add program metrics test

operator/internal/controller/pulumi/metrics_program.go

@@ -26,5 +26,10 @@ func newProgramCallback(_ any) {
 
 // updateProgramCallback is a callback that is called when a Program object is updated.
 func deleteProgramCallback(_ any) {
-	numStacks.Dec()
+	numPrograms.Dec()
+
+	val, err := getGaugeValue(numPrograms)
+	if err == nil && val < 0 {
+		numPrograms.Set(0)
+	}
 }

operator/internal/controller/pulumi/metrics_program_test.go

@@ -0,0 +1,52 @@
+// Copyright 2016-2024, Pulumi Corporation.
+//
+// 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 pulumi
+
+import (
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+var _ = Describe("Program Metrics", Ordered, func() {
+	BeforeAll(func() {
+		numPrograms.Set(0)
+	})
+
+	It("should increment the programs_active metric when a new Program is created", func() {
+		newProgramCallback(nil)
+		Expect(testutil.ToFloat64(numPrograms)).To(Equal(1.0))
+	})
+
+	It("should increment the programs_active metric when another Program is created", func() {
+		newProgramCallback(nil)
+		Expect(testutil.ToFloat64(numPrograms)).To(Equal(2.0))
+	})
+
+	It("should decrement the programs_active metric when a Program is deleted", func() {
+		deleteProgramCallback(nil)
+		Expect(testutil.ToFloat64(numPrograms)).To(Equal(1.0))
+	})
+
+	It("should decrement the programs_active metric when another Program is deleted", func() {
+		deleteProgramCallback(nil)
+		Expect(testutil.ToFloat64(numPrograms)).To(Equal(0.0))
+	})
+
+	It("should not decrement the programs_active metric when a Program is deleted and the metric is already at 0", func() {
+		deleteProgramCallback(nil)
+		Expect(testutil.ToFloat64(numPrograms)).To(Equal(0.0))
+	})
+})

operator/internal/controller/pulumi/metrics_stack.go

@@ -81,6 +81,11 @@ func updateStackReconcilingMetrics(newStack *pulumiv1.Stack) {
 // deleteStackCallback is a callback that is called when a Stack object is deleted.
 func deleteStackCallback(oldObj any) {
 	numStacks.Dec()
+	val, err := getGaugeValue(numStacks)
+	if err == nil && val < 0 {
+		numStacks.Set(0)
+	}
+
 	oldStack, ok := oldObj.(*pulumiv1.Stack)
 	if !ok {
 		return
@@ -89,5 +94,4 @@ func deleteStackCallback(oldObj any) {
 	// Reset any gauge metrics associated with the old stack.
 	numStacksFailing.With(prometheus.Labels{"namespace": oldStack.Namespace, "name": oldStack.Name}).Set(0)
 	numStacksReconciling.With(prometheus.Labels{"namespace": oldStack.Namespace, "name": oldStack.Name}).Set(0)
-
 }

operator/internal/controller/pulumi/metrics_stack_test.go

@@ -43,7 +43,6 @@ var _ = Describe("Stack Metrics", func() {
 		})
 
 		It("should increment the numStacks metric", func() {
-			// Call the newStackCallback function
 			newStackCallback(newStack)
 
 			// Check if the numStacks metric has been incremented
@@ -53,14 +52,40 @@ var _ = Describe("Stack Metrics", func() {
 		})
 
 		It("should increment the numStacks metric again if another stack is created", func() {
-			// Call the newStackCallback function
 			newStackCallback(newStack)
 
 			// Check if the numStacks metric has been incremented
 			expected := 2.0
 			actual := testutil.ToFloat64(numStacks)
 			Expect(actual).To(Equal(expected))
 		})
+
+		It("should decrement the numStacks metric if a stack is deleted", func() {
+			deleteStackCallback(newStack)
+
+			// Check if the numStacks metric has been decremented
+			expected := 1.0
+			actual := testutil.ToFloat64(numStacks)
+			Expect(actual).To(Equal(expected))
+		})
+
+		It("should decrement the numStacks metric again if another stack is deleted", func() {
+			deleteStackCallback(newStack)
+
+			// Check if the numStacks metric has been decremented
+			expected := 0.0
+			actual := testutil.ToFloat64(numStacks)
+			Expect(actual).To(Equal(expected))
+		})
+
+		It("should not decrement the numStacks metric if a stack is deleted and the metric is already at 0", func() {
+			deleteStackCallback(newStack)
+
+			// Check if the numStacks metric has been decremented
+			expected := 0.0
+			actual := testutil.ToFloat64(numStacks)
+			Expect(actual).To(Equal(expected))
+		})
 	})
 
 	Context("when a stack is updated", func() {

operator/internal/controller/pulumi/utils.go

@@ -18,6 +18,9 @@ package pulumi
 
 import (
 	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
 )
 
 func min(a, b time.Duration) time.Duration {
@@ -44,3 +47,13 @@ func exactlyOneOf(these ...bool) bool {
 	}
 	return found
 }
+
+// getGaugeValue returns the value of a gauge metric. This is useful to check that a gauge
+// does not go into negative values.
+func getGaugeValue(metric prometheus.Gauge) (float64, error) {
+	var m = &dto.Metric{}
+	if err := metric.Write(m); err != nil {
+		return 0, err
+	}
+	return m.Gauge.GetValue(), nil
+}