From c91c882c21a9b04344189f59daa6b09bbc9255d5 Mon Sep 17 00:00:00 2001
From: Martijn van Groningen <martijn.v.groningen@gmail.com>
Date: Wed, 13 Oct 2021 09:02:39 +0200
Subject: [PATCH] Add frozen index deprecation check.

Backporting #78915 to 7.x branch.

If an index has `index.frozen` index setting set to `true` then
the deprecation info api will emit a deprecation check.

Relates to #70192
---
 .../xpack/deprecation/DeprecationChecks.java   |  3 ++-
 .../deprecation/IndexDeprecationChecks.java    | 18 ++++++++++++++++++
 .../IndexDeprecationChecksTests.java           | 17 +++++++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/DeprecationChecks.java b/x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/DeprecationChecks.java
index 54500c24e5026..e944ec68fe51a 100644
--- a/x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/DeprecationChecks.java
+++ b/x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/DeprecationChecks.java
@@ -153,7 +153,8 @@ private DeprecationChecks() {
             IndexDeprecationChecks::checkIndexRoutingIncludeSetting,
             IndexDeprecationChecks::checkIndexRoutingExcludeSetting,
             IndexDeprecationChecks::checkIndexMatrixFiltersSetting,
-            IndexDeprecationChecks::checkGeoShapeMappings
+            IndexDeprecationChecks::checkGeoShapeMappings,
+            IndexDeprecationChecks::frozenIndexSettingCheck
         ));
 
     /**
diff --git a/x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecks.java b/x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecks.java
index 0b39e005dc311..6c64c71256cd6 100644
--- a/x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecks.java
+++ b/x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecks.java
@@ -17,6 +17,7 @@
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.IndexingSlowLog;
 import org.elasticsearch.index.mapper.GeoShapeFieldMapper;
+import org.elasticsearch.index.engine.frozen.FrozenEngine;
 import org.elasticsearch.xpack.core.deprecation.DeprecationIssue;
 import org.elasticsearch.index.SearchSlowLog;
 import org.elasticsearch.index.SlowLogLevel;
@@ -420,4 +421,21 @@ static DeprecationIssue checkGeoShapeMappings(IndexMetadata indexMetadata) {
             return new DeprecationIssue(DeprecationIssue.Level.CRITICAL, message, url, details, false, null);
         }
     }
+
+    static DeprecationIssue frozenIndexSettingCheck(IndexMetadata indexMetadata) {
+        Boolean isIndexFrozen = FrozenEngine.INDEX_FROZEN.get(indexMetadata.getSettings());
+        if (Boolean.TRUE.equals(isIndexFrozen)) {
+            String indexName = indexMetadata.getIndex().getName();
+            return new DeprecationIssue(
+                DeprecationIssue.Level.WARNING,
+                "index [" + indexName +
+                    "] is a frozen index. The frozen indices feature is deprecated and will be removed in a future version",
+                "https://www.elastic.co/guide/en/elasticsearch/reference/master/frozen-indices.html",
+                "Frozen indices no longer offer any advantages. Consider cold or frozen tiers in place of frozen indices.",
+                false,
+                null
+            );
+        }
+        return null;
+    }
 }
diff --git a/x-pack/plugin/deprecation/src/test/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecksTests.java b/x-pack/plugin/deprecation/src/test/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecksTests.java
index e9f062c78c5fe..7543d2789062d 100644
--- a/x-pack/plugin/deprecation/src/test/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecksTests.java
+++ b/x-pack/plugin/deprecation/src/test/java/org/elasticsearch/xpack/deprecation/IndexDeprecationChecksTests.java
@@ -23,6 +23,7 @@
 import org.elasticsearch.index.SearchSlowLog;
 import org.elasticsearch.index.SlowLogLevel;
 import org.elasticsearch.index.mapper.FieldNamesFieldMapper;
+import org.elasticsearch.index.engine.frozen.FrozenEngine;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.test.VersionUtils;
 import org.elasticsearch.xpack.core.deprecation.DeprecationIssue;
@@ -654,4 +655,20 @@ public void testAdjacencyMatrixSetting() {
 
         assertWarnings(expectedWarnings);
     }
+
+    public void testFrozenIndex() {
+        Settings.Builder settings = settings(Version.CURRENT);
+        settings.put(FrozenEngine.INDEX_FROZEN.getKey(), true);
+        IndexMetadata indexMetadata = IndexMetadata.builder("test").settings(settings).numberOfShards(1).numberOfReplicas(0).build();
+        List<DeprecationIssue> issues = DeprecationChecks.filterChecks(INDEX_SETTINGS_CHECKS, c -> c.apply(indexMetadata));
+        assertThat(issues, contains(
+            new DeprecationIssue(DeprecationIssue.Level.WARNING,
+                "index [test] is a frozen index. The frozen indices feature is deprecated and will be removed in a future version",
+                "https://www.elastic.co/guide/en/elasticsearch/reference/master/frozen-indices.html",
+                "Frozen indices no longer offer any advantages. Consider cold or frozen tiers in place of frozen indices.",
+                false,
+                null
+            )
+        ));
+    }
 }