Scale-up and scale-down tested

go.mod

@@ -2,6 +2,15 @@ module golang-proxy
 
 go 1.21.0
 
+require (
+	github.com/stretchr/testify v1.8.4
+	k8s.io/api v0.28.3
+	k8s.io/apimachinery v0.28.3
+	k8s.io/client-go v0.28.3
+	k8s.io/utils v0.0.0-20230726121419-3b25d923346b
+	sigs.k8s.io/controller-runtime v0.16.3
+)
+
 require (
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
@@ -36,7 +45,6 @@ require (
 	github.com/prometheus/common v0.44.0 // indirect
 	github.com/prometheus/procfs v0.10.1 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
-	github.com/stretchr/testify v1.8.4 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.25.0 // indirect
 	golang.org/x/exp v0.0.0-20220722155223-a9213eeb770e // indirect
@@ -52,15 +60,10 @@ require (
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
-	k8s.io/api v0.28.3 // indirect
 	k8s.io/apiextensions-apiserver v0.28.3 // indirect
-	k8s.io/apimachinery v0.28.3 // indirect
-	k8s.io/client-go v0.28.3 // indirect
 	k8s.io/component-base v0.28.3 // indirect
 	k8s.io/klog/v2 v2.100.1 // indirect
 	k8s.io/kube-openapi v0.0.0-20230717233707-2695361300d9 // indirect
-	k8s.io/utils v0.0.0-20230726121419-3b25d923346b // indirect
-	sigs.k8s.io/controller-runtime v0.16.3 // indirect
 	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
 	sigs.k8s.io/structured-merge-diff/v4 v4.2.3 // indirect
 	sigs.k8s.io/yaml v1.3.0 // indirect

go.sum

@@ -1,4 +1,6 @@
 github.com/benbjohnson/clock v1.1.0/go.mod h1:J11/hYXuz8f4ySSvYwY0FKfm+ezbsZBKZxNJlLklBHA=
+github.com/benbjohnson/clock v1.3.0 h1:ip6w0uFQkncKQ979AypyG0ER7mqUSBdKLOgAle/AT8A=
+github.com/benbjohnson/clock v1.3.0/go.mod h1:J11/hYXuz8f4ySSvYwY0FKfm+ezbsZBKZxNJlLklBHA=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
@@ -7,11 +9,10 @@ github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ3
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/emicklei/go-restful/v3 v3.9.0 h1:XwGDlfxEnQZzuopoqxwSEllNcCOM9DhhFyhFIIGKwxE=
-github.com/emicklei/go-restful/v3 v3.9.0/go.mod h1:6n3XBCmQQb25CM2LCACGz8ukIrRry+4bhvbpWn3mrbc=
 github.com/emicklei/go-restful/v3 v3.11.0 h1:rAQeMHw1c7zTmncogyy8VvRZwtkmkZ4FxERmMY4rD+g=
 github.com/emicklei/go-restful/v3 v3.11.0/go.mod h1:6n3XBCmQQb25CM2LCACGz8ukIrRry+4bhvbpWn3mrbc=
 github.com/evanphx/json-patch v5.6.0+incompatible h1:jBYDEEiFBPxA0v50tFdvOzQQTCvpL6mnFh5mB2/l16U=
+github.com/evanphx/json-patch v5.6.0+incompatible/go.mod h1:50XU6AFN0ol/bzJsmQLiYLvXMP4fmwYFNcr97nuDLSk=
 github.com/evanphx/json-patch/v5 v5.6.0 h1:b91NhWfaz02IuVxO9faSllyAtNXHMPkC5J8sJCLunww=
 github.com/evanphx/json-patch/v5 v5.6.0/go.mod h1:G79N1coSVB93tBe7j6PhzjmR3/2VvlbKOFpnXhI9Bw4=
 github.com/fsnotify/fsnotify v1.6.0 h1:n+5WquG0fcWoWp6xPWfHdbskMCQaFnG6PfBrh1Ky4HY=
@@ -27,6 +28,8 @@ github.com/go-openapi/jsonreference v0.20.2 h1:3sVjiK66+uXK/6oQ8xgcRKcFgQ5KXa2Kv
 github.com/go-openapi/jsonreference v0.20.2/go.mod h1:Bl1zwGIM8/wsvqjsOQLJ/SH+En5Ap4rVB5KVcIDZG2k=
 github.com/go-openapi/swag v0.22.3 h1:yMBqmnQ0gyZvEb/+KzuWZOXgllrXT4SADYbvDaXHv/g=
 github.com/go-openapi/swag v0.22.3/go.mod h1:UzaqsxGiab7freDnrUUra0MwWfN/q7tE4j+VcZ0yl14=
+github.com/go-task/slim-sprig v0.0.0-20230315185526-52ccab3ef572 h1:tfuBGBXKqDEevZMzYi5KSi8KkcZtzBcTgAUUtapy0OI=
+github.com/go-task/slim-sprig v0.0.0-20230315185526-52ccab3ef572/go.mod h1:9Pwr4B2jHnOSGXyyzV8ROjYa2ojvAY6HCGYYfMoC3Ls=
 github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
 github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
 github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da h1:oI5xCqsCo564l8iNU+DwB5epxmsaqB+rhGL0m5jtYqE=
@@ -44,6 +47,8 @@ github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeN
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/gofuzz v1.2.0 h1:xRy4A+RhZaiKjJ1bPfwQ8sedCA+YS2YcCHW6ec7JMi0=
 github.com/google/gofuzz v1.2.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/google/pprof v0.0.0-20210720184732-4bb14d4b1be1 h1:K6RDEckDVWvDI9JAJYCmNdQXq6neHJOYx3V6jnqNEec=
+github.com/google/pprof v0.0.0-20210720184732-4bb14d4b1be1/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/google/uuid v1.3.0 h1:t6JiXgmwXMjEs8VusXIJk2BXHsn+wx8BZdTaoZ5fu7I=
 github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/imdario/mergo v0.3.6 h1:xTNEAn+kxVO7dTZGu0CegyqKZmoWFI0rF8UxjlB2d28=
@@ -57,8 +62,11 @@ github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
 github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
@@ -71,6 +79,10 @@ github.com/modern-go/reflect2 v1.0.2 h1:xBagoLtFs94CBntxluKeaWgTMpvLxC4ur3nMaC9G
 github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
+github.com/onsi/ginkgo/v2 v2.11.0 h1:WgqUCUt/lT6yXoQ8Wef0fsNn5cAuMK7+KT9UFRz2tcU=
+github.com/onsi/ginkgo/v2 v2.11.0/go.mod h1:ZhrRA5XmEE3x3rhlzamx/JJvujdZoJ2uvgI7kR0iZvM=
+github.com/onsi/gomega v1.27.10 h1:naR28SdDFlqrG6kScpT8VWpu1xWY5nJRCF3XaYyBjhI=
+github.com/onsi/gomega v1.27.10/go.mod h1:RsS8tutOdbdgzbPtzzATp12yT7kM5I5aElG3evPbQ0M=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
@@ -84,6 +96,8 @@ github.com/prometheus/common v0.44.0 h1:+5BrQJwiBB9xsMygAB3TNvpQKOwlkc25LbISbrdO
 github.com/prometheus/common v0.44.0/go.mod h1:ofAIvZbQ1e/nugmZGz4/qCb9Ap1VoSTIO7x0VV9VvuY=
 github.com/prometheus/procfs v0.10.1 h1:kYK1Va/YMlutzCGazswoHKo//tZVlFpKYh+PymziUAg=
 github.com/prometheus/procfs v0.10.1/go.mod h1:nwNm2aOCAYw8uTR/9bWRREkZFxAUcWzPHWJq+XBB/FM=
+github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
+github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
@@ -101,6 +115,8 @@ github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9dec
 github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
 go.uber.org/goleak v1.1.11/go.mod h1:cwTWslyiVhfpKIDGSZEM2HlOvcqm+tG4zioyIeLoqMQ=
+go.uber.org/goleak v1.2.1 h1:NBol2c7O1ZokfZ0LEU9K6Whx/KnwvepVetCUhtKja4A=
+go.uber.org/goleak v1.2.1/go.mod h1:qlT2yGI9QafXHhZZLxlSuNsMw3FFLxBr+tBRlmO1xH4=
 go.uber.org/multierr v1.6.0/go.mod h1:cdWPpRnG4AhwMwsgIHip0KRBQjJy5kYEpYjJxpXp9iU=
 go.uber.org/multierr v1.11.0 h1:blXXJkSxSSfBVBlC76pxqeO+LN3aDfLQo+309xJstO0=
 go.uber.org/multierr v1.11.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
@@ -157,6 +173,8 @@ golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtn
 golang.org/x/tools v0.0.0-20200619180055-7c47624df98f/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
 golang.org/x/tools v0.0.0-20210106214847-113979e3529a/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
 golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
+golang.org/x/tools v0.9.3 h1:Gn1I8+64MsuTb/HpH+LmQtNas23LhUVr3rYZ0eKuaMM=
+golang.org/x/tools v0.9.3/go.mod h1:owI94Op576fPu3cIGQeHs3joujW/2Oc6MtlxbF5dfNc=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
@@ -171,6 +189,7 @@ google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cn
 google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
 gopkg.in/inf.v0 v0.9.1 h1:73M5CoZyi3ZLMOyDlQh031Cx6N9NDJ2Vvfl76EDAgDc=
 gopkg.in/inf.v0 v0.9.1/go.mod h1:cWUDdTG/fYaXco+Dcufb5Vnc6Gp2YChqWtbxRZE0mXw=
@@ -194,8 +213,6 @@ k8s.io/klog/v2 v2.100.1 h1:7WCHKK6K8fNhTqfBhISHQ97KrnJNFZMcQvKp7gP/tmg=
 k8s.io/klog/v2 v2.100.1/go.mod h1:y1WjHnz7Dj687irZUWR/WLkLc5N1YHtjLdmgWjndZn0=
 k8s.io/kube-openapi v0.0.0-20230717233707-2695361300d9 h1:LyMgNKD2P8Wn1iAwQU5OhxCKlKJy0sHc+PcDwFB24dQ=
 k8s.io/kube-openapi v0.0.0-20230717233707-2695361300d9/go.mod h1:wZK2AVp1uHCp4VamDVgBP2COHZjqD1T68Rf0CM3YjSM=
-k8s.io/utils v0.0.0-20230406110748-d93618cff8a2 h1:qY1Ad8PODbnymg2pRbkyMT/ylpTrCM8P2RJ0yroCyIk=
-k8s.io/utils v0.0.0-20230406110748-d93618cff8a2/go.mod h1:OLgZIPagt7ERELqWJFomSt595RzquPNLL48iOWgYOg0=
 k8s.io/utils v0.0.0-20230726121419-3b25d923346b h1:sgn3ZU783SCgtaSJjpcVVlRqd6GSnlTLKgpAAttJvpI=
 k8s.io/utils v0.0.0-20230726121419-3b25d923346b/go.mod h1:OLgZIPagt7ERELqWJFomSt595RzquPNLL48iOWgYOg0=
 sigs.k8s.io/controller-runtime v0.16.3 h1:2TuvuokmfXvDUamSx1SuAOO3eTyye+47mJCigwG62c4=

handler.go

@@ -85,10 +85,20 @@ func parseModel(r *http.Request) (string, *http.Request, error) {
 	return payload.Model, proxyReq, nil
 }
 
+// AdditionalProxyRewrite is an injection point for modifying proxy requests.
+// Used in tests.
+var AdditionalProxyRewrite = func(*httputil.ProxyRequest) {}
+
 func newReverseProxy(host string) *httputil.ReverseProxy {
-	proxy := httputil.NewSingleHostReverseProxy(&url.URL{
-		Scheme: "http",
-		Host:   host,
-	})
+	proxy := &httputil.ReverseProxy{
+		Rewrite: func(r *httputil.ProxyRequest) {
+			r.SetURL(&url.URL{
+				Scheme: "http",
+				Host:   host,
+			})
+			r.Out.Host = r.In.Host
+			AdditionalProxyRewrite(r)
+		},
+	}
 	return proxy
 }

integration_test.go

@@ -28,21 +28,74 @@ func TestIntegration(t *testing.T) {
 
 	require.NoError(t, testK8sClient.Create(testCtx, deploy))
 
+	backendComplete := make(chan struct{})
+
 	backendRequests := &atomic.Int32{}
 	testBackend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		backendRequests.Add(1)
+		<-backendComplete
 		w.WriteHeader(200)
 	}))
+
+	// Mock an EndpointSlice.
 	testBackendURL, err := url.Parse(testBackend.URL)
 	require.NoError(t, err)
 	testBackendPort, err := strconv.Atoi(testBackendURL.Port())
-	require.NoError(t, testK8sClient.Create(testCtx, endpointSlice(modelName, testBackendURL.Hostname(), int32(testBackendPort))))
+	require.NoError(t, testK8sClient.Create(testCtx,
+		endpointSlice(
+			modelName,
+			testBackendURL.Hostname(),
+			int32(testBackendPort),
+		),
+	))
 
+	// Wait for deployment mapping to sync.
+	time.Sleep(3 * time.Second)
+
+	// Send request number 1
 	var wg sync.WaitGroup
+	sendRequests(t, &wg, modelName, 1)
+	requireDeploymentReplicas(t, deploy, 1)
+	require.Equal(t, int32(1), backendRequests.Load(), "ensure the request made its way to the backend")
+	completeRequests(backendComplete, 1)
+
+	// Ensure the deployment scaled scaled past 1.
+	sendRequests(t, &wg, modelName, 2)
+	requireDeploymentReplicas(t, deploy, 2)
+
+	// Make sure deployment will not be scaled past default max (3).
+	sendRequests(t, &wg, modelName, 2)
+	requireDeploymentReplicas(t, deploy, 3)
+
+	// Have the mock backend respond to the remaining 4 requests.
+	completeRequests(backendComplete, 4)
+
+	// Ensure scale-down.
+	requireDeploymentReplicas(t, deploy, 0)
+
+	t.Logf("Waiting for wait group")
+	wg.Wait()
+}
+
+func requireDeploymentReplicas(t *testing.T, deploy *appsv1.Deployment, n int32) {
+	require.EventuallyWithT(t, func(t *assert.CollectT) {
+		err := testK8sClient.Get(testCtx, types.NamespacedName{Namespace: deploy.Namespace, Name: deploy.Name}, deploy)
+		assert.NoError(t, err, "getting the deployment")
+		assert.NotNil(t, deploy.Spec.Replicas, "scale-up should have occurred")
+		assert.Equal(t, *deploy.Spec.Replicas, n, "scale-up should have occurred")
+	}, 3*time.Second, time.Second/2, "waiting for the deployment to be scaled up")
+}
+
+func sendRequests(t *testing.T, wg *sync.WaitGroup, modelName string, n int) {
+	for i := 0; i < n; i++ {
+		sendRequest(t, wg, modelName)
+	}
+}
+
+func sendRequest(t *testing.T, wg *sync.WaitGroup, modelName string) {
 	wg.Add(1)
 	go func() {
 		defer wg.Done()
-		time.Sleep(3 * time.Second)
 
 		body := []byte(fmt.Sprintf(`{"model": %q}`, modelName))
 		req, err := http.NewRequest(http.MethodPost, testServer.URL, bytes.NewReader(body))
@@ -51,17 +104,13 @@ func TestIntegration(t *testing.T) {
 		res, err := testHTTPClient.Do(req)
 		require.NoError(t, err)
 		require.Equal(t, 200, res.StatusCode)
-		require.Equal(t, int32(1), backendRequests.Load())
 	}()
+}
 
-	require.EventuallyWithT(t, func(t *assert.CollectT) {
-		err := testK8sClient.Get(testCtx, types.NamespacedName{Namespace: deploy.Namespace, Name: deploy.Name}, deploy)
-		assert.NoError(t, err, "getting the deployment")
-		assert.GreaterOrEqual(t, deploy.Spec.Replicas, 1, "scale-up should have occurred")
-	}, 3*time.Second, time.Second/2, "waiting for the deployment to be scaled up")
-
-	t.Logf("Waiting for wait group")
-	wg.Wait()
+func completeRequests(c chan struct{}, n int) {
+	for i := 0; i < n; i++ {
+		c <- struct{}{}
+	}
 }
 
 func testDeployment(name string) *appsv1.Deployment {
@@ -93,11 +142,6 @@ func testDeployment(name string) *appsv1.Deployment {
 						{
 							Name:  "model",
 							Image: "some-model:1.2.3",
-							Ports: []corev1.ContainerPort{
-								{
-									ContainerPort: 80,
-								},
-							},
 						},
 					},
 				},
@@ -118,7 +162,8 @@ func endpointSlice(name, ip string, port int32) *disv1.EndpointSlice {
 		AddressType: disv1.AddressTypeIPv4,
 		Endpoints: []disv1.Endpoint{
 			{
-				Addresses: []string{ip},
+				// Address is not used, see TestMain() where this is re-written at request-time.
+				Addresses: []string{"10.0.0.10"},
 				Conditions: disv1.EndpointConditions{
 					Ready:       ptr.To(true),
 					Serving:     ptr.To(true),

main_test.go

@@ -5,6 +5,8 @@ import (
 	"log"
 	"net/http"
 	"net/http/httptest"
+	"net/http/httputil"
+	"net/url"
 	"os"
 	"testing"
 	"time"
@@ -29,8 +31,14 @@ var (
 )
 
 func TestMain(m *testing.M) {
-	testCtx, testCancel = context.WithCancel(context.TODO())
-
+	AdditionalProxyRewrite = func(r *httputil.ProxyRequest) {
+		// EndpointSlices do not allow for specifying local IPs (used in mock backend)
+		// so we remap the requests here.
+		r.SetURL(&url.URL{
+			Scheme: r.Out.URL.Scheme,
+			Host:   "127.0.0.1:" + r.Out.URL.Port(),
+		})
+	}
 	log.Println("bootstrapping test environment")
 	testEnv = &envtest.Environment{}
 	cfg, err := testEnv.Start()
@@ -41,6 +49,8 @@ func TestMain(m *testing.M) {
 	testK8sClient, err = client.New(cfg, client.Options{Scheme: scheme})
 	requireNoError(err)
 
+	testCtx, testCancel = context.WithCancel(ctrl.SetupSignalHandler())
+
 	requireNoError(testK8sClient.Create(testCtx, &corev1.Namespace{
 		ObjectMeta: metav1.ObjectMeta{Name: testNamespace},
 	}))
@@ -62,11 +72,11 @@ func TestMain(m *testing.M) {
 	scaler, err := NewDeploymentManager(mgr)
 	requireNoError(err)
 	scaler.Namespace = testNamespace
-	scaler.ScaleDownPeriod = 30 * time.Second
+	scaler.ScaleDownPeriod = 1 * time.Second
 
 	autoscaler := NewAutoscaler()
-	autoscaler.Interval = 3 * time.Second
-	autoscaler.AverageCount = 10 // 10 * 3 seconds = 30 sec avg
+	autoscaler.Interval = 1 * time.Second
+	autoscaler.AverageCount = 1 // 10 * 3 seconds = 30 sec avg
 	autoscaler.Scaler = scaler
 	autoscaler.FIFO = fifo
 	go autoscaler.Start()
@@ -79,11 +89,9 @@ func TestMain(m *testing.M) {
 	testServer = httptest.NewServer(handler)
 	defer testServer.Close()
 
-	ctx := ctrl.SetupSignalHandler()
-
 	go func() {
 		log.Println("starting manager")
-		requireNoError(mgr.Start(ctx))
+		requireNoError(mgr.Start(testCtx))
 	}()
 
 	log.Println("running tests")