Fail node containing ancient closed index

docs/reference/migration/migrate_8_0/node.asciidoc

@@ -35,4 +35,12 @@ each of these folders to an appropriate location and then configure the
 corresponding node to use this location for its data path. If your nodes each
 have more than one data path in their `path.data` settings then you should move
 all the corresponding subfolders in parallel. Each node uses the same subfolder
-(e.g. `nodes/2`) across all its data paths.
+(e.g. `nodes/2`) across all its data paths.
+
+[float]
+==== Rejection of ancient closed indices
+
+In earlier versions a node would start up even if it had data from indices
+created in a version before the previous major version, as long as those
+indices were closed. {es} now ensures that it is compatible with every index,
+open or closed, at startup time.

server/src/main/java/org/elasticsearch/cluster/metadata/MetaDataIndexUpgradeService.java

@@ -115,18 +115,15 @@ boolean isUpgraded(IndexMetaData indexMetaData) {
     }
 
     /**
-     * Elasticsearch v6.0 no longer supports indices created pre v5.0. All indices
-     * that were created before Elasticsearch v5.0 should be re-indexed in Elasticsearch 5.x
-     * before they can be opened by this version of elasticsearch.
+     * Elasticsearch does not support indices created before the previous major version. They must be reindexed using an earlier version
+     * before they can be opened here.
      */
     private void checkSupportedVersion(IndexMetaData indexMetaData, Version minimumIndexCompatibilityVersion) {
-        if (indexMetaData.getState() == IndexMetaData.State.OPEN && isSupportedVersion(indexMetaData,
-            minimumIndexCompatibilityVersion) == false) {
-            throw new IllegalStateException("The index [" + indexMetaData.getIndex() + "] was created with version ["
+        if (isSupportedVersion(indexMetaData, minimumIndexCompatibilityVersion) == false) {
+            throw new IllegalStateException("The index " + indexMetaData.getIndex() + " was created with version ["
                 + indexMetaData.getCreationVersion() + "] but the minimum compatible version is ["
-
-                + minimumIndexCompatibilityVersion + "]. It should be re-indexed in Elasticsearch " + minimumIndexCompatibilityVersion.major
-                + ".x before upgrading to " + Version.CURRENT + ".");
+                + minimumIndexCompatibilityVersion + "]. It should be re-indexed in Elasticsearch "
+                + minimumIndexCompatibilityVersion.major + ".x before upgrading to " + Version.CURRENT + ".");
         }
     }
 

server/src/test/java/org/elasticsearch/cluster/metadata/MetaDataIndexUpgradeServiceTests.java

@@ -19,6 +19,7 @@
 package org.elasticsearch.cluster.metadata;
 
 import org.elasticsearch.Version;
+import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.settings.IndexScopedSettings;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.indices.mapper.MapperRegistry;
@@ -106,9 +107,9 @@ public void testFailUpgrade() {
             .build());
         String message = expectThrows(IllegalStateException.class, () -> service.upgradeIndexMetaData(metaData,
             Version.CURRENT.minimumIndexCompatibilityVersion())).getMessage();
-        assertEquals(message, "The index [[foo/BOOM]] was created with version [" + indexCreated + "] " +
+        assertThat(message, equalTo("The index [foo/" + metaData.getIndexUUID() + "] was created with version [" + indexCreated + "] " +
              "but the minimum compatible version is [" + minCompat + "]." +
-            " It should be re-indexed in Elasticsearch " + minCompat.major + ".x before upgrading to " + Version.CURRENT.toString() + ".");
+            " It should be re-indexed in Elasticsearch " + minCompat.major + ".x before upgrading to " + Version.CURRENT.toString() + "."));
 
         indexCreated = VersionUtils.randomVersionBetween(random(), minCompat, Version.CURRENT);
         indexUpgraded = VersionUtils.randomVersionBetween(random(), indexCreated, Version.CURRENT);
@@ -160,15 +161,25 @@ private MetaDataIndexUpgradeService getMetaDataIndexUpgradeService() {
     }
 
     public static IndexMetaData newIndexMeta(String name, Settings indexSettings) {
-        Settings build = Settings.builder().put(IndexMetaData.SETTING_VERSION_CREATED, Version.CURRENT)
-            .put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, 1)
-            .put(IndexMetaData.SETTING_NUMBER_OF_SHARDS, 1)
-            .put(IndexMetaData.SETTING_CREATION_DATE, 1)
-            .put(IndexMetaData.SETTING_INDEX_UUID, "BOOM")
-            .put(IndexMetaData.SETTING_VERSION_UPGRADED, Version.CURRENT.minimumIndexCompatibilityVersion())
+        final Settings settings = Settings.builder()
+            .put(IndexMetaData.SETTING_VERSION_CREATED, randomEarlierCompatibleVersion())
+            .put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, between(0, 5))
+            .put(IndexMetaData.SETTING_NUMBER_OF_SHARDS, between(1, 5))
+            .put(IndexMetaData.SETTING_CREATION_DATE, randomNonNegativeLong())
+            .put(IndexMetaData.SETTING_INDEX_UUID, UUIDs.randomBase64UUID(random()))
+            .put(IndexMetaData.SETTING_VERSION_UPGRADED, randomEarlierCompatibleVersion())
             .put(indexSettings)
             .build();
-        return IndexMetaData.builder(name).settings(build).build();
+        final IndexMetaData.Builder indexMetaDataBuilder = IndexMetaData.builder(name).settings(settings);
+        if (randomBoolean()) {
+            indexMetaDataBuilder.state(IndexMetaData.State.CLOSE);
+        }
+        return indexMetaDataBuilder.build();
+    }
+
+    private static Version randomEarlierCompatibleVersion() {
+        return randomValueOtherThan(Version.CURRENT, () -> VersionUtils.randomVersionBetween(random(),
+            Version.CURRENT.minimumIndexCompatibilityVersion(), Version.CURRENT));
     }
 
 }