Add Solr 10 compatibility support

Solr 10 introduced several breaking changes that prevent the operator
from successfully starting and managing SolrClouds. This change adds
version-conditional behavior for Solr 10 while preserving full backwards
compatibility with Solr 9.x.

Major changes covered:

* solr.xml — Solr 10 removed several `<solrcloud>` parameters
  (genericCoreNodeNames, hostContext, allowPaths, metricsEnabled).
  A new `DefaultSolrXMLForSolr10` template is selected when the image
  tag indicates Solr 10+.

* Host advertise — the `host` system property was renamed to
  `solr.host.advertise`. A `SOLR_HOST_ADVERTISE` env var is now set on
  Solr 10 pods.

* Modules — Solr 10 removed `/opt/solr/contrib/<module>/lib` and
  `/opt/solr/dist`. Modules are now loaded via the `SOLR_MODULES` env
  var, and the operator no longer emits contrib paths in `sharedLib`
  for Solr 10.

* hostPort sysprop — `-DhostPort` is no longer needed in Solr 10 and
  is skipped.

* zkcli.sh removed — `setUrlSchemeClusterPropCmd` (TLS setup) now uses
  `solr zk cp` for Solr 10 instead of the removed
  `cloud-scripts/zkcli.sh`.

* `solr api` CLI — `-get URL` was replaced with `--solr-url URL`.
  Secure probes (`useSecureProbe`) and the e2e helper
  (`callSolrApiInPod`) emit the new flag for Solr 10.

* Basic auth — Solr 10 no longer honors the deprecated
  `-Dbasicauth=user:pass` JAVA_TOOL_OPTIONS path. The e2e helper now
  uses the native `--credentials user:pass` flag for Solr 10.

Version detection lives on the `SolrCloud` type as
`(*SolrCloud).IsSolr10OrLater()`, which parses the major version from
the image tag and treats unparseable tags (e.g. "latest", "nightly")
and a nil `SolrImage` as pre-10 for backwards compatibility. A
package-level `IsSolr10OrLater(imageTag string)` is also exported for
callers that only have a raw image string.

Unit tests cover the version parser, both `solr.xml` templates, and
both branches of `useSecureProbe`. End-to-end tests have been verified
against Solr 10.0.0 across Basic, Scaling (with replica migration),
Security JSON (provided + bootstrapped), TLS (Secrets and Mounted Dir,
including ClientAuth Need/Want, CheckPeerName, VerifyClientHostname),
Local-directory backups (recurring + single), Ingress, and Managed
Rolling Upgrades. Solr 9.8.0 Basic was verified as a regression
baseline.

The Prometheus exporter is not covered: `solr-exporter` was removed
from the Solr distribution in 10, and metrics are now expected to be
scraped from Solr's built-in endpoint. That work is tracked separately
in #820.

Refs #821, #826.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: danielmeint

api/v1beta1/solrcloud_types.go

@@ -1327,6 +1327,42 @@ func (zkInfo ZookeeperConnectionInfo) ZkConnectionString() string {
 	return zkInfo.InternalConnectionString + zkInfo.ChRoot
 }
 
+// Solr10MajorVersion is the version threshold for Solr 10+ incompatible changes.
+const Solr10MajorVersion = 10
+
+// SolrMajorVersion extracts the major version number from a Solr image tag.
+// Returns 0 if the tag cannot be parsed (e.g. "latest", "nightly", custom tags).
+func SolrMajorVersion(imageTag string) int {
+	tag := strings.TrimPrefix(imageTag, "v")
+	if idx := strings.Index(tag, "-"); idx >= 0 {
+		tag = tag[:idx]
+	}
+	major := tag
+	if idx := strings.Index(tag, "."); idx >= 0 {
+		major = tag[:idx]
+	}
+	v, err := strconv.Atoi(major)
+	if err != nil {
+		return 0
+	}
+	return v
+}
+
+// IsSolr10OrLater returns true if the given image tag represents Solr 10.0 or later.
+// Unparseable tags (e.g. "latest") are treated as pre-10 for backwards compatibility.
+func IsSolr10OrLater(imageTag string) bool {
+	return SolrMajorVersion(imageTag) >= Solr10MajorVersion
+}
+
+// IsSolr10OrLater returns true if this SolrCloud's image tag represents Solr 10.0 or later.
+// A nil SolrImage is treated as pre-10.
+func (sc *SolrCloud) IsSolr10OrLater() bool {
+	if sc.Spec.SolrImage == nil {
+		return false
+	}
+	return IsSolr10OrLater(sc.Spec.SolrImage.Tag)
+}
+
 // UsesHeadlessService returns whether the given solrCloud requires a headless service to be created for it.
 // solrCloud: SolrCloud instance
 func (sc *SolrCloud) UsesHeadlessService() bool {

controllers/solrcloud_controller_test.go

@@ -250,7 +250,7 @@ var _ = FDescribe("SolrCloud controller - General", func() {
 		})
 		FIt("has the correct resources", func(ctx context.Context) {
 			By("testing the Solr ConfigMap")
-			configMap := expectConfigMap(ctx, solrCloud, solrCloud.ConfigMapName(), map[string]string{"solr.xml": util.GenerateSolrXMLString("", []string{}, []string{})})
+			configMap := expectConfigMap(ctx, solrCloud, solrCloud.ConfigMapName(), map[string]string{"solr.xml": util.GenerateSolrXMLString("", []string{}, []string{}, false)})
 			Expect(configMap.Labels).To(Equal(util.MergeLabelsOrAnnotations(solrCloud.SharedLabelsWith(solrCloud.Labels), testConfigMapLabels)), "Incorrect configMap labels")
 			Expect(configMap.Annotations).To(Equal(testConfigMapAnnotations), "Incorrect configMap annotations")
 
@@ -661,14 +661,14 @@ var _ = FDescribe("SolrCloud controller - General", func() {
 				g.Expect(logXmlVolMount).To(Not(BeNil()), "Didn't find the log4j2-xml Volume mount")
 				g.Expect(logXmlVolMount.MountPath).To(Equal(expectedMountPath), "log4j2-xml Volume mount has the wrong path")
 
-				g.Expect(found.Spec.Template.Annotations).To(HaveKeyWithValue(util.SolrXmlMd5Annotation, fmt.Sprintf("%x", md5.Sum([]byte(util.GenerateSolrXMLString("", []string{}, []string{}))))), "Custom solr.xml MD5 annotation should be set on the pod template.")
+				g.Expect(found.Spec.Template.Annotations).To(HaveKeyWithValue(util.SolrXmlMd5Annotation, fmt.Sprintf("%x", md5.Sum([]byte(util.GenerateSolrXMLString("", []string{}, []string{}, false))))), "Custom solr.xml MD5 annotation should be set on the pod template.")
 
 				g.Expect(found.Spec.Template.Annotations).To(HaveKeyWithValue(util.LogXmlMd5Annotation, fmt.Sprintf("%x", md5.Sum([]byte(configMap.Data[util.LogXmlFile])))), "Custom log4j2.xml MD5 annotation should be set on the pod template.")
 				expectedEnvVars := map[string]string{"LOG4J_PROPS": fmt.Sprintf("%s/%s", expectedMountPath, util.LogXmlFile)}
 				testPodEnvVariablesWithGomega(g, expectedEnvVars, found.Spec.Template.Spec.Containers[0].Env)
 			})
 
-			expectConfigMap(ctx, solrCloud, fmt.Sprintf("%s-solrcloud-configmap", solrCloud.GetName()), map[string]string{util.SolrXmlFile: util.GenerateSolrXMLString("", []string{}, []string{})})
+			expectConfigMap(ctx, solrCloud, fmt.Sprintf("%s-solrcloud-configmap", solrCloud.GetName()), map[string]string{util.SolrXmlFile: util.GenerateSolrXMLString("", []string{}, []string{}, false)})
 
 			By("updating the user-provided log XML to trigger a pod rolling restart")
 			configMap.Data[util.LogXmlFile] = "<Configuration>Updated!</Configuration>"

controllers/util/solr_security_util.go

@@ -520,7 +520,11 @@ func useSecureProbe(solrCloud *solr.SolrCloud, probe *corev1.Probe, mountPath st
 		javaToolOptionsOutputFilter = ""
 	}
 
-	probeCommand := fmt.Sprintf("%ssolr api -get \"%s://${SOLR_HOST}:%d%s\"%s", javaToolOptionsStr, solrCloud.UrlScheme(false), probe.HTTPGet.Port.IntVal, probe.HTTPGet.Path, javaToolOptionsOutputFilter)
+	apiUrlFlag := "-get"
+	if solrCloud.IsSolr10OrLater() {
+		apiUrlFlag = "--solr-url"
+	}
+	probeCommand := fmt.Sprintf("%ssolr api %s \"%s://${SOLR_HOST}:%d%s\"%s", javaToolOptionsStr, apiUrlFlag, solrCloud.UrlScheme(false), probe.HTTPGet.Port.IntVal, probe.HTTPGet.Path, javaToolOptionsOutputFilter)
 	probeCommand = regexp.MustCompile(`\s+`).ReplaceAllString(strings.TrimSpace(probeCommand), " ")
 
 	// use an Exec instead of an HTTP GET

controllers/util/solr_tls_util.go

@@ -756,8 +756,23 @@ func mountedTLSPath(dir *solr.MountedTLSDirectory, fileName string, defaultName
 	return fmt.Sprintf("%s/%s", dir.Path, fileName)
 }
 
-// Command to set the urlScheme cluster prop to "https"
-func setUrlSchemeClusterPropCmd() string {
+// Command to set the urlScheme cluster prop to "https".
+// Solr 10 removed zkcli.sh, so we use solr zk commands instead.
+func setUrlSchemeClusterPropCmd(isSolr10 bool) string {
+	if isSolr10 {
+		// Use solr zk to read the current clusterprops.json, merge urlScheme, and write it back.
+		// If /clusterprops.json doesn't exist yet, create it with just the urlScheme property.
+		return "solr zk cp zk:/clusterprops.json /tmp/clusterprops.json -z ${ZK_HOST} >/dev/null 2>&1 || echo '{}' > /tmp/clusterprops.json; " +
+			// Use a simple sed/awk to inject or update the urlScheme property
+			"if grep -q 'urlScheme' /tmp/clusterprops.json; then " +
+			"  sed -i 's/\"urlScheme\":\"[^\"]*\"/\"urlScheme\":\"https\"/' /tmp/clusterprops.json; " +
+			"else " +
+			"  sed -i 's/^{/{\"urlScheme\":\"https\",/' /tmp/clusterprops.json; " +
+			"  sed -i 's/,}/}/' /tmp/clusterprops.json; " +
+			"fi; " +
+			"solr zk cp /tmp/clusterprops.json zk:/clusterprops.json -z ${ZK_HOST}; " +
+			"solr zk cp zk:/clusterprops.json /dev/stdout -z ${ZK_HOST}; "
+	}
 	return "/opt/solr/server/scripts/cloud-scripts/zkcli.sh -zkhost ${ZK_HOST} -cmd clusterprop -name urlScheme -val https" +
 		"; /opt/solr/server/scripts/cloud-scripts/zkcli.sh -zkhost ${ZK_HOST} -cmd get /clusterprops.json;"
 }

controllers/util/solr_util.go

@@ -148,9 +148,15 @@ func GenerateStatefulSet(solrCloud *solr.SolrCloud, solrCloudStatus *solr.SolrCl
 		},
 	}
 
+	isSolr10 := solrCloud.IsSolr10OrLater()
+
 	// Keep track of the SolrOpts that the Solr Operator needs to set
 	// These will be added to the SolrOpts given by the user.
-	allSolrOpts := []string{"-DhostPort=$(SOLR_NODE_PORT)"}
+	allSolrOpts := []string{}
+	if !isSolr10 {
+		// The hostPort sysprop is only needed for Solr 9 and earlier
+		allSolrOpts = append(allSolrOpts, "-DhostPort=$(SOLR_NODE_PORT)")
+	}
 
 	// Volumes & Mounts
 	solrVolumes := []corev1.Volume{
@@ -377,19 +383,43 @@ func GenerateStatefulSet(solrCloud *solr.SolrCloud, solrCloudStatus *solr.SolrCl
 			Name:  "SOLR_HOST",
 			Value: solrHostName,
 		},
-		{
+	}
+
+	// Solr 10+ uses SOLR_HOST_ADVERTISE instead of the host setting in solr.xml
+	if isSolr10 {
+		envVars = append(envVars, corev1.EnvVar{
+			Name:  "SOLR_HOST_ADVERTISE",
+			Value: solrHostName,
+		})
+	}
+
+	// Solr 10+ loads modules via SOLR_MODULES env var instead of sharedLib contrib paths
+	if isSolr10 {
+		backupSection, solrModules, _ := GenerateBackupRepositoriesForSolrXml(solrCloud.Spec.BackupRepositories)
+		_ = backupSection
+		solrModules = append(solrModules, solrCloud.Spec.SolrModules...)
+		if len(solrModules) > 0 {
+			envVars = append(envVars, corev1.EnvVar{
+				Name:  "SOLR_MODULES",
+				Value: strings.Join(solrModules, ","),
+			})
+		}
+	}
+
+	envVars = append(envVars,
+		corev1.EnvVar{
 			Name:  "SOLR_LOG_LEVEL",
 			Value: solrCloud.Spec.SolrLogLevel,
 		},
-		{
+		corev1.EnvVar{
 			Name:  "GC_TUNE",
 			Value: solrCloud.Spec.SolrGCTune,
 		},
-		{
+		corev1.EnvVar{
 			Name:  "SOLR_STOP_WAIT",
 			Value: strconv.FormatInt(solrStopWait, 10),
 		},
-	}
+	)
 
 	// Add all necessary information for connection to Zookeeper
 	zkEnvVars, zkSolrOpt, _ := createZkConnectionEnvVars(solrCloud, solrCloudStatus)
@@ -832,6 +862,37 @@ const DefaultSolrXML = `<?xml version="1.0" encoding="UTF-8" ?>
 </solr>
 `
 
+// DefaultSolrXMLForSolr10 is the solr.xml template for Solr 10+.
+// Removed settings that no longer exist in Solr 10:
+//   - hostContext (always "solr", no longer configurable)
+//   - genericCoreNodeNames (always true, no longer configurable)
+//   - allowPaths (removed)
+//   - metrics enabled (removed, metrics always enabled)
+//
+// Note: "host" is still required in solr.xml. Solr 10 renamed the system property
+// from "host" to "solr.host.advertise" but the XML element is still needed.
+const DefaultSolrXMLForSolr10 = `<?xml version="1.0" encoding="UTF-8" ?>
+<solr>
+  %s
+  <solrcloud>
+    <str name="host">${solr.host.advertise:}</str>
+    <int name="hostPort">${solr.port.advertise:80}</int>
+    <int name="zkClientTimeout">${zkClientTimeout:30000}</int>
+    <int name="distribUpdateSoTimeout">${distribUpdateSoTimeout:600000}</int>
+    <int name="distribUpdateConnTimeout">${distribUpdateConnTimeout:60000}</int>
+    <str name="zkCredentialsProvider">${zkCredentialsProvider:org.apache.solr.common.cloud.DefaultZkCredentialsProvider}</str>
+    <str name="zkACLProvider">${zkACLProvider:org.apache.solr.common.cloud.DefaultZkACLProvider}</str>
+  </solrcloud>
+  <shardHandlerFactory name="shardHandlerFactory"
+    class="HttpShardHandlerFactory">
+    <int name="socketTimeout">${socketTimeout:600000}</int>
+    <int name="connTimeout">${connTimeout:60000}</int>
+  </shardHandlerFactory>
+  <int name="maxBooleanClauses">${solr.max.booleanClauses:1024}</int>
+  %s
+</solr>
+`
+
 // GenerateConfigMap returns a new corev1.ConfigMap pointer generated for the SolrCloud instance solr.xml
 // solrCloud: SolrCloud instance
 func GenerateConfigMap(solrCloud *solr.SolrCloud) *corev1.ConfigMap {
@@ -863,28 +924,36 @@ func GenerateSolrXMLStringForCloud(solrCloud *solr.SolrCloud) string {
 	backupSection, solrModules, additionalLibs := GenerateBackupRepositoriesForSolrXml(solrCloud.Spec.BackupRepositories)
 	solrModules = append(solrModules, solrCloud.Spec.SolrModules...)
 	additionalLibs = append(additionalLibs, solrCloud.Spec.AdditionalLibs...)
-	return GenerateSolrXMLString(backupSection, solrModules, additionalLibs)
+	return GenerateSolrXMLString(backupSection, solrModules, additionalLibs, solrCloud.IsSolr10OrLater())
 }
 
-func GenerateSolrXMLString(backupSection string, solrModules []string, additionalLibs []string) string {
-	return fmt.Sprintf(DefaultSolrXML, GenerateAdditionalLibXMLPart(solrModules, additionalLibs), backupSection)
+func GenerateSolrXMLString(backupSection string, solrModules []string, additionalLibs []string, isSolr10 bool) string {
+	template := DefaultSolrXML
+	if isSolr10 {
+		template = DefaultSolrXMLForSolr10
+	}
+	return fmt.Sprintf(template, GenerateAdditionalLibXMLPart(solrModules, additionalLibs, isSolr10), backupSection)
 }
 
-func GenerateAdditionalLibXMLPart(solrModules []string, additionalLibs []string) string {
+func GenerateAdditionalLibXMLPart(solrModules []string, additionalLibs []string, isSolr10 bool) string {
 	libs := make(map[string]bool, 0)
 
 	// Placeholder for users to specify libs via sysprop
 	libs[SysPropLibPlaceholder] = true
 
-	// Add all module library locations
-	if len(solrModules) > 0 {
-		libs[DistLibs] = true
-	}
-	for _, module := range solrModules {
-		libs[fmt.Sprintf(ContribLibs, module)] = true
+	if !isSolr10 {
+		// Solr 9 and earlier: modules are loaded via sharedLib paths to contrib directories
+		if len(solrModules) > 0 {
+			libs[DistLibs] = true
+		}
+		for _, module := range solrModules {
+			libs[fmt.Sprintf(ContribLibs, module)] = true
+		}
 	}
+	// Solr 10+: modules are loaded via SOLR_MODULES env var, not sharedLib contrib paths.
+	// The contrib directory no longer exists in the Solr 10 Docker image.
 
-	// Add all custom library locations
+	// Add all custom library locations (these still work in Solr 10)
 	for _, libPath := range additionalLibs {
 		libs[libPath] = true
 	}
@@ -1250,7 +1319,7 @@ func generateZKInteractionInitContainer(solrCloud *solr.SolrCloud, solrCloudStat
 	}
 
 	if solrCloud.Spec.SolrTLS != nil {
-		cmd += setUrlSchemeClusterPropCmd()
+		cmd += setUrlSchemeClusterPropCmd(solrCloud.IsSolr10OrLater())
 	}
 
 	if security != nil && security.SecurityJson != "" {