Flags to configure eventing upgrade tests forwarder (ksvc)

This change is required to complete knative/operator#252

It enables configuring of wathola forwarder implemented as Knative
Service. Configuration is done by using new optional environment
variables.

test/upgrade/prober/configuration.go

@@ -19,8 +19,10 @@ import (
 	"bytes"
 	"fmt"
 	"io/ioutil"
+	"os"
 	"path"
 	"runtime"
+	"strings"
 	"text/template"
 
 	"github.com/wavesoftware/go-ensure"
@@ -118,3 +120,17 @@ func (p *prober) compileTemplate(templateName string, brokerUrl *apis.URL) strin
 	ensure.NoError(tmpl.Execute(&buff, data))
 	return buff.String()
 }
+
+func envflag(name string, defaultValue bool) bool {
+	if value, ok := os.LookupEnv(name); ok {
+		valid := []string{"true", "yes", "enable"}
+		value = strings.ToLower(value)
+		for _, candidate := range valid {
+			if value == candidate {
+				return true
+			}
+		}
+		return false
+	}
+	return defaultValue
+}

test/upgrade/prober/configuration_test.go

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2020 The Knative Authors
+ * 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 prober
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestEnvflag(t *testing.T) {
+	envname := "TestEnvflag"
+	suite := []struct {
+		env          string
+		envSet       bool
+		defaultValue bool
+		out          bool
+	}{
+		{"", false, true, true},
+		{"", true, true, false},
+		{"yes", true, false, true},
+		{"y", true, false, false},
+		{"y", true, true, false},
+		{"true", true, false, true},
+		{"true", true, true, true},
+		{"enable", true, false, true},
+		{"enabled", true, false, false},
+	}
+	for _, s := range suite {
+		t.Run(fmt.Sprintf("env(%t)=%q,def=%t", s.envSet, s.env, s.defaultValue), func(t *testing.T) {
+			if s.envSet {
+				assert.NoError(t, os.Setenv(envname, s.env))
+				defer func() { assert.NoError(t, os.Unsetenv(envname)) }()
+			}
+			result := envflag(envname, s.defaultValue)
+
+			assert.Equal(t, s.out, result)
+		})
+	}
+}

test/upgrade/prober/prober.go

@@ -25,6 +25,11 @@ import (
 	"knative.dev/eventing/test/lib/resources"
 )
 
+const (
+	ServingUseFlag         = "E2E_UPGRADE_TESTS_SERVING_USE"
+	ServingScaleToZeroFlag = "E2E_UPGRADE_TESTS_SERVING_SCALE_TO_ZERO"
+)
+
 var (
 	// FIXME: Interval is set to 200 msec, as lower values will result in errors: knative/eventing#2357
 	// Interval = 10 * time.Millisecond
@@ -69,8 +74,8 @@ func NewConfig(namespace string) *Config {
 		FinishedSleep: 5 * time.Second,
 		FailOnErrors:  true,
 		Serving: ServingConfig{
-			Use:         false,
-			ScaleToZero: true,
+			Use:         envflag(ServingUseFlag, false),
+			ScaleToZero: envflag(ServingScaleToZeroFlag, true),
 		},
 	}
 }
@@ -151,7 +156,7 @@ func (p *prober) remove() {
 	if p.config.Serving.Use {
 		p.removeForwarder()
 	}
-	p.client.Tracker.Clean(true)
+	ensure.NoError(p.client.Tracker.Clean(true))
 }
 
 func newProber(log *zap.SugaredLogger, client *testlib.Client, config *Config) Prober {