylva-system
name: extra-bgp-conf-ext-router1-b2213295
namespace: metallb-system
spec:
bgp:
bfdProfiles:
- detectMultiplier: 3
name: bfd-profile-bgp
receiveInterval: 1000
transmitInterval: 1000
routers:
- asn: 64513
neighbors:
- address: 172.20.219.241
asn: 64512
bfdProfile: bfd-profile-bgp
passwordSecret:
name: bgppeer-ext-router1-pass
toReceive:
allowed:
mode: all
---
apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
labels:
app.kubernetes.io/instance: metallb-resources
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: metallb-resources
app.kubernetes.io/version: 0.1.0
helm.sh/chart: metallb-resources-0.1.0_180d70083b3e
helm.toolkit.fluxcd.io/name: metallb-resources
helm.toolkit.fluxcd.io/namespace: sylva-system
name: pool1
namespace: metallb-system
spec:
addresses:
- 192.168.1.1-192.168.1.2
---
apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
annotations:
helm.sh/resource-policy: keep
labels:
app.kubernetes.io/instance: metallb-resources
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: metallb-resources
app.kubernetes.io/version: 0.1.0
helm.sh/chart: metallb-resources-0.1.0_180d70083b3e
helm.toolkit.fluxcd.io/name: metallb-resources
helm.toolkit.fluxcd.io/namespace: sylva-system
name: lbpool
namespace: metallb-system
spec:
addresses:
- 172.20.219.240/32
---
apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
annotations:
helm.sh/resource-policy: keep
labels:
app.kubernetes.io/instance: metallb-resources
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: metallb-resources
app.kubernetes.io/version: 0.1.0
helm.sh/chart: metallb-resources-0.1.0_180d70083b3e
helm.toolkit.fluxcd.io/name: metallb-resources
helm.toolkit.fluxcd.io/namespace: sylva-system
name: l2advertisement
namespace: metallb-system
spec:
ipAddressPools:
- lbpool
nodeSelectors:
- matchLabels:
node-role.kubernetes.io/control-plane: "true"
$ k get frrconfigurations -n metallb-system
NAME AGE
extra-bgp-conf-ext-router1-b2213295 88m
metallb-management-cluster-cp-6bf4d88f08-6qw6z 85m
metallb-management-cluster-cp-6bf4d88f08-mwzzw 83m
metallb-management-cluster-cp-6bf4d88f08-wk58j 88m
$ k get frrconfigurations -n metallb-system extra-bgp-conf-ext-router1-b2213295 -o yaml
apiVersion: frrk8s.metallb.io/v1beta1
kind: FRRConfiguration
metadata:
annotations:
meta.helm.sh/release-name: metallb-resources
meta.helm.sh/release-namespace: metallb-system
creationTimestamp: "2025-12-17T07:52:43Z"
generation: 1
labels:
app.kubernetes.io/instance: metallb-resources
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/name: metallb-resources
app.kubernetes.io/version: 0.1.0
helm.sh/chart: metallb-resources-0.1.0_180d70083b3e
helm.toolkit.fluxcd.io/name: metallb-resources
helm.toolkit.fluxcd.io/namespace: sylva-system
name: extra-bgp-conf-ext-router1-b2213295
namespace: metallb-system
resourceVersion: "11681"
uid: 5fd048b3-a37d-4e13-a03f-3fdd1106611e
spec:
bgp:
bfdProfiles:
- detectMultiplier: 3
name: bfd-profile-bgp
receiveInterval: 1000
transmitInterval: 1000
routers:
- asn: 64513
neighbors:
- address: 172.20.219.241
asn: 64512
bfdProfile: bfd-profile-bgp
disableMP: false
dualStackAddressFamily: false
passwordSecret:
name: bgppeer-ext-router1-pass
toReceive:
allowed:
mode: all
$ k get frrconfigurations -n metallb-system metallb-management-cluster-cp-6bf4d88f08-6qw6z -o yaml
apiVersion: frrk8s.metallb.io/v1beta1
kind: FRRConfiguration
metadata:
creationTimestamp: "2025-12-17T07:55:52Z"
generation: 1
name: metallb-management-cluster-cp-6bf4d88f08-6qw6z
namespace: metallb-system
resourceVersion: "2726"
uid: f3619871-b10f-48d7-8857-11252cad8509
spec:
bgp:
bfdProfiles:
- detectMultiplier: 3
echoMode: false
name: bfd-profile-bgp
passiveMode: false
receiveInterval: 1000
transmitInterval: 1000
routers:
- asn: 64513
neighbors:
- address: 172.20.219.241
asn: 64512
bfdProfile: bfd-profile-bgp
disableMP: false
dualStackAddressFamily: false
passwordSecret:
name: bgppeer-ext-router1-pass
port: 179
toAdvertise:
allowed:
mode: filtered
toReceive:
allowed:
mode: filtered
nodeSelector:
matchLabels:
kubernetes.io/hostname: management-cluster-cp-6bf4d88f08-6qw6z
raw: {}
$ k get frrnodestates
NAME AGE
management-cluster-cp-6bf4d88f08-6qw6z 85m
management-cluster-cp-6bf4d88f08-mwzzw 83m
management-cluster-cp-6bf4d88f08-wk58j 89m
$ k get frrnodestates management-cluster-cp-6bf4d88f08-6qw6z
NAME AGE
management-cluster-cp-6bf4d88f08-6qw6z 85m
$ k get frrnodestates management-cluster-cp-6bf4d88f08-6qw6z -o yaml
apiVersion: frrk8s.metallb.io/v1beta1
kind: FRRNodeState
metadata:
creationTimestamp: "2025-12-17T07:55:59Z"
generation: 1
name: management-cluster-cp-6bf4d88f08-6qw6z
resourceVersion: "3183"
uid: 257113d6-f3c4-49bc-bfa3-84074493b096
spec: {}
status:
lastConversionResult: success
lastReloadResult: success
runningConfig: |
Building configuration...
Current configuration:
!
frr version 10.4.1_git
frr defaults traditional
hostname management-cluster-cp-6bf4d88f08-6qw6z
log file /etc/frr/frr.log informational
log timestamp precision 3
service integrated-vtysh-config
!
ip prefix-list 172.20.219.241-allowed-ipv4 seq 1 deny any
ip prefix-list 172.20.219.241-inpl-ipv4 seq 1 permit any
!
ipv6 prefix-list 172.20.219.241-allowed-ipv6 seq 1 deny any
ipv6 prefix-list 172.20.219.241-inpl-ipv4 seq 2 permit any
!
route-map 172.20.219.241-out permit 1
match ip address prefix-list 172.20.219.241-allowed-ipv4
exit
!
route-map 172.20.219.241-out permit 2
match ipv6 address prefix-list 172.20.219.241-allowed-ipv6
exit
!
route-map 172.20.219.241-in permit 3
match ip address prefix-list 172.20.219.241-inpl-ipv4
exit
!
route-map 172.20.219.241-in permit 4
match ipv6 address prefix-list 172.20.219.241-inpl-ipv4
exit
!
router bgp 64513
no bgp ebgp-requires-policy
no bgp enforce-first-as
no bgp hard-administrative-reset
no bgp default ipv4-unicast
no bgp graceful-restart notification
bgp graceful-restart preserve-fw-state
no bgp network import-check
neighbor 172.20.219.241 remote-as 64512
neighbor 172.20.219.241 bfd
neighbor 172.20.219.241 bfd profile bfd-profile-bgp
neighbor 172.20.219.241 password <retracted>
!
address-family ipv4 unicast
neighbor 172.20.219.241 activate
neighbor 172.20.219.241 route-map 172.20.219.241-in in
neighbor 172.20.219.241 route-map 172.20.219.241-out out
exit-address-family
exit
!
bfd
profile bfd-profile-bgp
transmit-interval 1000
receive-interval 1000
exit
!
exit
!
end
```
### Possible fixes
None identified for now.
issue
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