Merge pull request #10 from cloudscale-ch/denis/floating-ips

Add support for Floating IPs

Author: href

Makefile

@@ -17,7 +17,7 @@ test:
 			./pkg/internal/compare
 
 integration:
-	K8TEST_PATH=${PWD}/k8test go test -count=1 -tags=integration ./pkg/internal/integration -v
+	K8TEST_PATH=${PWD}/k8test go test -count=1 -tags=integration ./pkg/internal/integration -v -timeout 30m
 
 coverage: test
 	go tool cover -html=cover.out

README.md

@@ -211,6 +211,7 @@ kind: Service
 metadata:
   annotations:
     k8s.cloudscale.ch/loadbalancer-listener-allowed-cidrs: '["1.2.3.0/24"]'
+    k8s.cloudscale.ch/loadbalancer-floating-ips: '["1.2.3.4/32"]'
 ```
 
 The full set of configuration toggles can be found in the [`pkg/cloudscale_ccm/loadbalancer.go`](pkg/cloudscale/ccm/loadbalancer.go) file.

examples/nginx-hello.yml

@@ -0,0 +1,57 @@
+# Deploys the nginxdemos/hello:plain-text container and creates a
+# loadbalancer service for it:
+#
+#     export KUBECONFIG=path/to/kubeconfig
+#     kubectl apply -f nginx-hello.yml
+#
+# Wait for `kubectl describe service hello` to show "Loadbalancer Ensured",
+# then use the IP address found under "LoadBalancer Ingress" to connect to the
+# service.
+#
+# You can also use the following shortcut:
+#
+#     curl http://$(kubectl get service hello -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
+#
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: hello
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      app: hello
+  template:
+    metadata:
+      labels:
+        app: hello
+    spec:
+      containers:
+      - name: hello
+        image: nginxdemos/hello:plain-text
+
+      # Spread the containers across nodes
+      topologySpreadConstraints:
+      - maxSkew: 1
+        topologyKey: kubernetes.io/hostname
+        whenUnsatisfiable: DoNotSchedule
+        labelSelector:
+          matchLabels:
+            app: hello
+---
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app: hello
+  name: hello
+spec:
+  ports:
+  - port: 80
+    protocol: TCP
+    targetPort: 80
+    name: primary
+  selector:
+    app: hello
+  type: LoadBalancer

pkg/cloudscale_ccm/loadbalancer.go

@@ -3,10 +3,13 @@ package cloudscale_ccm
 import (
 	"context"
 	"fmt"
+	"strings"
 
 	"github.com/cloudscale-ch/cloudscale-cloud-controller-manager/pkg/internal/kubeutil"
 	"github.com/cloudscale-ch/cloudscale-go-sdk/v4"
+	"golang.org/x/exp/slices"
 	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/klog/v2"
 )
@@ -73,6 +76,33 @@ const (
 	// resources instead.
 	LoadBalancerVIPAddresses = "k8s.cloudscale.ch/loadbalancer-vip-addresses"
 
+	// LoadBalancerFloatingIPs assigns the given Floating IPs to the
+	// load balancer. The expected value is a list of addresses of the
+	// Floating IPs in CIDR notation. For example:
+	//
+	// ["5.102.150.123/32", "2a06:c01::123/128"]
+	//
+	// If any Floating IP address is assigned to multiple services via this
+	// annotation, the CCM will refuse to update the associated services, as
+	// this is considered a serious configuration issue that has to first be
+	// resolved by the operator.
+	//
+	// While the service being handled needs to have a parseable Floating IP
+	// config, the services it is compared to for conflict detection do not.
+	//
+	// Such services are skipped during conflict detection with the goal
+	// of limiting the impact of config parse errors to the service being
+	// processed.
+	//
+	// Floating IPs already assigned to the loadbalancer, but no longer
+	// present in the annotations, stay on the loadbalancer until another
+	// service requests them. This is due to the fact that it is not possible
+	// to unassign Floating IPs to point to nowhere.
+	//
+	// The Floating IPs are only assigned to the LoadBalancer once it has
+	// been fully created.
+	LoadBalancerFloatingIPs = "k8s.cloudscale.ch/loadbalancer-floating-ips"
+
 	// LoadBalancerPoolAlgorithm defines the load balancing algorithm used
 	// by the loadbalancer. See the API documentation for more information:
 	//
@@ -279,9 +309,9 @@ func (l *loadbalancer) EnsureLoadBalancer(
 	nodes []*v1.Node,
 ) (*v1.LoadBalancerStatus, error) {
 
-	// Skip if the service is not supported by this CCM
+	// Detect configuration issues and abort if they are found
 	serviceInfo := newServiceInfo(service, clusterName)
-	if supported, err := serviceInfo.isSupported(); !supported {
+	if err := l.ensureValidConfig(ctx, serviceInfo); err != nil {
 		return nil, err
 	}
 
@@ -347,9 +377,9 @@ func (l *loadbalancer) UpdateLoadBalancer(
 	nodes []*v1.Node,
 ) error {
 
-	// Skip if the service is not supported by this CCM
+	// Detect configuration issues and abort if they are found
 	serviceInfo := newServiceInfo(service, clusterName)
-	if supported, err := serviceInfo.isSupported(); !supported {
+	if err := l.ensureValidConfig(ctx, serviceInfo); err != nil {
 		return err
 	}
 
@@ -388,9 +418,9 @@ func (l *loadbalancer) EnsureLoadBalancerDeleted(
 	service *v1.Service,
 ) error {
 
-	// Skip if the service is not supported by this CCM
+	// Detect configuration issues and abort if they are found
 	serviceInfo := newServiceInfo(service, clusterName)
-	if supported, err := serviceInfo.isSupported(); !supported {
+	if err := l.ensureValidConfig(ctx, serviceInfo); err != nil {
 		return err
 	}
 
@@ -402,6 +432,120 @@ func (l *loadbalancer) EnsureLoadBalancerDeleted(
 	})
 }
 
+// ensureValidConfig ensures that the configuration can be applied at all,
+// acting as a gate that ensures certain invariants before any changes are
+// made.
+//
+// The general idea is that it's better to not make any chanages if the config
+// is bad, rather than throwing errors later when some changes have already
+// been made.
+func (l *loadbalancer) ensureValidConfig(
+	ctx context.Context, serviceInfo *serviceInfo) error {
+
+	// Skip if the service is not supported by this CCM
+	if supported, err := serviceInfo.isSupported(); !supported {
+		return err
+	}
+
+	// If Floating IPs are used, make sure there are no conflicting
+	// assignment across services.
+	ips, err := l.findIPsAssignedElsewhere(ctx, serviceInfo)
+	if err != nil {
+		return fmt.Errorf("could not parse %s", LoadBalancerFloatingIPs)
+	}
+
+	if len(ips) > 0 {
+
+		info := make([]string, 0, len(ips))
+		for ip, service := range ips {
+			info = append(info, fmt.Sprintf("%s->%s", ip, service))
+		}
+
+		return fmt.Errorf(
+			"at least one Floating IP assigned to service %s is also "+
+				"assigned to another service. Refusing to continue to avoid "+
+				"flapping: %s",
+			serviceInfo.Service.Name,
+			strings.Join(info, ", "),
+		)
+	}
+
+	return nil
+}
+
+// findIPsAssignedElsewhere lists other services and compares their Floating
+// IPs with the ones found on the given service. If an IP is found to be
+// assigned to two services, the IP and the name of the service are returned.
+func (l *loadbalancer) findIPsAssignedElsewhere(
+	ctx context.Context, serviceInfo *serviceInfo) (map[string]string, error) {
+
+	ips, err := serviceInfo.annotationList(LoadBalancerFloatingIPs)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(ips) == 0 {
+		return nil, nil
+	}
+
+	conflicts := make(map[string]string, 0)
+
+	// Unfortuantely, there's no way to filter for the services that matter
+	// here. The only available field selectors for services are
+	// `metadata.name` and `metadata.namespace`.
+	//
+	// To support larger clusters, ensure to not load all services in a
+	// single call.
+	opts := metav1.ListOptions{
+		Continue: "",
+		Limit:    250,
+	}
+
+	svcs := l.k8s.CoreV1().Services("")
+	for {
+		services, err := svcs.List(ctx, opts)
+		if err != nil {
+			return nil, fmt.Errorf("failed to retrieve services: %w", err)
+		}
+
+		for _, service := range services.Items {
+			if service.Spec.Type != "LoadBalancer" {
+				continue
+			}
+			if service.UID == serviceInfo.Service.UID {
+				continue
+			}
+
+			otherInfo := newServiceInfo(&service, serviceInfo.clusterName)
+			other, err := otherInfo.annotationList(LoadBalancerFloatingIPs)
+
+			// Ignore errors loading the IPs of other services, as they would
+			// not be configured either, if the current service is otherwise
+			// okay, it should be able to continue.
+			//
+			// If this is not done, a single configuration error on a service
+			// causes this function to err on all other services.
+			if err != nil {
+				continue
+			}
+
+			for _, ip := range other {
+				if slices.Contains(ips, ip) {
+					conflicts[ip] = service.Name
+				}
+			}
+		}
+
+		if services.Continue == "" {
+			break
+		}
+
+		opts.Continue = services.Continue
+	}
+
+	return conflicts, nil
+}
+
 // loadBalancerStatus generates the v1.LoadBalancerStatus for the given
 // loadbalancer, as required by Kubernetes.
 func loadBalancerStatus(lb *cloudscale.LoadBalancer) *v1.LoadBalancerStatus {

pkg/cloudscale_ccm/reconcile.go

@@ -32,6 +32,9 @@ type lbState struct {
 	// necessarily bound to any given pool.
 	listeners map[*cloudscale.LoadBalancerPool][]cloudscale.
 			LoadBalancerListener
+
+	// The assigned floating IPs
+	floatingIPs []string
 }
 
 func newLbState(lb *cloudscale.LoadBalancer) *lbState {
@@ -44,6 +47,7 @@ func newLbState(lb *cloudscale.LoadBalancer) *lbState {
 			map[*cloudscale.LoadBalancerPool][]cloudscale.LoadBalancerHealthMonitor),
 		listeners: make(
 			map[*cloudscale.LoadBalancerPool][]cloudscale.LoadBalancerListener),
+		floatingIPs: make([]string, 0),
 	}
 }
 
@@ -104,6 +108,14 @@ func desiredLbState(
 		},
 	})
 
+	// Get list of floating IPs if possible
+	ips, err := serviceInfo.annotationList(LoadBalancerFloatingIPs)
+	if err != nil {
+		return nil, fmt.Errorf("could not parse %s", LoadBalancerFloatingIPs)
+	}
+
+	s.floatingIPs = ips
+
 	// Each service port gets its own pool
 	algorithm := serviceInfo.annotation(LoadBalancerPoolAlgorithm)
 	protocol := serviceInfo.annotation(LoadBalancerPoolProtocol)
@@ -297,6 +309,19 @@ func actualLbState(
 		s.listeners[nil] = append(s.listeners[nil], l)
 	}
 
+	// Find all floating IPs assigned to the loadbalancer
+	ips, err := l.client.FloatingIPs.List(ctx)
+	if err != nil {
+		return nil, fmt.Errorf(
+			"lbstate: failed to load floating ips: %w", err)
+	}
+
+	for _, ip := range ips {
+		if ip.LoadBalancer != nil && ip.LoadBalancer.UUID == lb.UUID {
+			s.floatingIPs = append(s.floatingIPs, ip.Network)
+		}
+	}
+
 	return s, nil
 }
 
@@ -673,6 +698,20 @@ func nextLbActions(
 		}
 	}
 
+	// Find the Floating IPs that need to be changed
+	_, assign := compare.Diff(
+		desired.floatingIPs, actual.floatingIPs, func(ip string) string {
+			return ip
+		},
+	)
+
+	for _, ip := range assign {
+		next = append(next, actions.AssignFloatingIP(
+			ip,
+			actual.lb.UUID,
+		))
+	}
+
 	return next, nil
 }
 

pkg/cloudscale_ccm/reconcile_test.go

@@ -231,6 +231,9 @@ func TestActualState(t *testing.T) {
 			},
 		},
 	)
+	server.On("/v1/floating-ips", 200,
+		[]cloudscale.FloatingIP{},
+	)
 	server.Start()
 	defer server.Close()
 

pkg/cloudscale_ccm/service_info.go

@@ -86,6 +86,8 @@ func (s serviceInfo) annotation(key string) string {
 		return s.annotationOrDefault(key, "lb-standard")
 	case LoadBalancerVIPAddresses:
 		return s.annotationOrDefault(key, "[]")
+	case LoadBalancerFloatingIPs:
+		return s.annotationOrDefault(key, "[]")
 	case LoadBalancerPoolAlgorithm:
 		return s.annotationOrDefault(key, "round_robin")
 	case LoadBalancerHealthMonitorDelayS: