controller.go

// Copyright 2024 Google LLC All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"context"
	"fmt"

	compute "cloud.google.com/go/compute/apiv1"
	"cloud.google.com/go/compute/apiv1/computepb"
	"github.com/googleapis/gax-go/v2"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/types"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
)

type runtimeClient interface {
	Get(ctx context.Context, key types.NamespacedName, obj client.Object, opts ...client.GetOption) error
}

type instanceClient interface {
	SetSecurityPolicy(ctx context.Context, req *computepb.SetSecurityPolicyInstanceRequest, opts ...gax.CallOption) (*compute.Operation, error)
}

type reconcileNode struct {
	// client can be used to retrieve objects from the APIServer.
	client            runtimeClient
	instanceClient    instanceClient
	selector          labels.Selector
	securityPolicyURL string
	projectID         string
	processedNodes    map[string]bool
}

// Assert reconcileNode implements reconcile.Reconciler.
var _ reconcile.Reconciler = &reconcileNode{}

func (r *reconcileNode) Reconcile(ctx context.Context, request reconcile.Request) (reconcile.Result, error) {
	log := log.FromContext(ctx)

	// Fetch the Node from the cache
	node := &corev1.Node{}
	if err := r.client.Get(ctx, request.NamespacedName, node); err != nil {
		if errors.IsNotFound(err) {
			log.Info("Node not found, likely deleted", "name", request.NamespacedName.Name)
			return reconcile.Result{}, nil
		}
		return reconcile.Result{}, fmt.Errorf("could not fetch Node: %+v", err)
	}

	// Print the node
	nodeName := node.Name
	if r.processedNodes[nodeName] {
		log.Info("Already processed, skip reconciling", "node", nodeName)
		return reconcile.Result{}, nil
	}
	nodeZone := node.Labels["topology.gke.io/zone"]
	log.Info("Reconciling Node", "name", nodeName, "zone", nodeZone)

	// Check if node label matches the selector
	if !r.selector.Matches(labels.Set(node.Labels)) {
		log.Info("Node does not match label selector, skipping", "name", nodeName)
		return reconcile.Result{}, nil
	}

	// Set Google Cloud Armor security policy for the instance
	spReq := &computepb.SetSecurityPolicyInstanceRequest{
		Project:  r.projectID,
		Zone:     nodeZone,
		Instance: nodeName,
		InstancesSetSecurityPolicyRequestResource: &computepb.InstancesSetSecurityPolicyRequest{
			SecurityPolicy:    &r.securityPolicyURL,
			NetworkInterfaces: []string{"nic0"},
		},
	}

	if _, err := r.instanceClient.SetSecurityPolicy(ctx, spReq); err != nil {
		return reconcile.Result{}, fmt.Errorf("could not set security policy of instance: %+v", err)
	}

	log.Info("Set security policy successfully", "node", nodeName, "policy", r.securityPolicyURL)
	r.processedNodes[nodeName] = true

	return reconcile.Result{}, nil
}