fix: ruby injector (#247)

* fix ruby injector

* add test case

Author: danielstokes

internal/apm/ruby.go

@@ -17,6 +17,7 @@ package apm
 
 import (
 	"context"
+	"strings"
 
 	corev1 "k8s.io/api/core/v1"
 
@@ -85,7 +86,9 @@ func (i *RubyInjector) Inject(ctx context.Context, inst current.Instrumentation,
 			Value: rubyOptRequire,
 		})
 	} else if idx > -1 {
-		container.Env[idx].Value = container.Env[idx].Value + envRubyOpt
+		if !strings.Contains(" "+container.Env[idx].Value+" ", " "+rubyOptRequire+" ") {
+			container.Env[idx].Value = container.Env[idx].Value + " " + rubyOptRequire
+		}
 	}
 
 	if isContainerVolumeMissing(container, volumeName) {

internal/apm/ruby_test.go

@@ -95,12 +95,62 @@ func TestRubyInjector_Inject(t *testing.T) {
 				}},
 			inst: current.Instrumentation{Spec: current.InstrumentationSpec{Agent: current.Agent{Language: "ruby"}, LicenseKeySecret: "newrelic-key-secret"}},
 		},
+		{
+			name: "a container, instrumentation, existing RUBYOPT",
+			pod: corev1.Pod{Spec: corev1.PodSpec{Containers: []corev1.Container{
+				{
+					Name: "test",
+					Env: []corev1.EnvVar{
+						{
+							Name:  "RUBYOPT",
+							Value: "-r fakelib",
+						},
+					},
+				},
+			}}},
+			expectedPod: corev1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Labels: map[string]string{
+						DescK8sAgentOperatorVersionLabelName: version.Get().Operator,
+					},
+					Annotations: map[string]string{
+						"newrelic.com/instrumentation-versions": `{"/":"/0"}`,
+					},
+				}, Spec: corev1.PodSpec{
+					Containers: []corev1.Container{{
+						Name: "test",
+						Env: []corev1.EnvVar{
+							{Name: "RUBYOPT", Value: "-r fakelib -r /newrelic-instrumentation/lib/boot/strap"},
+							{Name: "NEW_RELIC_APP_NAME", Value: "test"},
+							{Name: "NEW_RELIC_LABELS", Value: "operator:auto-injection"},
+							{Name: "NEW_RELIC_K8S_OPERATOR_ENABLED", Value: "true"},
+							{Name: "NEW_RELIC_LICENSE_KEY", ValueFrom: &corev1.EnvVarSource{SecretKeyRef: &corev1.SecretKeySelector{LocalObjectReference: corev1.LocalObjectReference{Name: "newrelic-key-secret"}, Key: "new_relic_license_key", Optional: &vtrue}}},
+						},
+						VolumeMounts: []corev1.VolumeMount{{Name: "newrelic-instrumentation", MountPath: "/newrelic-instrumentation"}},
+					}},
+					InitContainers: []corev1.Container{{
+						Name:         "newrelic-instrumentation-ruby",
+						Command:      []string{"cp", "-a", "/instrumentation/.", "/newrelic-instrumentation/"},
+						VolumeMounts: []corev1.VolumeMount{{Name: "newrelic-instrumentation", MountPath: "/newrelic-instrumentation"}},
+					}},
+					Volumes: []corev1.Volume{{Name: "newrelic-instrumentation", VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}}}},
+				}},
+			inst: current.Instrumentation{Spec: current.InstrumentationSpec{Agent: current.Agent{Language: "ruby"}, LicenseKeySecret: "newrelic-key-secret"}},
+		},
 	}
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
 			ctx := context.Background()
 			i := &RubyInjector{}
-			actualPod, err := i.Inject(ctx, test.inst, test.ns, test.pod)
+			// inject multiple times to assert that it's idempotent
+			var err error
+			var actualPod corev1.Pod
+			for ic := 0; ic < 3; ic++ {
+				actualPod, err = i.Inject(ctx, test.inst, test.ns, test.pod)
+				if err != nil {
+					break
+				}
+			}
 			errStr := ""
 			if err != nil {
 				errStr = err.Error()