From 6d68b34521891c9cfd70dc59655e4a4bf8739844 Mon Sep 17 00:00:00 2001
From: Vincent Boulineau <vincent.boulineau@datadoghq.com>
Date: Tue, 20 Feb 2024 21:38:58 +0100
Subject: [PATCH] Add ELB Listener Rules object

---
 resources/elbv2-listenerrule.go | 141 ++++++++++++++++++++++++++++++++
 resources/util.go               |  18 ++++
 2 files changed, 159 insertions(+)
 create mode 100644 resources/elbv2-listenerrule.go

diff --git a/resources/elbv2-listenerrule.go b/resources/elbv2-listenerrule.go
new file mode 100644
index 000000000..a4fe640e9
--- /dev/null
+++ b/resources/elbv2-listenerrule.go
@@ -0,0 +1,141 @@
+package resources
+
+import (
+	"fmt"
+
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/elbv2"
+	"github.com/rebuy-de/aws-nuke/v2/pkg/types"
+	"github.com/sirupsen/logrus"
+)
+
+var elbv2ListenerRulePageSize int64 = 400 // AWS has a limit of 100 rules per listener
+
+type ELBv2ListenerRule struct {
+	svc         *elbv2.ELBV2
+	ruleArn     *string
+	lbName      *string
+	listenerArn *string
+	tags        []*elbv2.Tag
+}
+
+func init() {
+	register("ELBv2ListenerRule", ListELBv2ListenerRules)
+}
+
+func ListELBv2ListenerRules(sess *session.Session) ([]Resource, error) {
+	svc := elbv2.New(sess)
+
+	// We need to retrieve ELBs then Listeners then Rules
+	lbs := make([]*elbv2.LoadBalancer, 0)
+	err := svc.DescribeLoadBalancersPages(
+		nil,
+		func(page *elbv2.DescribeLoadBalancersOutput, lastPage bool) bool {
+			for _, elbv2 := range page.LoadBalancers {
+				lbs = append(lbs, elbv2)
+			}
+			return !lastPage
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	// Required for batched tag retrieval later
+	ruleArns := make([]*string, 0)
+	ruleArnToResource := make(map[string]*ELBv2ListenerRule)
+
+	resources := make([]Resource, 0)
+	for _, lb := range lbs {
+		err := svc.DescribeListenersPages(
+			&elbv2.DescribeListenersInput{
+				LoadBalancerArn: lb.LoadBalancerArn,
+			},
+			func(page *elbv2.DescribeListenersOutput, lastPage bool) bool {
+				for _, listener := range page.Listeners {
+					rules, err := svc.DescribeRules(&elbv2.DescribeRulesInput{
+						ListenerArn: listener.ListenerArn,
+						PageSize:    &elbv2ListenerRulePageSize,
+					})
+					if err == nil {
+						for _, rule := range rules.Rules {
+							// Skip default rules as they cannot be deleted
+							if rule.IsDefault != nil && *rule.IsDefault {
+								continue
+							}
+
+							listenerRule := &ELBv2ListenerRule{
+								svc:         svc,
+								ruleArn:     rule.RuleArn,
+								lbName:      lb.LoadBalancerName,
+								listenerArn: listener.ListenerArn,
+							}
+
+							ruleArns = append(ruleArns, rule.RuleArn)
+							resources = append(resources, listenerRule)
+							ruleArnToResource[*rule.RuleArn] = listenerRule
+						}
+					} else {
+						logrus.
+							WithError(err).
+							WithField("listenerArn", listener.ListenerArn).
+							Error("Failed to list listener rules for listener")
+					}
+				}
+
+				return !lastPage
+			},
+		)
+		if err != nil {
+			logrus.
+				WithError(err).
+				WithField("loadBalancerArn", lb.LoadBalancerArn).
+				Error("Failed to list listeners for load balancer")
+		}
+	}
+
+	// Tags for Rules need to be fetched separately
+	// We can only specify up to 20 in a single call
+	// See: https://github.com/aws/aws-sdk-go/blob/0e8c61841163762f870f6976775800ded4a789b0/service/elbv2/api.go#L5398
+	for _, ruleChunk := range Chunk(ruleArns, 20) {
+		tagResp, err := svc.DescribeTags(&elbv2.DescribeTagsInput{
+			ResourceArns: ruleChunk,
+		})
+		if err != nil {
+			return nil, err
+		}
+		for _, elbv2TagInfo := range tagResp.TagDescriptions {
+			rule := ruleArnToResource[*elbv2TagInfo.ResourceArn]
+			rule.tags = elbv2TagInfo.Tags
+		}
+	}
+
+	return resources, nil
+}
+
+func (e *ELBv2ListenerRule) Remove() error {
+	_, err := e.svc.DeleteRule(&elbv2.DeleteRuleInput{
+		RuleArn: e.ruleArn,
+	})
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (e *ELBv2ListenerRule) Properties() types.Properties {
+	properties := types.NewProperties().
+		Set("ARN", e.ruleArn).
+		Set("ListenerARN", e.listenerArn).
+		Set("LoadBalancerName", e.lbName)
+
+	for _, tagValue := range e.tags {
+		properties.SetTag(tagValue.Key, tagValue.Value)
+	}
+	return properties
+}
+
+func (e *ELBv2ListenerRule) String() string {
+	return fmt.Sprintf("%s -> %s", *e.lbName, *e.ruleArn)
+}
diff --git a/resources/util.go b/resources/util.go
index 22a3e1b2e..b61b83966 100644
--- a/resources/util.go
+++ b/resources/util.go
@@ -36,3 +36,21 @@ func IsAWSError(err error, code string) bool {
 
 	return aerr.Code() == code
 }
+
+func Chunk[T any](slice []T, size int) [][]T {
+	var chunks [][]T
+	for i := 0; i < len(slice); {
+		// Clamp the last chunk to the slice bound as necessary.
+		end := size
+		if l := len(slice[i:]); l < size {
+			end = l
+		}
+
+		// Set the capacity of each chunk so that appending to a chunk does not
+		// modify the original slice.
+		chunks = append(chunks, slice[i:i+end:i+end])
+		i += end
+	}
+
+	return chunks
+}