Introduce string constant for readonly setting (#68291)

A blob store repository can be put in readonly mode by setting
`readonly: true` in its settings. In the codebase the setting key is
just the literal string `"readonly"` wherever it's used and it takes
some effort to determine what the right setting name is, in particular
to check each time that it's not spelled `"read_only"`.

This commit replaces those literal `"readonly"` strings with the
`BlobStoreRepository#READONLY_SETTING_KEY` constant to reduce this
trappiness.

plugins/repository-azure/src/main/java/org/elasticsearch/repositories/azure/AzureRepository.java

@@ -71,7 +71,7 @@ public static final class Repository {
         public static final Setting<ByteSizeValue> CHUNK_SIZE_SETTING =
             Setting.byteSizeSetting("chunk_size", MAX_CHUNK_SIZE, MIN_CHUNK_SIZE, MAX_CHUNK_SIZE, Property.NodeScope);
         public static final Setting<Boolean> COMPRESS_SETTING = Setting.boolSetting("compress", false, Property.NodeScope);
-        public static final Setting<Boolean> READONLY_SETTING = Setting.boolSetting("readonly", false, Property.NodeScope);
+        public static final Setting<Boolean> READONLY_SETTING = Setting.boolSetting(READONLY_SETTING_KEY, false, Property.NodeScope);
     }
 
     private final BlobPath basePath;

plugins/repository-azure/src/test/java/org/elasticsearch/repositories/azure/AzureRepositorySettingsTests.java

@@ -31,6 +31,7 @@
 import org.elasticsearch.repositories.blobstore.BlobStoreTestUtil;
 import org.elasticsearch.test.ESTestCase;
 
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.nullValue;
 import static org.mockito.Mockito.mock;
@@ -57,7 +58,7 @@ public void testReadonlyDefault() {
 
     public void testReadonlyDefaultAndReadonlyOn() {
         assertThat(azureRepository(Settings.builder()
-            .put("readonly", true)
+            .put(READONLY_SETTING_KEY, true)
             .build()).isReadOnly(), is(true));
     }
 
@@ -70,35 +71,35 @@ public void testReadonlyWithPrimaryOnly() {
     public void testReadonlyWithPrimaryOnlyAndReadonlyOn() {
         assertThat(azureRepository(Settings.builder()
             .put(AzureRepository.Repository.LOCATION_MODE_SETTING.getKey(), LocationMode.PRIMARY_ONLY.name())
-            .put("readonly", true)
+            .put(READONLY_SETTING_KEY, true)
             .build()).isReadOnly(), is(true));
     }
 
     public void testReadonlyWithSecondaryOnlyAndReadonlyOn() {
         assertThat(azureRepository(Settings.builder()
             .put(AzureRepository.Repository.LOCATION_MODE_SETTING.getKey(), LocationMode.SECONDARY_ONLY.name())
-            .put("readonly", true)
+            .put(READONLY_SETTING_KEY, true)
             .build()).isReadOnly(), is(true));
     }
 
     public void testReadonlyWithSecondaryOnlyAndReadonlyOff() {
         assertThat(azureRepository(Settings.builder()
             .put(AzureRepository.Repository.LOCATION_MODE_SETTING.getKey(), LocationMode.SECONDARY_ONLY.name())
-            .put("readonly", false)
+            .put(READONLY_SETTING_KEY, false)
             .build()).isReadOnly(), is(false));
     }
 
     public void testReadonlyWithPrimaryAndSecondaryOnlyAndReadonlyOn() {
         assertThat(azureRepository(Settings.builder()
             .put(AzureRepository.Repository.LOCATION_MODE_SETTING.getKey(), LocationMode.PRIMARY_THEN_SECONDARY.name())
-            .put("readonly", true)
+            .put(READONLY_SETTING_KEY, true)
             .build()).isReadOnly(), is(true));
     }
 
     public void testReadonlyWithPrimaryAndSecondaryOnlyAndReadonlyOff() {
         assertThat(azureRepository(Settings.builder()
             .put(AzureRepository.Repository.LOCATION_MODE_SETTING.getKey(), LocationMode.PRIMARY_THEN_SECONDARY.name())
-            .put("readonly", false)
+            .put(READONLY_SETTING_KEY, false)
             .build()).isReadOnly(), is(false));
     }
 

qa/repository-multi-version/src/test/java/org/elasticsearch/upgrades/MultiVersionRepositoryAccessIT.java

@@ -47,6 +47,7 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.hamcrest.Matchers.hasItem;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.is;
@@ -285,8 +286,8 @@ private void ensureSnapshotRestoreWorks(String repoName, String name, int shards
 
     private static void createRepository(RestHighLevelClient client, String repoName, boolean readOnly) throws IOException {
         assertThat(client.snapshot().createRepository(new PutRepositoryRequest(repoName).type("fs").settings(
-            Settings.builder().put("location", "./" + repoName).put("readonly", readOnly)), RequestOptions.DEFAULT).isAcknowledged(),
-            is(true));
+            Settings.builder().put("location", "./" + repoName).put(READONLY_SETTING_KEY, readOnly)), RequestOptions.DEFAULT)
+                        .isAcknowledged(), is(true));
     }
 
     private static void createSnapshot(RestHighLevelClient client, String repoName, String name, String index) throws IOException {

server/src/internalClusterTest/java/org/elasticsearch/snapshots/MultiClusterRepoAccessIT.java

@@ -39,6 +39,7 @@
 import java.util.Arrays;
 import java.util.function.Function;
 
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
@@ -126,7 +127,7 @@ public void testConcurrentWipeAndRecreateFromOtherCluster() throws InterruptedEx
         secondCluster.startDataOnlyNode();
         assertAcked(secondCluster.client().admin().cluster().preparePutRepository(repoName)
                 .setType("fs")
-                .setSettings(Settings.builder().put("location", repoPath).put("readonly", true)));
+                .setSettings(Settings.builder().put("location", repoPath).put(READONLY_SETTING_KEY, true)));
         assertThat(secondCluster.client().admin().cluster().prepareGetRepositories(repoName).get().repositories()
                 .stream().filter(r -> r.name().equals(repoName)).findFirst().get().uuid(), equalTo(repoUuid));
 

server/src/internalClusterTest/java/org/elasticsearch/snapshots/RepositoriesIT.java

@@ -36,6 +36,7 @@
 import java.nio.file.Path;
 import java.util.List;
 
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertRequestBuilderThrows;
 import static org.hamcrest.Matchers.containsString;
@@ -183,7 +184,7 @@ public void testRepositoryVerification() throws Exception {
                 .put("location", randomRepoPath())
                 .put("random_control_io_exception_rate", 1.0).build();
         Settings readonlySettings = Settings.builder().put(settings)
-            .put("readonly", true).build();
+            .put(READONLY_SETTING_KEY, true).build();
         logger.info("-->  creating repository that cannot write any files - should fail");
         assertRequestBuilderThrows(client.admin().cluster().preparePutRepository("test-repo-1")
                         .setType("mock").setSettings(settings),

server/src/internalClusterTest/java/org/elasticsearch/snapshots/SharedClusterSnapshotRestoreIT.java

@@ -91,6 +91,7 @@
 import static org.elasticsearch.index.IndexSettings.INDEX_SOFT_DELETES_SETTING;
 import static org.elasticsearch.index.shard.IndexShardTests.getEngineFromShard;
 import static org.elasticsearch.indices.recovery.RecoverySettings.INDICES_RECOVERY_MAX_BYTES_PER_SEC_SETTING;
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAllSuccessful;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertHitCount;
@@ -912,7 +913,7 @@ public void testReadonlyRepository() throws Exception {
         createRepository("readonly-repo", "fs", Settings.builder()
             .put("location", repositoryLocation)
             .put("compress", randomBoolean())
-            .put("readonly", true)
+            .put(READONLY_SETTING_KEY, true)
             .put("chunk_size", randomIntBetween(100, 1000), ByteSizeUnit.BYTES));
         logger.info("--> restore index after deletion");
         RestoreSnapshotResponse restoreSnapshotResponse = client.admin().cluster().prepareRestoreSnapshot("readonly-repo", "test-snap")

server/src/main/java/org/elasticsearch/repositories/blobstore/BlobStoreRepository.java

@@ -188,6 +188,11 @@ public abstract class BlobStoreRepository extends AbstractLifecycleComponent imp
 
     private static final String UPLOADED_DATA_BLOB_PREFIX = "__";
 
+    /**
+     * All {@link BlobStoreRepository} implementations can be made read-only by setting this key to {@code true} in their settings.
+     */
+    public static final String READONLY_SETTING_KEY = "readonly";
+
     /**
      * Prefix used for the identifiers of data blobs that were not actually written to the repository physically because their contents are
      * already stored in the metadata referencing them, i.e. in {@link BlobStoreIndexShardSnapshot} and
@@ -337,7 +342,7 @@ protected BlobStoreRepository(
         this.supportURLRepo = SUPPORT_URL_REPO.get(metadata.settings());
         snapshotRateLimiter = getRateLimiter(metadata.settings(), "max_snapshot_bytes_per_sec", new ByteSizeValue(40, ByteSizeUnit.MB));
         restoreRateLimiter = getRateLimiter(metadata.settings(), "max_restore_bytes_per_sec", ByteSizeValue.ZERO);
-        readOnly = metadata.settings().getAsBoolean("readonly", false);
+        readOnly = metadata.settings().getAsBoolean(READONLY_SETTING_KEY, false);
         cacheRepositoryData = CACHE_REPOSITORY_DATA.get(metadata.settings());
         bufferSize = Math.toIntExact(BUFFER_SIZE_SETTING.get(metadata.settings()).getBytes());
         this.maxSnapshotCount = MAX_SNAPSHOTS_SETTING.get(metadata.settings());

test/framework/src/main/java/org/elasticsearch/repositories/blobstore/ESBlobStoreRepositoryIntegTestCase.java

@@ -59,6 +59,7 @@
 import java.util.Map;
 import java.util.Set;
 
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertHitCount;
 import static org.hamcrest.Matchers.equalTo;
@@ -101,7 +102,7 @@ protected final String createRepository(final String name, final Settings settin
         internalCluster().getDataOrMasterNodeInstances(RepositoriesService.class).forEach(repositories -> {
             assertThat(repositories.repository(name), notNullValue());
             assertThat(repositories.repository(name), instanceOf(BlobStoreRepository.class));
-            assertThat(repositories.repository(name).isReadOnly(), is(settings.getAsBoolean("readonly", false)));
+            assertThat(repositories.repository(name).isReadOnly(), is(settings.getAsBoolean(READONLY_SETTING_KEY, false)));
             BlobStore blobStore = ((BlobStoreRepository) repositories.repository(name)).getBlobStore();
             assertThat("blob store has to be lazy initialized", blobStore, verify ? is(notNullValue()) : is(nullValue()));
         });

test/framework/src/main/java/org/elasticsearch/repositories/blobstore/ESFsBasedRepositoryIntegTestCase.java

@@ -33,6 +33,7 @@
 import java.nio.file.Path;
 import java.util.stream.Stream;
 
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertHitCount;
 import static org.hamcrest.Matchers.instanceOf;
@@ -76,7 +77,7 @@ public void testMissingDirectoriesNotCreatedInReadonlyRepository() throws IOExce
         }
         assertFalse(Files.exists(deletedPath));
 
-        createRepository(repoName, Settings.builder().put(repoSettings).put("readonly", true).build(), randomBoolean());
+        createRepository(repoName, Settings.builder().put(repoSettings).put(READONLY_SETTING_KEY, true).build(), randomBoolean());
 
         final ElasticsearchException exception = expectThrows(ElasticsearchException.class, () ->
             client().admin().cluster().prepareRestoreSnapshot(repoName, snapshotName).setWaitForCompletion(randomBoolean()).get());
@@ -90,7 +91,7 @@ public void testReadOnly() throws Exception {
         final Path repoPath = randomRepoPath();
         final Settings repoSettings = Settings.builder()
                 .put(repositorySettings(repoName))
-                .put("readonly", true)
+                .put(READONLY_SETTING_KEY, true)
                 .put(FsRepository.LOCATION_SETTING.getKey(), repoPath)
                 .put(BlobStoreRepository.BUFFER_SIZE_SETTING.getKey(), String.valueOf(randomIntBetween(1, 8) * 1024) + "kb")
                 .build();
@@ -107,7 +108,7 @@ public void testReadOnly() throws Exception {
             assertFalse(Files.exists(storePath));
         }
 
-        createRepository(repoName, Settings.builder().put(repoSettings).put("readonly", false).build(), false);
+        createRepository(repoName, Settings.builder().put(repoSettings).put(READONLY_SETTING_KEY, false).build(), false);
 
         try (BlobStore store = newBlobStore(repoName)) {
             assertTrue(Files.exists(repoPath));

test/framework/src/main/java/org/elasticsearch/snapshots/AbstractSnapshotIntegTestCase.java

@@ -89,6 +89,7 @@
 import java.util.function.Predicate;
 import java.util.stream.StreamSupport;
 
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.equalTo;
@@ -139,7 +140,7 @@ public void assertRepoConsistency() {
         if (skipRepoConsistencyCheckReason == null) {
             clusterAdmin().prepareGetRepositories().get().repositories().forEach(repositoryMetadata -> {
                 final String name = repositoryMetadata.name();
-                if (repositoryMetadata.settings().getAsBoolean("readonly", false) == false) {
+                if (repositoryMetadata.settings().getAsBoolean(READONLY_SETTING_KEY, false) == false) {
                     clusterAdmin().prepareDeleteSnapshot(name, OLD_VERSION_SNAPSHOT_PREFIX + "*").get();
                     clusterAdmin().prepareCleanupRepository(name).get();
                 }

x-pack/plugin/repository-encrypted/src/internalClusterTest/java/org/elasticsearch/repositories/encrypted/EncryptedFSBlobStoreRepositoryIntegTests.java

@@ -33,6 +33,7 @@
 import java.util.Locale;
 import java.util.stream.Stream;
 
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.elasticsearch.repositories.encrypted.EncryptedRepository.getEncryptedBlobByteLength;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.containsString;
@@ -137,7 +138,7 @@ public void testTamperedEncryptionMetadata() throws Exception {
             });
         }
 
-        final Settings settings = Settings.builder().put(repoSettings).put("readonly", randomBoolean()).build();
+        final Settings settings = Settings.builder().put(repoSettings).put(READONLY_SETTING_KEY, randomBoolean()).build();
         final boolean verifyOnCreate = randomBoolean();
 
         if (verifyOnCreate) {

x-pack/plugin/repository-encrypted/src/internalClusterTest/java/org/elasticsearch/repositories/encrypted/EncryptedRepositorySecretIntegTests.java

@@ -46,6 +46,7 @@
 import java.util.stream.Collectors;
 
 import static org.elasticsearch.cluster.metadata.IndexMetadata.SETTING_NUMBER_OF_SHARDS;
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertHitCount;
 import static org.hamcrest.Matchers.contains;
@@ -740,7 +741,7 @@ protected String createRepository(final String name, final Settings settings, fi
         internalCluster().getDataOrMasterNodeInstances(RepositoriesService.class).forEach(repositories -> {
             assertThat(repositories.repository(name), notNullValue());
             assertThat(repositories.repository(name), instanceOf(BlobStoreRepository.class));
-            assertThat(repositories.repository(name).isReadOnly(), is(settings.getAsBoolean("readonly", false)));
+            assertThat(repositories.repository(name).isReadOnly(), is(settings.getAsBoolean(READONLY_SETTING_KEY, false)));
         });
 
         return name;

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsIntegTests.java

@@ -86,6 +86,7 @@
 import static org.elasticsearch.cluster.metadata.IndexMetadata.INDEX_NUMBER_OF_SHARDS_SETTING;
 import static org.elasticsearch.index.IndexSettings.INDEX_SOFT_DELETES_SETTING;
 import static org.elasticsearch.index.query.QueryBuilders.matchQuery;
+import static org.elasticsearch.repositories.blobstore.BlobStoreRepository.READONLY_SETTING_KEY;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertHitCount;
 import static org.elasticsearch.xpack.searchablesnapshots.SearchableSnapshots.DATA_TIERS_PREFERENCE;
@@ -942,7 +943,7 @@ public void testSnapshotOfSearchableSnapshotIncludesNoDataButCanBeRestored() thr
             assertAcked(client().admin().cluster().prepareDeleteRepository(repositoryName));
             final Settings.Builder settings = Settings.builder().put(repositoryMetadata.settings());
             if (randomBoolean()) {
-                settings.put("readonly", "true");
+                settings.put(READONLY_SETTING_KEY, "true");
             }
             assertAcked(
                 clusterAdmin().preparePutRepository(newRepositoryName)