chore: add test for Prometheus v2

Signed-off-by: Jayapriya Pai <slashpai9@gmail.com>

.github/workflows/e2e-prometheus2.yaml

@@ -66,7 +66,7 @@ jobs:
     - name: Run tests
       env:
         E2E_DIAGNOSTIC_DIRECTORY: ${{ env.E2E_DIAGNOSTIC_DIRECTORY }}
-        TEST_EXPERIMENTAL_PROMETHEUS: "true"
+        TEST_PROMETHEUS_V2: "true"
       run: |
         make ${{ matrix.target }}
 

Documentation/compatibility.md

@@ -55,10 +55,6 @@ Prometheus Operator supports all Prometheus versions >= v2.0.0. The operator's e
 * v2.55.1
 * v3.0.0
 * v3.0.1
-* v3.0.0-beta.0
-* v3.0.0-beta.1
-* v3.0.0-rc.0
-* v3.0.0-rc.1
 ```
 
 The end-to-end tests are mostly tested against

cmd/po-docgen/compatibility.go

@@ -27,7 +27,7 @@ type compatibilityMatrix struct {
 
 func getCompatibilityMatrix() compatibilityMatrix {
 	return compatibilityMatrix{
-		PrometheusVersions:  append(operator.PrometheusCompatibilityMatrix, operator.PrometheusExperimentalVersions...),
+		PrometheusVersions:  operator.PrometheusCompatibilityMatrix,
 		DefaultPrometheus:   operator.DefaultPrometheusVersion,
 		DefaultAlertmanager: operator.DefaultAlertmanagerVersion,
 		DefaultThanos:       operator.DefaultThanosVersion,

pkg/operator/defaults.go

@@ -14,7 +14,11 @@
 
 package operator
 
-import "github.com/prometheus/common/version"
+import (
+	"strings"
+
+	"github.com/prometheus/common/version"
+)
 
 const (
 	// DefaultAlertmanagerVersion is a default image tag for the prometheus alertmanager.
@@ -36,8 +40,8 @@ const (
 var (
 	// DefaultPrometheusVersion is a default image tag for the prometheus.
 	DefaultPrometheusVersion = PrometheusCompatibilityMatrix[len(PrometheusCompatibilityMatrix)-1]
-	// DefaultPrometheusExperimentalVersion is a default image tag for the prometheus experimental version (like Prometheus 3 beta).
-	DefaultPrometheusExperimentalVersion = PrometheusExperimentalVersions[len(PrometheusExperimentalVersions)-1]
+	// DefaultPrometheusV2 is latest version of Prometheus v2.
+	DefaultPrometheusV2 = getLatestPrometheusV2()
 	// DefaultPrometheusBaseImage is a base container registry address for the prometheus.
 	DefaultPrometheusBaseImage = "quay.io/prometheus/prometheus"
 	// DefaultPrometheusImage is a default image pulling address for the prometheus.
@@ -78,13 +82,14 @@ var (
 		"v3.0.0",
 		"v3.0.1",
 	}
-
-	// Note: Issues in this version won't be supported by operator till its stable
-	// This is only added for users to try the unstable versions.
-	PrometheusExperimentalVersions = []string{
-		"v3.0.0-beta.0",
-		"v3.0.0-beta.1",
-		"v3.0.0-rc.0",
-		"v3.0.0-rc.1",
-	}
 )
+
+func getLatestPrometheusV2() string {
+	for i, version := range PrometheusCompatibilityMatrix {
+		// Since last v2 version would be one just before the first v3 version
+		if strings.HasPrefix(version, "v3") {
+			return PrometheusCompatibilityMatrix[i-1]
+		}
+	}
+	panic("failed to find a v2.x entry in the compatibility matrix")
+}

test/framework/prometheus.go

@@ -179,9 +179,8 @@ func (f *Framework) CreateCertificateResources(namespace, certsDir string, prwtc
 
 func (f *Framework) MakeBasicPrometheus(ns, name, group string, replicas int32) *monitoringv1.Prometheus {
 	promVersion := operator.DefaultPrometheusVersion
-	// Because Prometheus 3 is supported from version 0.77.0 only
-	if os.Getenv("TEST_EXPERIMENTAL_PROMETHEUS") == "true" && f.operatorVersion.Minor >= 77 {
-		promVersion = operator.DefaultPrometheusExperimentalVersion
+	if os.Getenv("TEST_PROMETHEUS_V2") == "true" {
+		promVersion = operator.DefaultPrometheusV2
 	}
 	return &monitoringv1.Prometheus{
 		ObjectMeta: metav1.ObjectMeta{