[Release-1.29] - Agent loadbalancer may deadlock when servers are removed

[brandond]

Backport fix for Agent loadbalancer may deadlock when servers are removed

• Agent loadbalancer may deadlock when servers are removed #6208

[aganesh-suse]

sorry posted k3s results here and closed by mistake. hence re-opening (deleted the k3s results). will update with rke2 results and close next week.

[aganesh-suse]

Validated on release-1.29 branch with version v1.29.7-rc4+rke2r1

Environment Details

Infrastructure

• Cloud
• Hosted

Node(s) CPU architecture, OS, and Version:

$ cat /etc/os-release
PRETTY_NAME="Ubuntu 22.04.2 LTS"

$ uname -m
x86_64

Cluster Configuration:

HA : 3 server / 1 agent

Config.yaml:

token: xxxx
write-kubeconfig-mode: "0644"
node-external-ip: 1.1.1.1

Testing Steps

1. Copy config.yaml

$ sudo mkdir -p /etc/rancher/rke2 && sudo cp config.yaml /etc/rancher/rke2

2. Install RKE2

curl -sfL https://get.rke2.io | sudo INSTALL_RKE2_VERSION='v1.29.7-rc4+rke2r1' INSTALL_RKE2_TYPE='server' INSTALL_RKE2_METHOD=tar sh -

3. Start the RKE2 service

$ sudo systemctl enable --now rke2-server
or 
$ sudo systemctl enable --now rke2-agent

4. Verify Cluster Status:

kubectl get nodes -o wide
kubectl get pods -A

5. Refer to verification steps here: Fix loadbalancer reentrant rlock k3s-io/k3s#10511
   Identify the server that the agent is connected to : netstat -na | grep 6443
   Disconnect the network on that server: ip link set dev eth0 down (or whatever interface that node is using)

The failed server should get removed from the load balancer server list

Replication Results:

• rke2 version used for replication:

$ rke2 -v
rke2 version v1.29.6+rke2r1 (21ad86ff88b85ea8c470a901fec0d6dbcf681ab3)
go version go1.21.11 X:boringcrypto

 level=info msg="Closing 1 connections to load balancer server <ip1>:6443"
 level=info msg="Connecting to proxy" url="wss://<ip1>:9345/v1-rke2/connect"
 level=error msg="Failed to connect to proxy. Empty dialer response" error="dial tcp <ip1>:9345: connect: connection refused"
 level=error msg="Remotedialer proxy error; reconnecting..." error="dial tcp <ip1>:9345: connect: connection refused" url="wss://<ip1>:9345/v1-rke2/connect"
.
.
level=info msg="Removing server from load balancer rke2-api-server-agent-load-balancer: <ip1>:6443"
level=info msg="Updated load balancer rke2-api-server-agent-load-balancer server addresses -> [<ip2>:6443 <ip3>:6443] [default: <ip1>:6443]"
level=info msg="Removing server from load balancer rke2-agent-load-balancer: <ip1>:9345"
level=info msg="Updated load balancer rke2-agent-load-balancer server addresses -> [<ip2>:9345 <ip3>:9345] [default: <ip1>:9345]"
level=info msg="Stopped tunnel to <ip1>:9345"

Validation Results:

• rke2 version used for validation:

$ rke2 -v
rke2 version v1.29.7-rc4+rke2r1 (94475ee48c61cec3e7638ccbec4fd60f548b80d9)
go version go1.22.5 X:boringcrypto

level=error msg="Remotedialer proxy error; reconnecting..." error="websocket: close 1006 (abnormal closure): unexpected EOF" url="wss://<ip1>:9345/v1-rke2/connect"
level=info msg="Closing 1 connections to load balancer server <ip1>:6443"
level=info msg="Connecting to proxy" url="wss://<ip1>:9345/v1-rke2/connect"
level=error msg="Failed to connect to proxy. Empty dialer response" error="dial tcp <ip1>:9345: connect: connection refused"
.
.
level=info msg="Removing server from load balancer rke2-api-server-agent-load-balancer: <ip1>:6443"
level=info msg="Updated load balancer rke2-api-server-agent-load-balancer server addresses -> [<ip2>:6443 <ip3>:6443] [default: <ip1>:6443]"
level=info msg="Removing server from load balancer rke2-agent-load-balancer: <ip1>:9345"
level=info msg="Updated load balancer rke2-agent-load-balancer server addresses -> [<ip2>:9345 <ip3>:9345] [default: <ip1>:9345]"
level=info msg="Stopped tunnel to <ip1>:9345"