From 1042d0fc62df98b669ee40ca7ecf1ef1dce94fcf Mon Sep 17 00:00:00 2001
From: Alexander Yastrebov <alexander.yastrebov@zalando.de>
Date: Thu, 8 Feb 2024 17:23:23 +0100
Subject: [PATCH] dataclients/kubernetes: add LoadEndpointAddresses

Add LoadEndpointAddresses to cluster client.
It is similar to caching dataclient GetEndpointAddresses.

Signed-off-by: Alexander Yastrebov <alexander.yastrebov@zalando.de>
---
 dataclients/kubernetes/clusterclient.go  | 38 ++++++++++++++++++++++++
 dataclients/kubernetes/endpointslices.go |  4 ++-
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/dataclients/kubernetes/clusterclient.go b/dataclients/kubernetes/clusterclient.go
index 3b54ef1849..d3c28b8782 100644
--- a/dataclients/kubernetes/clusterclient.go
+++ b/dataclients/kubernetes/clusterclient.go
@@ -532,6 +532,10 @@ func (c *ClusterClient) loadEndpointSlices() (map[definitions.ResourceID]*skippe
 	}
 	log.Debugf("all endpointslices received: %d", len(endpointSlices.Items))
 
+	return mapEndpointSlices(&endpointSlices), nil
+}
+
+func mapEndpointSlices(endpointSlices *endpointSliceList) map[definitions.ResourceID]*skipperEndpointSlice {
 	mapSlices := make(map[definitions.ResourceID][]*endpointSlice)
 	for _, endpointSlice := range endpointSlices.Items {
 		resID := endpointSlice.ToResourceID() // service resource ID
@@ -585,6 +589,40 @@ func (c *ClusterClient) loadEndpointSlices() (map[definitions.ResourceID]*skippe
 			result[resID].Endpoints = append(result[resID].Endpoints, o)
 		}
 	}
+	return result
+}
+
+// LoadEndpointAddresses returns the list of all addresses for the given service using endpoints or endpointslices API.
+func (c *ClusterClient) LoadEndpointAddresses(namespace, name string) ([]string, error) {
+	var result []string
+	if c.enableEndpointSlices {
+		url := fmt.Sprintf(EndpointSlicesNamespaceFmt, namespace) +
+			toLabelSelectorQuery(map[string]string{endpointSliceServiceNameLabel: name})
+
+		var endpointSlices endpointSliceList
+		if err := c.getJSON(url, &endpointSlices); err != nil {
+			return nil, fmt.Errorf("requesting endpointslices for %s/%s failed: %v", namespace, name, err)
+		}
+
+		mapped := mapEndpointSlices(&endpointSlices)
+		if len(mapped) != 1 {
+			return nil, fmt.Errorf("unexpected number of endpoint slices for %s/%s: %d", namespace, name, len(mapped))
+		}
+
+		for _, eps := range mapped {
+			result = eps.addresses()
+			break
+		}
+	} else {
+		url := fmt.Sprintf(EndpointsNamespaceFmt, namespace) + "/" + name
+
+		var ep endpoint
+		if err := c.getJSON(url, &ep); err != nil {
+			return nil, fmt.Errorf("requesting endpoints for %s/%s failed: %v", namespace, name, err)
+		}
+		result = ep.addresses()
+	}
+	sort.Strings(result)
 
 	return result, nil
 }
diff --git a/dataclients/kubernetes/endpointslices.go b/dataclients/kubernetes/endpointslices.go
index 436c3e4a42..e91818c80b 100644
--- a/dataclients/kubernetes/endpointslices.go
+++ b/dataclients/kubernetes/endpointslices.go
@@ -4,6 +4,8 @@ import (
 	"github.com/zalando/skipper/dataclients/kubernetes/definitions"
 )
 
+const endpointSliceServiceNameLabel = "kubernetes.io/service-name"
+
 // There are [1..N] Kubernetes endpointslices created for a single Kubernetes service.
 // Kubernetes endpointslices of a given service can have duplicates with different states.
 // Therefore Kubernetes endpointslices need to be de-duplicated before usage.
@@ -97,7 +99,7 @@ type endpointSlice struct {
 
 // ToResourceID returns the same string for a group endpointlisces created for the same svc
 func (eps *endpointSlice) ToResourceID() definitions.ResourceID {
-	svcName := eps.Meta.Labels["kubernetes.io/service-name"]
+	svcName := eps.Meta.Labels[endpointSliceServiceNameLabel]
 	namespace := eps.Meta.Namespace
 	return newResourceID(namespace, svcName)
 }