add loadbalancer address allocator

This adds a simple controller that will watch for services of type LoadBalancer and try to allocated addresses from the specified IPv4 and/or IPv6 ranges. It's assumed that kube-router (or another network controller) will announce the addresses. As the controller uses leases for leader election and updates the service status new RBAC permissions are required.
cloudnativelabs · Aug 10, 2023 · 743ced1 · 743ced1
1 parent 9990f3b
commit 743ced1
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diff --git a/daemonset/generic-kuberouter-all-features-advertise-routes.yaml b/daemonset/generic-kuberouter-all-features-advertise-routes.yaml
@@ -84,6 +84,10 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: spec.nodeName
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: KUBE_ROUTER_CNI_CONF_FILE
           value: /etc/cni/net.d/10-kuberouter.conflist
         livenessProbe:
@@ -206,6 +210,20 @@ rules:
       - get
       - list
       - watch
+  - apiGroups:
+      - "coordination.k8s.io"
+    resources:
+      - leases
+    verbs:
+      - get
+      - create
+      - update
+  - apiGroups:
+      - ""
+    resources:
+      - services/status
+    verbs:
+      - update
 
 ---
 kind: ClusterRoleBinding

diff --git a/daemonset/generic-kuberouter-all-features.yaml b/daemonset/generic-kuberouter-all-features.yaml
@@ -80,6 +80,10 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: spec.nodeName
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: KUBE_ROUTER_CNI_CONF_FILE
           value: /etc/cni/net.d/10-kuberouter.conflist
         livenessProbe:
@@ -202,6 +206,20 @@ rules:
       - get
       - list
       - watch
+  - apiGroups:
+      - "coordination.k8s.io"
+    resources:
+      - leases
+    verbs:
+      - get
+      - create
+      - update
+  - apiGroups:
+      - ""
+    resources:
+      - services/status
+    verbs:
+      - update
 ---
 kind: ClusterRoleBinding
 apiVersion: rbac.authorization.k8s.io/v1

diff --git a/daemonset/generic-kuberouter-only-advertise-routes.yaml b/daemonset/generic-kuberouter-only-advertise-routes.yaml
@@ -43,6 +43,10 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: spec.nodeName
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         livenessProbe:
           httpGet:
             path: /healthz
@@ -114,6 +118,20 @@ rules:
       - get
       - list
       - watch
+  - apiGroups:
+      - "coordination.k8s.io"
+    resources:
+      - leases
+    verbs:
+      - get
+      - create
+      - update
+  - apiGroups:
+      - ""
+    resources:
+      - services/status
+    verbs:
+      - update
 
 ---
 kind: ClusterRoleBinding

diff --git a/daemonset/generic-kuberouter.yaml b/daemonset/generic-kuberouter.yaml
@@ -60,6 +60,10 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: spec.nodeName
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: KUBE_ROUTER_CNI_CONF_FILE
           value: /etc/cni/net.d/10-kuberouter.conflist
         livenessProbe:
@@ -169,6 +173,20 @@ rules:
       - get
       - list
       - watch
+  - apiGroups:
+      - "coordination.k8s.io"
+    resources:
+      - leases
+    verbs:
+      - get
+      - create
+      - update
+  - apiGroups:
+      - ""
+    resources:
+      - services/status
+    verbs:
+      - update
 
 ---
 kind: ClusterRoleBinding

diff --git a/daemonset/kubeadm-kuberouter-all-features-dsr.yaml b/daemonset/kubeadm-kuberouter-all-features-dsr.yaml
@@ -61,6 +61,10 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: spec.nodeName
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: KUBE_ROUTER_CNI_CONF_FILE
           value: /etc/cni/net.d/10-kuberouter.conflist
         livenessProbe:
@@ -185,6 +189,20 @@ rules:
       - get
       - list
       - watch
+  - apiGroups:
+      - "coordination.k8s.io"
+    resources:
+      - leases
+    verbs:
+      - get
+      - create
+      - update
+  - apiGroups:
+      - ""
+    resources:
+      - services/status
+    verbs:
+      - update
 ---
 kind: ClusterRoleBinding
 apiVersion: rbac.authorization.k8s.io/v1

diff --git a/daemonset/kubeadm-kuberouter-all-features-hostport.yaml b/daemonset/kubeadm-kuberouter-all-features-hostport.yaml
@@ -68,6 +68,10 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: spec.nodeName
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: KUBE_ROUTER_CNI_CONF_FILE
           value: /etc/cni/net.d/10-kuberouter.conflist
         livenessProbe:
@@ -184,6 +188,20 @@ rules:
       - get
       - list
       - watch
+  - apiGroups:
+      - "coordination.k8s.io"
+    resources:
+      - leases
+    verbs:
+      - get
+      - create
+      - update
+  - apiGroups:
+      - ""
+    resources:
+      - services/status
+    verbs:
+      - update
 ---
 kind: ClusterRoleBinding
 apiVersion: rbac.authorization.k8s.io/v1

diff --git a/daemonset/kubeadm-kuberouter-all-features.yaml b/daemonset/kubeadm-kuberouter-all-features.yaml
@@ -61,6 +61,10 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: spec.nodeName
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: KUBE_ROUTER_CNI_CONF_FILE
           value: /etc/cni/net.d/10-kuberouter.conflist
         livenessProbe:
@@ -177,6 +181,20 @@ rules:
       - get
       - list
       - watch
+  - apiGroups:
+      - "coordination.k8s.io"
+    resources:
+      - leases
+    verbs:
+      - get
+      - create
+      - update
+  - apiGroups:
+      - ""
+    resources:
+      - services/status
+    verbs:
+      - update
 ---
 kind: ClusterRoleBinding
 apiVersion: rbac.authorization.k8s.io/v1

diff --git a/daemonset/kubeadm-kuberouter.yaml b/daemonset/kubeadm-kuberouter.yaml
@@ -60,6 +60,10 @@ spec:
           valueFrom:
             fieldRef:
               fieldPath: spec.nodeName
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
         - name: KUBE_ROUTER_CNI_CONF_FILE
           value: /etc/cni/net.d/10-kuberouter.conflist
         livenessProbe:
@@ -173,6 +177,20 @@ rules:
       - get
       - list
       - watch
+  - apiGroups:
+      - "coordination.k8s.io"
+    resources:
+      - leases
+    verbs:
+      - get
+      - create
+      - update
+  - apiGroups:
+      - ""
+    resources:
+      - services/status
+    verbs:
+      - update
 ---
 kind: ClusterRoleBinding
 apiVersion: rbac.authorization.k8s.io/v1

diff --git a/docs/load-balancer-allocator.md b/docs/load-balancer-allocator.md
@@ -0,0 +1,81 @@
+# Load Balancer allocator
+
+## What does it do
+
+The load balancer allocator controller looks for services with the type LoadBalancer and tries to allocate addresses for it if needed.
+The controller doesn't enable any announcement of the addresses by default, so `--advertise-loadbalancer-ip` should be set to true and BGP peers configured.
+
+## Load balancer classes
+
+By default the controller allocates addresses for all LoadBalancer services with the where `loadBalancerClass` is empty or set to one of "default" or "kube-router".
+If `--loadbalancer-default-class` is set to false, the controller will only handle services with the class set to "kube-router".
+
+## RBAC permissions
+
+The controller needs some extra permissions to get, create and update leases for leader election and to update services with allocated addresses.
+
+Example permissions:
+```yaml
+kind: ClusterRole
+apiVersion: rbac.authorization.k8s.io/v1
+metadata:
+  name: kube-router
+  namespace: kube-system
+rules:
+  - apiGroups:
+      - "coordination.k8s.io"
+    resources:
+      - leases
+    verbs:
+      - get
+      - create
+      - update
+  - apiGroups:
+      - ""
+    resources:
+      - services/status
+    verbs:
+      - update
+```
+
+## Environment variables
+
+The controller uses the environment variable `POD_NAME` as the identify for the lease used for leader election.
+Using the kubernetes downward api to set `POD_NAME` to the pod name the lease identify will match the current leader.
+```yaml
+---
+apiVersion: apps/v1
+kind: DaemonSet
+metadata:
+  labels:
+    k8s-app: kube-router
+    tier: node
+  name: kube-router
+  namespace: kube-system
+spec:
+  ...
+  template:
+    metadata:
+      ....
+    spec:
+        ...
+        env:
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
+...
+```
+
+The environment variable `POD_NAMESPACE` can also be specified to set the namespace used for the lease.
+By default the namespace is looked up from within the pod using `/var/run/secrets/kubernetes.io/serviceaccount/namespace`.
+
+## Running outside kubernetes
+
+When running the controller outside a pod, both `POD_NAME` and `POD_NAMESPACE` must set for the controller to work.
+`POD_NAME` should be unique per instance, so using for example the hostname of the machine might be a good idea.
+`POD_NAMESPACE` must be the same across all instances running in the same cluster.
+
+## Notes
+
+It's not possible to specify the addresses for the load balancer services. A externalIP service can be used instead.
diff --git a/docs/user-guide.md b/docs/user-guide.md
@@ -94,6 +94,9 @@ Usage of kube-router:
       --ipvs-permit-all                               Enables rule to accept all incoming traffic to service VIP's on the node. (default true)
       --ipvs-sync-period duration                     The delay between ipvs config synchronizations (e.g. '5s', '1m', '2h22m'). Must be greater than 0. (default 5m0s)
       --kubeconfig string                             Path to kubeconfig file with authorization information (the master location is set by the master flag).
+      --loadbalancer-default-class                    Handle loadbalancer services without a class (default true)
+      --loadbalancer-ip-range strings                 CIDR values from which loadbalancer services addresses are assigned (can be specified multiple times)
+      --loadbalancer-sync-period duration             The delay between checking for missed services (e.g. '5s', '1m'). Must be greater than 0. (default 1m0s)
       --masquerade-all                                SNAT all traffic to cluster IP/node port.
       --master string                                 The address of the Kubernetes API server (overrides any value in kubeconfig).
       --metrics-path string                           Prometheus metrics path (default "/metrics")
@@ -113,6 +116,7 @@ Usage of kube-router:
       --router-id string                              BGP router-id. Must be specified in a ipv6 only cluster, "generate" can be specified to generate the router id.
       --routes-sync-period duration                   The delay between route updates and advertisements (e.g. '5s', '1m', '2h22m'). Must be greater than 0. (default 5m0s)
       --run-firewall                                  Enables Network Policy -- sets up iptables to provide ingress firewall for pods. (default true)
+      --run-loadbalancer                              Enable loadbalancer address allocator
       --run-router                                    Enables Pod Networking -- Advertises and learns the routes to Pods via iBGP. (default true)
       --run-service-proxy                             Enables Service Proxy -- sets up IPVS for Kubernetes Services. (default true)
       --runtime-endpoint string                       Path to CRI compatible container runtime socket (used for DSR mode). Currently known working with containerd.

diff --git a/pkg/cmd/kube-router.go b/pkg/cmd/kube-router.go
@@ -8,6 +8,7 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/cloudnativelabs/kube-router/v2/pkg/controllers/lballoc"
 	"github.com/cloudnativelabs/kube-router/v2/pkg/controllers/netpol"
 	"github.com/cloudnativelabs/kube-router/v2/pkg/controllers/proxy"
 	"github.com/cloudnativelabs/kube-router/v2/pkg/controllers/routing"
@@ -204,6 +205,19 @@ func (kr *KubeRouter) Run() error {
 		go npc.Run(healthChan, stopCh, &wg)
 	}
 
+	if kr.Config.RunLoadBalancer {
+		klog.V(0).Info("running load balancer allocator controller")
+		lbc, err := lballoc.NewLoadBalancerController(kr.Client, kr.Config, svcInformer)
+		if err != nil {
+			return errors.New("Failed to create load balancer allocator: " + err.Error())
+		}
+
+		svcInformer.AddEventHandler(lbc)
+
+		wg.Add(1)
+		go lbc.Run(healthChan, stopCh, &wg)
+	}
+
 	// Handle SIGINT and SIGTERM
 	ch := make(chan os.Signal, 1)
 	signal.Notify(ch, syscall.SIGINT, syscall.SIGTERM)