Elasticsearch: Discontinue EOL version 6.8 thus whole V6 support

- Remove the whole V6 support as 6.8 was the last supported 6.x version.
- Remove the no longer necessary documentation parts about that version.
- Update the related tests accordingly, including removing the V6 ones.

[1] https://www.elastic.co/support/eol

Change-Id: I4748c9718eec246479a2fae78e5f9b1ef912fb93

20 files changed, 31 insertions, 508 deletions

diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index f35dfc7284..e63e0bea39 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -3047,10 +3047,6 @@ WARNING: Support for Elasticsearch is still experimental and is not recommended
 for production use. For compatibility information, please refer to the
 link:https://www.gerritcodereview.com/elasticsearch.html[project homepage].
 
-In Elasticsearch version 6.2 or later, the open and closed changes are merged
-into the default `_doc` type. The latter is also used for the accounts and groups
-indices starting with Elasticsearch 6.2.
-
 Note that when Gerrit is configured to use Elasticsearch, the Elasticsearch
 server(s) must be reachable during the site initialization.
 
@@ -3080,7 +3076,7 @@ Sets the number of shards to use per index. Refer to the
 link:https://www.elastic.co/guide/en/elasticsearch/reference/current/index-modules.html#_static_index_settings[
 Elasticsearch documentation] for details.
 +
-Defaults to 5 for Elasticsearch versions 5 and 6, and to 1 starting with Elasticsearch 7.
+Defaults to 1.
 
 [[elasticsearch.numberOfReplicas]]elasticsearch.numberOfReplicas::
 +
diff --git a/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java b/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
index 0d1f9cd50a..ed32ce5b28 100644
--- a/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
+++ b/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
@@ -127,7 +127,6 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
   private final SitePaths sitePaths;
   private final String indexNameRaw;
 
-  protected final String type;
   protected final ElasticRestClientProvider client;
   protected final String indexName;
   protected final Gson gson;
@@ -147,7 +146,6 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
     this.indexName = config.getIndexName(indexName, schema.getVersion());
     this.indexNameRaw = indexName;
     this.client = client;
-    this.type = client.adapter().getType();
   }
 
   @Override
@@ -167,7 +165,7 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
 
   @Override
   public void delete(K id) {
-    String uri = getURI(type, BULK);
+    String uri = getURI(BULK);
     Response response = postRequest(uri, getDeleteActions(id), getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
@@ -192,10 +190,8 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
     }
 
     // Recreate the index.
-    String indexCreationFields = concatJsonString(getSettings(client.adapter()), getMappings());
-    response =
-        performRequest(
-            "PUT", indexName + client.adapter().includeTypeNameParam(), indexCreationFields);
+    String indexCreationFields = concatJsonString(getSettings(), getMappings());
+    response = performRequest("PUT", indexName, indexCreationFields);
     statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
       String error = String.format("Failed to create index %s: %s", indexName, statusCode);
@@ -207,26 +203,20 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
 
   protected abstract String getMappings();
 
-  private String getSettings(ElasticQueryAdapter adapter) {
-    return gson.toJson(ImmutableMap.of(SETTINGS, ElasticSetting.createSetting(config, adapter)));
+  private String getSettings() {
+    return gson.toJson(ImmutableMap.of(SETTINGS, ElasticSetting.createSetting(config)));
   }
 
   protected abstract String getId(V v);
 
   protected String getMappingsForSingleType(MappingProperties properties) {
-    return getMappingsFor(client.adapter().getType(), properties);
+    return getMappingsFor(properties);
   }
 
-  protected String getMappingsFor(String type, MappingProperties properties) {
+  protected String getMappingsFor(MappingProperties properties) {
     JsonObject mappings = new JsonObject();
 
-    if (client.adapter().omitType()) {
-      mappings.add(MAPPINGS, gson.toJsonTree(properties));
-    } else {
-      JsonObject mappingType = new JsonObject();
-      mappingType.add(type, gson.toJsonTree(properties));
-      mappings.add(MAPPINGS, gson.toJsonTree(mappingType));
-    }
+    mappings.add(MAPPINGS, gson.toJsonTree(properties));
     return gson.toJson(mappings);
   }
 
@@ -305,15 +295,9 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
     return sortArray;
   }
 
-  protected String getURI(String type, String request) {
+  protected String getURI(String request) {
     try {
-      String encodedIndexName = URLEncoder.encode(indexName, UTF_8.toString());
-      if (SEARCH.equals(request) && client.adapter().omitType()) {
-        return encodedIndexName + "/" + request;
-      }
-      String encodedTypeIfAny =
-          client.adapter().omitType() ? "" : "/" + URLEncoder.encode(type, UTF_8.toString());
-      return encodedIndexName + encodedTypeIfAny + "/" + request;
+      return URLEncoder.encode(indexName, UTF_8.toString()) + "/" + request;
     } catch (UnsupportedEncodingException e) {
       throw new StorageException(e);
     }
@@ -359,12 +343,10 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
   protected class ElasticQuerySource implements DataSource<V> {
     private final QueryOptions opts;
     private final String search;
-    private final String index;
 
-    ElasticQuerySource(Predicate<V> p, QueryOptions opts, String index, JsonArray sortArray)
+    ElasticQuerySource(Predicate<V> p, QueryOptions opts, JsonArray sortArray)
         throws QueryParseException {
       this.opts = opts;
-      this.index = index;
       QueryBuilder qb = queryBuilder.toQueryBuilder(p);
       SearchSourceBuilder searchSource =
           new SearchSourceBuilder(client.adapter())
@@ -392,7 +374,7 @@ abstract class AbstractElasticIndex<K, V> implements Index<K, V> {
 
     private <T> ResultSet<T> readImpl(Function<JsonObject, T> mapper) {
       try {
-        String uri = getURI(index, SEARCH);
+        String uri = getURI(SEARCH);
         Response response =
             performRequest(HttpPost.METHOD_NAME, uri, search, Collections.emptyMap());
         StatusLine statusLine = response.getStatusLine();
diff --git a/java/com/google/gerrit/elasticsearch/ElasticAccountIndex.java b/java/com/google/gerrit/elasticsearch/ElasticAccountIndex.java
index 374120e3e4..bde3ad50b6 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticAccountIndex.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticAccountIndex.java
@@ -74,7 +74,7 @@ public class ElasticAccountIndex extends AbstractElasticIndex<Account.Id, Accoun
   public void replace(AccountState as) {
     BulkRequest bulk = new IndexRequest(getId(as), indexName).add(new UpdateRequest<>(schema, as));
 
-    String uri = getURI(type, BULK);
+    String uri = getURI(BULK);
     Response response = postRequest(uri, bulk, getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
@@ -96,7 +96,6 @@ public class ElasticAccountIndex extends AbstractElasticIndex<Account.Id, Accoun
     return new ElasticQuerySource(
         p,
         opts.filterFields(o -> IndexUtils.accountFields(o, schema.useLegacyNumericFields())),
-        type,
         sortArray);
   }
 
diff --git a/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java b/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java
index a65840044e..2be1585f06 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java
@@ -14,8 +14,6 @@
 
 package com.google.gerrit.elasticsearch;
 
-import static com.google.gerrit.server.index.change.ChangeIndexRewriter.CLOSED_STATUSES;
-import static com.google.gerrit.server.index.change.ChangeIndexRewriter.OPEN_STATUSES;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.Objects.requireNonNull;
 
@@ -23,7 +21,6 @@ import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.ListMultimap;
-import com.google.common.collect.Lists;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.Sets;
 import com.google.gerrit.elasticsearch.ElasticMapping.MappingProperties;
@@ -50,7 +47,6 @@ import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.index.IndexUtils;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gerrit.server.index.change.ChangeIndex;
-import com.google.gerrit.server.index.change.ChangeIndexRewriter;
 import com.google.gerrit.server.project.SubmitRuleOptions;
 import com.google.gerrit.server.query.change.ChangeData;
 import com.google.gson.JsonArray;
@@ -59,7 +55,6 @@ import com.google.gson.JsonObject;
 import com.google.inject.Inject;
 import com.google.inject.assistedinject.Assisted;
 import java.util.Collections;
-import java.util.List;
 import java.util.Optional;
 import java.util.Set;
 import org.apache.http.HttpStatus;
@@ -82,8 +77,6 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
   }
 
   private static final String CHANGES = "changes";
-  private static final String OPEN_CHANGES = "open_" + CHANGES;
-  private static final String CLOSED_CHANGES = "closed_" + CHANGES;
 
   private final ChangeMapping mapping;
   private final ChangeData.Factory changeDataFactory;
@@ -109,7 +102,7 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
   public void replace(ChangeData cd) {
     BulkRequest bulk = new IndexRequest(getId(cd), indexName).add(new UpdateRequest<>(schema, cd));
 
-    String uri = getURI(type, BULK);
+    String uri = getURI(BULK);
     Response response = postRequest(uri, bulk, getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
@@ -122,27 +115,9 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
   @Override
   public DataSource<ChangeData> getSource(Predicate<ChangeData> p, QueryOptions opts)
       throws QueryParseException {
-    Set<Change.Status> statuses = ChangeIndexRewriter.getPossibleStatus(p);
-    List<String> indexes = Lists.newArrayListWithCapacity(2);
-    if (!client.adapter().omitType()) {
-      if (client.adapter().useV6Type()) {
-        if (!Sets.intersection(statuses, OPEN_STATUSES).isEmpty()
-            || !Sets.intersection(statuses, CLOSED_STATUSES).isEmpty()) {
-          indexes.add(ElasticQueryAdapter.V6_TYPE);
-        }
-      } else {
-        if (!Sets.intersection(statuses, OPEN_STATUSES).isEmpty()) {
-          indexes.add(OPEN_CHANGES);
-        }
-        if (!Sets.intersection(statuses, CLOSED_STATUSES).isEmpty()) {
-          indexes.add(CLOSED_CHANGES);
-        }
-      }
-    }
-
     QueryOptions filteredOpts =
         opts.filterFields(o -> IndexUtils.changeFields(o, schema.useLegacyNumericFields()));
-    return new ElasticQuerySource(p, filteredOpts, getURI(indexes), getSortArray());
+    return new ElasticQuerySource(p, filteredOpts, getSortArray());
   }
 
   private JsonArray getSortArray() {
@@ -155,10 +130,6 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
     return sortArray;
   }
 
-  private String getURI(List<String> types) {
-    return String.join(",", types);
-  }
-
   @Override
   protected String getDeleteActions(Change.Id c) {
     return getDeleteRequest(c);
@@ -166,7 +137,7 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
 
   @Override
   protected String getMappings() {
-    return getMappingsFor(client.adapter().getType(), mapping.changes);
+    return getMappingsFor(mapping.changes);
   }
 
   @Override
diff --git a/java/com/google/gerrit/elasticsearch/ElasticConfiguration.java b/java/com/google/gerrit/elasticsearch/ElasticConfiguration.java
index 35c33cb9b4..06b128c102 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticConfiguration.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticConfiguration.java
@@ -44,7 +44,7 @@ class ElasticConfiguration {
 
   static final String DEFAULT_PORT = "9200";
   static final String DEFAULT_USERNAME = "elastic";
-  static final int DEFAULT_NUMBER_OF_SHARDS = 0;
+  static final int DEFAULT_NUMBER_OF_SHARDS = 1;
   static final int DEFAULT_NUMBER_OF_REPLICAS = 1;
   static final int DEFAULT_MAX_RESULT_WINDOW = 10000;
 
@@ -107,10 +107,7 @@ class ElasticConfiguration {
     return String.format("%s%s_%04d", prefix, name, schemaVersion);
   }
 
-  int getNumberOfShards(ElasticQueryAdapter adapter) {
-    if (numberOfShards == DEFAULT_NUMBER_OF_SHARDS) {
-      return adapter.getDefaultNumberOfShards();
-    }
+  int getNumberOfShards() {
     return numberOfShards;
   }
 }
diff --git a/java/com/google/gerrit/elasticsearch/ElasticGroupIndex.java b/java/com/google/gerrit/elasticsearch/ElasticGroupIndex.java
index 3922f89616..241e7fddd9 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticGroupIndex.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticGroupIndex.java
@@ -75,7 +75,7 @@ public class ElasticGroupIndex extends AbstractElasticIndex<AccountGroup.UUID, I
     BulkRequest bulk =
         new IndexRequest(getId(group), indexName).add(new UpdateRequest<>(schema, group));
 
-    String uri = getURI(type, BULK);
+    String uri = getURI(BULK);
     Response response = postRequest(uri, bulk, getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
@@ -90,7 +90,7 @@ public class ElasticGroupIndex extends AbstractElasticIndex<AccountGroup.UUID, I
   public DataSource<InternalGroup> getSource(Predicate<InternalGroup> p, QueryOptions opts)
       throws QueryParseException {
     JsonArray sortArray = getSortArray(GroupField.UUID.getName());
-    return new ElasticQuerySource(p, opts.filterFields(IndexUtils::groupFields), type, sortArray);
+    return new ElasticQuerySource(p, opts.filterFields(IndexUtils::groupFields), sortArray);
   }
 
   @Override
diff --git a/java/com/google/gerrit/elasticsearch/ElasticProjectIndex.java b/java/com/google/gerrit/elasticsearch/ElasticProjectIndex.java
index 7e45f4fc23..36eeca1083 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticProjectIndex.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticProjectIndex.java
@@ -76,7 +76,7 @@ public class ElasticProjectIndex extends AbstractElasticIndex<Project.NameKey, P
         new IndexRequest(projectState.getProject().getName(), indexName)
             .add(new UpdateRequest<>(schema, projectState));
 
-    String uri = getURI(type, BULK);
+    String uri = getURI(BULK);
     Response response = postRequest(uri, bulk, getRefreshParam());
     int statusCode = response.getStatusLine().getStatusCode();
     if (statusCode != HttpStatus.SC_OK) {
@@ -91,7 +91,7 @@ public class ElasticProjectIndex extends AbstractElasticIndex<Project.NameKey, P
   public DataSource<ProjectData> getSource(Predicate<ProjectData> p, QueryOptions opts)
       throws QueryParseException {
     JsonArray sortArray = getSortArray(ProjectField.NAME.getName());
-    return new ElasticQuerySource(p, opts.filterFields(IndexUtils::projectFields), type, sortArray);
+    return new ElasticQuerySource(p, opts.filterFields(IndexUtils::projectFields), sortArray);
   }
 
   @Override
diff --git a/java/com/google/gerrit/elasticsearch/ElasticQueryAdapter.java b/java/com/google/gerrit/elasticsearch/ElasticQueryAdapter.java
index 779d433615..19d990181d 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticQueryAdapter.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticQueryAdapter.java
@@ -14,42 +14,23 @@
 
 package com.google.gerrit.elasticsearch;
 
-import static com.google.gerrit.elasticsearch.ElasticVersion.V6_8;
-
 public class ElasticQueryAdapter {
-  static final String V6_TYPE = "_doc";
-
-  private static final String INCLUDE_TYPE = "include_type_name=true";
   private static final String INDICES = "?allow_no_indices=false";
 
-  private final boolean useV6Type;
-  private final boolean omitType;
-  private final int defaultNumberOfShards;
-
   private final String searchFilteringName;
-  private final String indicesExistParams;
   private final String exactFieldType;
   private final String stringFieldType;
   private final String indexProperty;
   private final String rawFieldsKey;
   private final String versionDiscoveryUrl;
-  private final String includeTypeNameParam;
 
-  ElasticQueryAdapter(ElasticVersion version) {
-    this.useV6Type = version.isV6();
-    this.omitType = version.isV7OrLater();
-    this.defaultNumberOfShards = version.isV7OrLater() ? 1 : 5;
-    this.versionDiscoveryUrl = version.isV6OrLater() ? "/%s*" : "/%s*/_aliases";
+  ElasticQueryAdapter() {
+    this.versionDiscoveryUrl = "/%s*";
     this.searchFilteringName = "_source";
     this.exactFieldType = "keyword";
     this.stringFieldType = "text";
     this.indexProperty = "true";
     this.rawFieldsKey = "_source";
-
-    // Since v6.7 (end-of-life), in fact, for these two parameters:
-    this.indicesExistParams =
-        version.isAtLeastMinorVersion(V6_8) ? INDICES + "&" + INCLUDE_TYPE : INDICES;
-    this.includeTypeNameParam = version.isAtLeastMinorVersion(V6_8) ? "?" + INCLUDE_TYPE : "";
   }
 
   public String searchFilteringName() {
@@ -57,7 +38,7 @@ public class ElasticQueryAdapter {
   }
 
   String indicesExistParams() {
-    return indicesExistParams;
+    return INDICES;
   }
 
   String exactFieldType() {
@@ -76,27 +57,7 @@ public class ElasticQueryAdapter {
     return rawFieldsKey;
   }
 
-  boolean useV6Type() {
-    return useV6Type;
-  }
-
-  boolean omitType() {
-    return omitType;
-  }
-
-  int getDefaultNumberOfShards() {
-    return defaultNumberOfShards;
-  }
-
-  String getType() {
-    return useV6Type() ? V6_TYPE : "";
-  }
-
   String getVersionDiscoveryUrl(String name) {
     return String.format(versionDiscoveryUrl, name);
   }
-
-  String includeTypeNameParam() {
-    return includeTypeNameParam;
-  }
 }
diff --git a/java/com/google/gerrit/elasticsearch/ElasticRestClientProvider.java b/java/com/google/gerrit/elasticsearch/ElasticRestClientProvider.java
index a67de44d0d..f635b23c53 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticRestClientProvider.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticRestClientProvider.java
@@ -65,7 +65,7 @@ class ElasticRestClientProvider implements Provider<RestClient>, LifecycleListen
           client = build();
           ElasticVersion version = getVersion();
           logger.atInfo().log("Elasticsearch integration version %s", version);
-          adapter = new ElasticQueryAdapter(version);
+          adapter = new ElasticQueryAdapter();
         }
       }
     }
diff --git a/java/com/google/gerrit/elasticsearch/ElasticSetting.java b/java/com/google/gerrit/elasticsearch/ElasticSetting.java
index e016efb94e..7ec0566a88 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticSetting.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticSetting.java
@@ -22,18 +22,18 @@ class ElasticSetting {
   private static final ImmutableMap<String, String> CUSTOM_CHAR_MAPPING =
       ImmutableMap.of("\\u002E", "\\u0020", "\\u005F", "\\u0020");
 
-  static SettingProperties createSetting(ElasticConfiguration config, ElasticQueryAdapter adapter) {
-    return new ElasticSetting.Builder().addCharFilter().addAnalyzer().build(config, adapter);
+  static SettingProperties createSetting(ElasticConfiguration config) {
+    return new ElasticSetting.Builder().addCharFilter().addAnalyzer().build(config);
   }
 
   static class Builder {
     private final ImmutableMap.Builder<String, FieldProperties> fields =
         new ImmutableMap.Builder<>();
 
-    SettingProperties build(ElasticConfiguration config, ElasticQueryAdapter adapter) {
+    SettingProperties build(ElasticConfiguration config) {
       SettingProperties properties = new SettingProperties();
       properties.analysis = fields.build();
-      properties.numberOfShards = config.getNumberOfShards(adapter);
+      properties.numberOfShards = config.getNumberOfShards();
       properties.numberOfReplicas = config.numberOfReplicas;
       properties.maxResultWindow = config.maxResultWindow;
       return properties;
diff --git a/java/com/google/gerrit/elasticsearch/ElasticVersion.java b/java/com/google/gerrit/elasticsearch/ElasticVersion.java
index b3f1471517..225ecaac1f 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticVersion.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticVersion.java
@@ -18,7 +18,6 @@ import com.google.common.base.Joiner;
 import java.util.regex.Pattern;
 
 public enum ElasticVersion {
-  V6_8("6.8.*"),
   V7_0("7.0.*"),
   V7_1("7.1.*"),
   V7_2("7.2.*"),
@@ -67,34 +66,6 @@ public enum ElasticVersion {
     return Joiner.on(", ").join(ElasticVersion.values());
   }
 
-  public boolean isV6() {
-    return getMajor() == 6;
-  }
-
-  public boolean isV6OrLater() {
-    return isAtLeastVersion(6);
-  }
-
-  public boolean isV7OrLater() {
-    return isAtLeastVersion(7);
-  }
-
-  private boolean isAtLeastVersion(int major) {
-    return getMajor() >= major;
-  }
-
-  public boolean isAtLeastMinorVersion(ElasticVersion version) {
-    return getMajor().equals(version.getMajor()) && getMinor() >= version.getMinor();
-  }
-
-  private Integer getMajor() {
-    return Integer.valueOf(version.split("\\.")[0]);
-  }
-
-  private Integer getMinor() {
-    return Integer.valueOf(version.split("\\.")[1]);
-  }
-
   @Override
   public String toString() {
     return version;
diff --git a/javatests/com/google/gerrit/acceptance/pgm/ElasticReindexIT.java b/javatests/com/google/gerrit/acceptance/pgm/ElasticReindexIT.java
index 7b99a55e57..f23cc10cb8 100644
--- a/javatests/com/google/gerrit/acceptance/pgm/ElasticReindexIT.java
+++ b/javatests/com/google/gerrit/acceptance/pgm/ElasticReindexIT.java
@@ -25,11 +25,6 @@ import org.eclipse.jgit.lib.Config;
 public class ElasticReindexIT extends AbstractReindexTests {
 
   @ConfigSuite.Default
-  public static Config elasticsearchV6() {
-    return getConfig(ElasticVersion.V6_8);
-  }
-
-  @ConfigSuite.Config
   public static Config elasticsearchV7() {
     return getConfig(ElasticVersion.V7_8);
   }
diff --git a/javatests/com/google/gerrit/acceptance/ssh/ElasticIndexIT.java b/javatests/com/google/gerrit/acceptance/ssh/ElasticIndexIT.java
index 43a5cebf1b..f35bcb79eb 100644
--- a/javatests/com/google/gerrit/acceptance/ssh/ElasticIndexIT.java
+++ b/javatests/com/google/gerrit/acceptance/ssh/ElasticIndexIT.java
@@ -27,11 +27,6 @@ import org.eclipse.jgit.lib.Config;
 public class ElasticIndexIT extends AbstractIndexTests {
 
   @ConfigSuite.Default
-  public static Config elasticsearchV6() {
-    return getConfig(ElasticVersion.V6_8);
-  }
-
-  @ConfigSuite.Config
   public static Config elasticsearchV7() {
     return getConfig(ElasticVersion.V7_8);
   }
diff --git a/javatests/com/google/gerrit/elasticsearch/BUILD b/javatests/com/google/gerrit/elasticsearch/BUILD
index e269fc25a0..be35d5a552 100644
--- a/javatests/com/google/gerrit/elasticsearch/BUILD
+++ b/javatests/com/google/gerrit/elasticsearch/BUILD
@@ -50,8 +50,6 @@ TYPES = [
 
 SUFFIX = "sTest.java"
 
-ELASTICSEARCH_TESTS_V6 = {i: "ElasticV6Query" + i.capitalize() + SUFFIX for i in TYPES}
-
 ELASTICSEARCH_TESTS_V7 = {i: "ElasticV7Query" + i.capitalize() + SUFFIX for i in TYPES}
 
 ELASTICSEARCH_TAGS = [
@@ -61,14 +59,6 @@ ELASTICSEARCH_TAGS = [
 ]
 
 [junit_tests(
-    name = "elasticsearch_query_%ss_test_V6" % name,
-    size = "large",
-    srcs = [src],
-    tags = ELASTICSEARCH_TAGS,
-    deps = ELASTICSEARCH_DEPS + [QUERY_TESTS_DEP % name] + HTTP_TEST_DEPS,
-) for name, src in ELASTICSEARCH_TESTS_V6.items()]
-
-[junit_tests(
     name = "elasticsearch_query_%ss_test_V7" % name,
     size = "large",
     srcs = [src],
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java b/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java
index 48295ea5f9..35c32f3ccf 100644
--- a/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java
+++ b/javatests/com/google/gerrit/elasticsearch/ElasticContainer.java
@@ -39,8 +39,6 @@ public class ElasticContainer extends ElasticsearchContainer {
 
   private static String getImageName(ElasticVersion version) {
     switch (version) {
-      case V6_8:
-        return "blacktop/elasticsearch:6.8.13";
       case V7_0:
         return "blacktop/elasticsearch:7.0.1";
       case V7_1:
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryAccountsTest.java b/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryAccountsTest.java
deleted file mode 100644
index 15d8dd63fe..0000000000
--- a/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryAccountsTest.java
+++ /dev/null
@@ -1,64 +0,0 @@
-// Copyright (C) 2018 The Android Open Source Project
-//
-// 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 com.google.gerrit.elasticsearch;
-
-import com.google.gerrit.server.query.account.AbstractQueryAccountsTest;
-import com.google.gerrit.testing.ConfigSuite;
-import com.google.gerrit.testing.InMemoryModule;
-import com.google.gerrit.testing.IndexConfig;
-import com.google.inject.Guice;
-import com.google.inject.Injector;
-import org.eclipse.jgit.lib.Config;
-import org.junit.AfterClass;
-import org.junit.BeforeClass;
-
-public class ElasticV6QueryAccountsTest extends AbstractQueryAccountsTest {
-  @ConfigSuite.Default
-  public static Config defaultConfig() {
-    return IndexConfig.createForElasticsearch();
-  }
-
-  private static ElasticContainer container;
-
-  @BeforeClass
-  public static void startIndexService() {
-    if (container == null) {
-      // Only start Elasticsearch once
-      container = ElasticContainer.createAndStart(ElasticVersion.V6_8);
-    }
-  }
-
-  @AfterClass
-  public static void stopElasticsearchServer() {
-    if (container != null) {
-      container.stop();
-    }
-  }
-
-  @Override
-  protected void initAfterLifecycleStart() throws Exception {
-    super.initAfterLifecycleStart();
-    ElasticTestUtils.createAllIndexes(injector);
-  }
-
-  @Override
-  protected Injector createInjector() {
-    Config elasticsearchConfig = new Config(config);
-    InMemoryModule.setDefaults(elasticsearchConfig);
-    String indicesPrefix = testName.getSanitizedMethodName();
-    ElasticTestUtils.configure(elasticsearchConfig, container, indicesPrefix);
-    return Guice.createInjector(new InMemoryModule(elasticsearchConfig));
-  }
-}
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryChangesTest.java b/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryChangesTest.java
deleted file mode 100644
index d734f1eb6f..0000000000
--- a/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryChangesTest.java
+++ /dev/null
@@ -1,95 +0,0 @@
-// Copyright (C) 2018 The Android Open Source Project
-//
-// 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 com.google.gerrit.elasticsearch;
-
-import static java.util.concurrent.TimeUnit.MINUTES;
-
-import com.google.gerrit.server.query.change.AbstractQueryChangesTest;
-import com.google.gerrit.testing.ConfigSuite;
-import com.google.gerrit.testing.GerritTestName;
-import com.google.gerrit.testing.InMemoryModule;
-import com.google.gerrit.testing.IndexConfig;
-import com.google.inject.Guice;
-import com.google.inject.Injector;
-import org.apache.http.client.methods.HttpPost;
-import org.apache.http.client.protocol.HttpClientContext;
-import org.apache.http.impl.nio.client.CloseableHttpAsyncClient;
-import org.apache.http.impl.nio.client.HttpAsyncClients;
-import org.eclipse.jgit.lib.Config;
-import org.junit.After;
-import org.junit.AfterClass;
-import org.junit.BeforeClass;
-import org.junit.Rule;
-
-public class ElasticV6QueryChangesTest extends AbstractQueryChangesTest {
-  @ConfigSuite.Default
-  public static Config defaultConfig() {
-    return IndexConfig.createForElasticsearch();
-  }
-
-  private static ElasticContainer container;
-  private static CloseableHttpAsyncClient client;
-
-  @BeforeClass
-  public static void startIndexService() {
-    if (container == null) {
-      // Only start Elasticsearch once
-      container = ElasticContainer.createAndStart(ElasticVersion.V6_8);
-      client = HttpAsyncClients.createDefault();
-      client.start();
-    }
-  }
-
-  @AfterClass
-  public static void stopElasticsearchServer() {
-    if (container != null) {
-      container.stop();
-    }
-  }
-
-  @Rule public final GerritTestName testName = new GerritTestName();
-
-  @After
-  public void closeIndex() throws Exception {
-    // Close the index after each test to prevent exceeding Elasticsearch's
-    // shard limit (see Issue 10120).
-    client
-        .execute(
-            new HttpPost(
-                String.format(
-                    "http://%s:%d/%s*/_close",
-                    container.getHttpHost().getHostName(),
-                    container.getHttpHost().getPort(),
-                    testName.getSanitizedMethodName())),
-            HttpClientContext.create(),
-            null)
-        .get(5, MINUTES);
-  }
-
-  @Override
-  protected void initAfterLifecycleStart() throws Exception {
-    super.initAfterLifecycleStart();
-    ElasticTestUtils.createAllIndexes(injector);
-  }
-
-  @Override
-  protected Injector createInjector() {
-    Config elasticsearchConfig = new Config(config);
-    InMemoryModule.setDefaults(elasticsearchConfig);
-    String indicesPrefix = testName.getSanitizedMethodName();
-    ElasticTestUtils.configure(elasticsearchConfig, container, indicesPrefix);
-    return Guice.createInjector(new InMemoryModule(elasticsearchConfig));
-  }
-}
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryGroupsTest.java b/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryGroupsTest.java
deleted file mode 100644
index 28d798e7c4..0000000000
--- a/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryGroupsTest.java
+++ /dev/null
@@ -1,64 +0,0 @@
-// Copyright (C) 2018 The Android Open Source Project
-//
-// 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 com.google.gerrit.elasticsearch;
-
-import com.google.gerrit.server.query.group.AbstractQueryGroupsTest;
-import com.google.gerrit.testing.ConfigSuite;
-import com.google.gerrit.testing.InMemoryModule;
-import com.google.gerrit.testing.IndexConfig;
-import com.google.inject.Guice;
-import com.google.inject.Injector;
-import org.eclipse.jgit.lib.Config;
-import org.junit.AfterClass;
-import org.junit.BeforeClass;
-
-public class ElasticV6QueryGroupsTest extends AbstractQueryGroupsTest {
-  @ConfigSuite.Default
-  public static Config defaultConfig() {
-    return IndexConfig.createForElasticsearch();
-  }
-
-  private static ElasticContainer container;
-
-  @BeforeClass
-  public static void startIndexService() {
-    if (container == null) {
-      // Only start Elasticsearch once
-      container = ElasticContainer.createAndStart(ElasticVersion.V6_8);
-    }
-  }
-
-  @AfterClass
-  public static void stopElasticsearchServer() {
-    if (container != null) {
-      container.stop();
-    }
-  }
-
-  @Override
-  protected void initAfterLifecycleStart() throws Exception {
-    super.initAfterLifecycleStart();
-    ElasticTestUtils.createAllIndexes(injector);
-  }
-
-  @Override
-  protected Injector createInjector() {
-    Config elasticsearchConfig = new Config(config);
-    InMemoryModule.setDefaults(elasticsearchConfig);
-    String indicesPrefix = testName.getSanitizedMethodName();
-    ElasticTestUtils.configure(elasticsearchConfig, container, indicesPrefix);
-    return Guice.createInjector(new InMemoryModule(elasticsearchConfig));
-  }
-}
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryProjectsTest.java b/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryProjectsTest.java
deleted file mode 100644
index 6658d7244e..0000000000
--- a/javatests/com/google/gerrit/elasticsearch/ElasticV6QueryProjectsTest.java
+++ /dev/null
@@ -1,64 +0,0 @@
-// Copyright (C) 2018 The Android Open Source Project
-//
-// 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 com.google.gerrit.elasticsearch;
-
-import com.google.gerrit.server.query.project.AbstractQueryProjectsTest;
-import com.google.gerrit.testing.ConfigSuite;
-import com.google.gerrit.testing.InMemoryModule;
-import com.google.gerrit.testing.IndexConfig;
-import com.google.inject.Guice;
-import com.google.inject.Injector;
-import org.eclipse.jgit.lib.Config;
-import org.junit.AfterClass;
-import org.junit.BeforeClass;
-
-public class ElasticV6QueryProjectsTest extends AbstractQueryProjectsTest {
-  @ConfigSuite.Default
-  public static Config defaultConfig() {
-    return IndexConfig.createForElasticsearch();
-  }
-
-  private static ElasticContainer container;
-
-  @BeforeClass
-  public static void startIndexService() {
-    if (container == null) {
-      // Only start Elasticsearch once
-      container = ElasticContainer.createAndStart(ElasticVersion.V6_8);
-    }
-  }
-
-  @AfterClass
-  public static void stopElasticsearchServer() {
-    if (container != null) {
-      container.stop();
-    }
-  }
-
-  @Override
-  protected void initAfterLifecycleStart() throws Exception {
-    super.initAfterLifecycleStart();
-    ElasticTestUtils.createAllIndexes(injector);
-  }
-
-  @Override
-  protected Injector createInjector() {
-    Config elasticsearchConfig = new Config(config);
-    InMemoryModule.setDefaults(elasticsearchConfig);
-    String indicesPrefix = testName.getSanitizedMethodName();
-    ElasticTestUtils.configure(elasticsearchConfig, container, indicesPrefix);
-    return Guice.createInjector(new InMemoryModule(elasticsearchConfig));
-  }
-}
diff --git a/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java b/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java
index 9325a1b7bc..5d3d3e06a5 100644
--- a/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java
+++ b/javatests/com/google/gerrit/elasticsearch/ElasticVersionTest.java
@@ -22,9 +22,6 @@ import org.junit.Test;
 public class ElasticVersionTest {
   @Test
   public void supportedVersion() throws Exception {
-    assertThat(ElasticVersion.forVersion("6.8.0")).isEqualTo(ElasticVersion.V6_8);
-    assertThat(ElasticVersion.forVersion("6.8.1")).isEqualTo(ElasticVersion.V6_8);
-
     assertThat(ElasticVersion.forVersion("7.0.0")).isEqualTo(ElasticVersion.V7_0);
     assertThat(ElasticVersion.forVersion("7.0.1")).isEqualTo(ElasticVersion.V7_0);
 
@@ -64,46 +61,4 @@ public class ElasticVersionTest {
             "Unsupported version: [4.0.0]. Supported versions: "
                 + ElasticVersion.supportedVersions());
   }
-
-  @Test
-  public void atLeastMinorVersion() throws Exception {
-    assertThat(ElasticVersion.V6_8.isAtLeastMinorVersion(ElasticVersion.V6_8)).isTrue();
-    assertThat(ElasticVersion.V7_0.isAtLeastMinorVersion(ElasticVersion.V6_8)).isFalse();
-    assertThat(ElasticVersion.V7_1.isAtLeastMinorVersion(ElasticVersion.V6_8)).isFalse();
-    assertThat(ElasticVersion.V7_2.isAtLeastMinorVersion(ElasticVersion.V6_8)).isFalse();
-    assertThat(ElasticVersion.V7_3.isAtLeastMinorVersion(ElasticVersion.V6_8)).isFalse();
-    assertThat(ElasticVersion.V7_4.isAtLeastMinorVersion(ElasticVersion.V6_8)).isFalse();
-    assertThat(ElasticVersion.V7_5.isAtLeastMinorVersion(ElasticVersion.V6_8)).isFalse();
-    assertThat(ElasticVersion.V7_6.isAtLeastMinorVersion(ElasticVersion.V6_8)).isFalse();
-    assertThat(ElasticVersion.V7_7.isAtLeastMinorVersion(ElasticVersion.V6_8)).isFalse();
-    assertThat(ElasticVersion.V7_8.isAtLeastMinorVersion(ElasticVersion.V6_8)).isFalse();
-  }
-
-  @Test
-  public void version6OrLater() throws Exception {
-    assertThat(ElasticVersion.V6_8.isV6OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_0.isV6OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_1.isV6OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_2.isV6OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_3.isV6OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_4.isV6OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_5.isV6OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_6.isV6OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_7.isV6OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_8.isV6OrLater()).isTrue();
-  }
-
-  @Test
-  public void version7OrLater() throws Exception {
-    assertThat(ElasticVersion.V6_8.isV7OrLater()).isFalse();
-    assertThat(ElasticVersion.V7_0.isV7OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_1.isV7OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_2.isV7OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_3.isV7OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_4.isV7OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_5.isV7OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_6.isV7OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_7.isV7OrLater()).isTrue();
-    assertThat(ElasticVersion.V7_8.isV7OrLater()).isTrue();
-  }
 }