[8.2] Forward port MDP deprecation info api (#86103)

docs/changelog/86103.yaml

@@ -0,0 +1,5 @@
+pr: 86103
+summary: Forward port MDP deprecation info api
+area: Infra/Core
+type: bug
+issues: []

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/DeprecationChecks.java

@@ -41,6 +41,8 @@ private DeprecationChecks() {}
     static final List<
         NodeDeprecationCheck<Settings, PluginsAndModules, ClusterState, XPackLicenseState, DeprecationIssue>> NODE_SETTINGS_CHECKS = List
             .of(
+                NodeDeprecationChecks::checkMultipleDataPaths,
+                NodeDeprecationChecks::checkDataPathsList,
                 NodeDeprecationChecks::checkSharedDataPathSetting,
                 NodeDeprecationChecks::checkReservedPrefixedRealmNames,
                 NodeDeprecationChecks::checkSingleDataNodeWatermarkSetting,

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/NodeDeprecationChecks.java

@@ -114,6 +114,47 @@ static DeprecationIssue checkRemovedSetting(
         return new DeprecationIssue(deprecationLevel, message, url, details, false, meta);
     }
 
+    static DeprecationIssue checkMultipleDataPaths(
+        Settings nodeSettings,
+        PluginsAndModules plugins,
+        final ClusterState clusterState,
+        final XPackLicenseState licenseState
+    ) {
+        List<String> dataPaths = Environment.PATH_DATA_SETTING.get(nodeSettings);
+        if (dataPaths.size() > 1) {
+            return new DeprecationIssue(
+                DeprecationIssue.Level.WARNING,
+                "Specifying multiple data paths is deprecated",
+                "https://ela.st/es-deprecation-7-multiple-paths",
+                "The [path.data] setting contains a list of paths. Specify a single path as a string. Use RAID or other system level "
+                    + "features to utilize multiple disks. If multiple data paths are configured, the node will fail to start in 8.0. ",
+                false,
+                null
+            );
+        }
+        return null;
+    }
+
+    static DeprecationIssue checkDataPathsList(
+        Settings nodeSettings,
+        PluginsAndModules plugins,
+        final ClusterState clusterState,
+        final XPackLicenseState licenseState
+    ) {
+        if (Environment.dataPathUsesList(nodeSettings)) {
+            return new DeprecationIssue(
+                DeprecationIssue.Level.WARNING,
+                "Multiple data paths are not supported",
+                "https://ela.st/es-deprecation-7-multiple-paths",
+                "The [path.data] setting contains a list of paths. Specify a single path as a string. Use RAID or other system level "
+                    + "features to utilize multiple disks. If multiple data paths are configured, the node will fail to start in 8.0. ",
+                false,
+                null
+            );
+        }
+        return null;
+    }
+
     static DeprecationIssue checkSharedDataPathSetting(
         final Settings settings,
         final PluginsAndModules pluginsAndModules,

x-pack/plugin/deprecation/src/test/java/org/elasticsearch/xpack/deprecation/NodeDeprecationChecksTests.java

@@ -27,6 +27,7 @@
 import org.elasticsearch.xpack.core.ilm.LifecycleSettings;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
@@ -75,6 +76,56 @@ public void testRemovedSetting() {
         assertThat(issue.getUrl(), equalTo("https://removed-setting.example.com"));
     }
 
+    public void testMultipleDataPaths() {
+        final Settings settings = Settings.builder().putList("path.data", Arrays.asList("d1", "d2")).build();
+        final XPackLicenseState licenseState = new XPackLicenseState(() -> 0);
+        final DeprecationIssue issue = NodeDeprecationChecks.checkMultipleDataPaths(settings, null, null, licenseState);
+        assertThat(issue, not(nullValue()));
+        assertThat(issue.getLevel(), equalTo(DeprecationIssue.Level.WARNING));
+        assertThat(issue.getMessage(), equalTo("Specifying multiple data paths is deprecated"));
+        assertThat(
+            issue.getDetails(),
+            equalTo(
+                "The [path.data] setting contains a list of paths. Specify a single path as a string. Use RAID or other system level "
+                    + "features to utilize multiple disks. If multiple data paths are configured, the node will fail to start in 8.0. "
+            )
+        );
+        String url = "https://ela.st/es-deprecation-7-multiple-paths";
+        assertThat(issue.getUrl(), equalTo(url));
+    }
+
+    public void testNoMultipleDataPaths() {
+        Settings settings = Settings.builder().put("path.data", "data").build();
+        final XPackLicenseState licenseState = new XPackLicenseState(() -> 0);
+        final DeprecationIssue issue = NodeDeprecationChecks.checkMultipleDataPaths(settings, null, null, licenseState);
+        assertThat(issue, nullValue());
+    }
+
+    public void testDataPathsList() {
+        final Settings settings = Settings.builder().putList("path.data", "d1").build();
+        final XPackLicenseState licenseState = new XPackLicenseState(() -> 0);
+        final DeprecationIssue issue = NodeDeprecationChecks.checkDataPathsList(settings, null, null, licenseState);
+        assertThat(issue, not(nullValue()));
+        assertThat(issue.getLevel(), equalTo(DeprecationIssue.Level.WARNING));
+        assertThat(issue.getMessage(), equalTo("Multiple data paths are not supported"));
+        assertThat(
+            issue.getDetails(),
+            equalTo(
+                "The [path.data] setting contains a list of paths. Specify a single path as a string. Use RAID or other system level "
+                    + "features to utilize multiple disks. If multiple data paths are configured, the node will fail to start in 8.0. "
+            )
+        );
+        String url = "https://ela.st/es-deprecation-7-multiple-paths";
+        assertThat(issue.getUrl(), equalTo(url));
+    }
+
+    public void testNoDataPathsListDefault() {
+        final Settings settings = Settings.builder().build();
+        final XPackLicenseState licenseState = new XPackLicenseState(() -> 0);
+        final DeprecationIssue issue = NodeDeprecationChecks.checkDataPathsList(settings, null, null, licenseState);
+        assertThat(issue, nullValue());
+    }
+
     public void testSharedDataPathSetting() {
         Settings settings = Settings.builder()
             .put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())