From 16ef2baf8a36afddfa45f4f9d560c9593f40eccf Mon Sep 17 00:00:00 2001
From: Matt Moyer <moyerm@vmware.com>
Date: Tue, 22 Sep 2020 09:50:34 -0500
Subject: [PATCH] Sort idpcache keys to make things as deterministic as
 possible.

Signed-off-by: Matt Moyer <moyerm@vmware.com>
---
 .../identityprovider/idpcache/cache.go        |  9 +++++++++
 .../identityprovider/idpcache/cache_test.go   | 19 +++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/internal/controller/identityprovider/idpcache/cache.go b/internal/controller/identityprovider/idpcache/cache.go
index d9ffa614..cea71f14 100644
--- a/internal/controller/identityprovider/idpcache/cache.go
+++ b/internal/controller/identityprovider/idpcache/cache.go
@@ -7,6 +7,7 @@ package idpcache
 import (
 	"context"
 	"fmt"
+	"sort"
 	"sync"
 
 	"k8s.io/apiserver/pkg/authentication/authenticator"
@@ -68,6 +69,14 @@ func (c *Cache) Keys() []Key {
 		result = append(result, key.(Key))
 		return true
 	})
+
+	// Sort the results for consistency.
+	sort.Slice(result, func(i, j int) bool {
+		return result[i].APIGroup < result[j].APIGroup ||
+			result[i].Kind < result[j].Kind ||
+			result[i].Namespace < result[j].Namespace ||
+			result[i].Name < result[j].Name
+	})
 	return result
 }
 
diff --git a/internal/controller/identityprovider/idpcache/cache_test.go b/internal/controller/identityprovider/idpcache/cache_test.go
index e400ff0e..83c49313 100644
--- a/internal/controller/identityprovider/idpcache/cache_test.go
+++ b/internal/controller/identityprovider/idpcache/cache_test.go
@@ -6,6 +6,7 @@ package idpcache
 import (
 	"context"
 	"fmt"
+	"math/rand"
 	"testing"
 	"time"
 
@@ -46,6 +47,24 @@ func TestCache(t *testing.T) {
 		cache.Delete(key)
 	}
 	require.Zero(t, len(cache.Keys()))
+
+	// Fill the cache back up with a fixed set of keys, but inserted in shuffled order.
+	keysInExpectedOrder := []Key{
+		{APIGroup: "a", Kind: "a", Namespace: "a", Name: "a"},
+		{APIGroup: "b", Kind: "a", Namespace: "a", Name: "a"},
+		{APIGroup: "b", Kind: "b", Namespace: "a", Name: "a"},
+		{APIGroup: "b", Kind: "b", Namespace: "b", Name: "a"},
+		{APIGroup: "b", Kind: "b", Namespace: "b", Name: "b"},
+	}
+	for tries := 0; tries < 10; tries++ {
+		cache := New()
+		for _, i := range rand.Perm(len(keysInExpectedOrder)) {
+			cache.Store(keysInExpectedOrder[i], nil)
+		}
+
+		// Expect that they come back out in sorted order.
+		require.Equal(t, keysInExpectedOrder, cache.Keys())
+	}
 }
 
 func TestAuthenticateTokenCredentialRequest(t *testing.T) {