Add SnapshotRetentionConfiguration for retention configuration

This commit adds the `SnapshotRetentionConfiguration` class and its HLRC
counterpart to encapsulate the configuration for SLM retention.
Currently only a single parameter is supported as an example (we still
need to discuss the different options we want to support and their
names) to keep the size of the PR down. It also does not yet include version serialization checks
since the original SLM branch has not yet been merged.

Relates to elastic#43663

client/rest-high-level/src/main/java/org/elasticsearch/client/snapshotlifecycle/SnapshotLifecyclePolicy.java

@@ -38,11 +38,13 @@ public class SnapshotLifecyclePolicy implements ToXContentObject {
     private final String schedule;
     private final String repository;
     private final Map<String, Object> configuration;
+    private final SnapshotRetentionConfiguration retentionPolicy;
 
     private static final ParseField NAME = new ParseField("name");
     private static final ParseField SCHEDULE = new ParseField("schedule");
     private static final ParseField REPOSITORY = new ParseField("repository");
     private static final ParseField CONFIG = new ParseField("config");
+    private static final ParseField RETENTION = new ParseField("retention");
     private static final IndexNameExpressionResolver.DateMathExpressionResolver DATE_MATH_RESOLVER =
         new IndexNameExpressionResolver.DateMathExpressionResolver();
 
@@ -54,23 +56,27 @@ public class SnapshotLifecyclePolicy implements ToXContentObject {
                 String schedule = (String) a[1];
                 String repo = (String) a[2];
                 Map<String, Object> config = (Map<String, Object>) a[3];
-                return new SnapshotLifecyclePolicy(id, name, schedule, repo, config);
+                SnapshotRetentionConfiguration retention = (SnapshotRetentionConfiguration) a[4];
+                return new SnapshotLifecyclePolicy(id, name, schedule, repo, config, retention);
             });
 
     static {
         PARSER.declareString(ConstructingObjectParser.constructorArg(), NAME);
         PARSER.declareString(ConstructingObjectParser.constructorArg(), SCHEDULE);
         PARSER.declareString(ConstructingObjectParser.constructorArg(), REPOSITORY);
         PARSER.declareObject(ConstructingObjectParser.constructorArg(), (p, c) -> p.map(), CONFIG);
+        PARSER.declareObject(ConstructingObjectParser.constructorArg(), SnapshotRetentionConfiguration::parse, RETENTION);
     }
 
     public SnapshotLifecyclePolicy(final String id, final String name, final String schedule,
-                                   final String repository, Map<String, Object> configuration) {
+                                   final String repository, Map<String, Object> configuration,
+                                   SnapshotRetentionConfiguration retentionPolicy) {
         this.id = Objects.requireNonNull(id);
         this.name = name;
         this.schedule = schedule;
         this.repository = repository;
         this.configuration = configuration;
+        this.retentionPolicy = retentionPolicy;
     }
 
     public String getId() {
@@ -93,6 +99,10 @@ public Map<String, Object> getConfig() {
         return this.configuration;
     }
 
+    public SnapshotRetentionConfiguration getRetentionPolicy() {
+        return this.retentionPolicy;
+    }
+
     public static SnapshotLifecyclePolicy parse(XContentParser parser, String id) {
         return PARSER.apply(parser, id);
     }
@@ -104,13 +114,14 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         builder.field(SCHEDULE.getPreferredName(), this.schedule);
         builder.field(REPOSITORY.getPreferredName(), this.repository);
         builder.field(CONFIG.getPreferredName(), this.configuration);
+        builder.field(RETENTION.getPreferredName(), this.retentionPolicy);
         builder.endObject();
         return builder;
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(id, name, schedule, repository, configuration);
+        return Objects.hash(id, name, schedule, repository, configuration, retentionPolicy);
     }
 
     @Override
@@ -127,7 +138,8 @@ public boolean equals(Object obj) {
             Objects.equals(name, other.name) &&
             Objects.equals(schedule, other.schedule) &&
             Objects.equals(repository, other.repository) &&
-            Objects.equals(configuration, other.configuration);
+            Objects.equals(configuration, other.configuration) &&
+            Objects.equals(retentionPolicy, other.retentionPolicy);
     }
 
     @Override

client/rest-high-level/src/main/java/org/elasticsearch/client/snapshotlifecycle/SnapshotRetentionConfiguration.java

@@ -0,0 +1,93 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.client.snapshotlifecycle;
+
+import org.elasticsearch.common.ParseField;
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.common.xcontent.ConstructingObjectParser;
+import org.elasticsearch.common.xcontent.ToXContentObject;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.common.xcontent.XContentParser;
+
+import java.io.IOException;
+import java.util.Objects;
+
+public class SnapshotRetentionConfiguration implements ToXContentObject {
+
+    public static final SnapshotRetentionConfiguration EMPTY = new SnapshotRetentionConfiguration((TimeValue) null);
+
+    private static final ParseField EXPIRE_AFTER = new ParseField("expire_after");
+
+    private static final ConstructingObjectParser<SnapshotRetentionConfiguration, Void> PARSER =
+        new ConstructingObjectParser<>("snapshot_retention", true, a -> {
+            TimeValue expireAfter = TimeValue.parseTimeValue((String) a[0], EXPIRE_AFTER.getPreferredName());
+            return new SnapshotRetentionConfiguration(expireAfter);
+        });
+
+    static {
+        PARSER.declareString(ConstructingObjectParser.optionalConstructorArg(), EXPIRE_AFTER);
+    }
+
+    // TODO: add the rest of the configuration values
+    private final TimeValue expireAfter;
+
+    public SnapshotRetentionConfiguration(TimeValue expireAfter) {
+        this.expireAfter = expireAfter;
+    }
+
+    public static SnapshotRetentionConfiguration parse(XContentParser parser, String name) {
+        return PARSER.apply(parser, null);
+    }
+
+    public TimeValue getExpireAfter() {
+        return this.expireAfter;
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        builder.startObject();
+        builder.field(EXPIRE_AFTER.getPreferredName(), expireAfter.getStringRep());
+        builder.endObject();
+        return builder;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(expireAfter);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
+        if (obj.getClass() != getClass()) {
+            return false;
+        }
+        SnapshotRetentionConfiguration other = (SnapshotRetentionConfiguration) obj;
+        return this.expireAfter.equals(other.expireAfter);
+    }
+
+    @Override
+    public String toString() {
+        return Strings.toString(this);
+    }
+}

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/ILMDocumentationIT.java

@@ -63,6 +63,7 @@
 import org.elasticsearch.client.snapshotlifecycle.SnapshotInvocationRecord;
 import org.elasticsearch.client.snapshotlifecycle.SnapshotLifecyclePolicy;
 import org.elasticsearch.client.snapshotlifecycle.SnapshotLifecyclePolicyMetadata;
+import org.elasticsearch.client.snapshotlifecycle.SnapshotRetentionConfiguration;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.collect.ImmutableOpenMap;
@@ -773,8 +774,11 @@ public void testAddSnapshotLifecyclePolicy() throws Exception {
         // tag::slm-put-snapshot-lifecycle-policy
         Map<String, Object> config = new HashMap<>();
         config.put("indices", Collections.singletonList("idx"));
+        SnapshotRetentionConfiguration retention =
+            new SnapshotRetentionConfiguration(TimeValue.timeValueDays(30));
         SnapshotLifecyclePolicy policy = new SnapshotLifecyclePolicy(
-            "policy_id", "name", "1 2 3 * * ?", "my_repository", config);
+            "policy_id", "name", "1 2 3 * * ?",
+            "my_repository", config, retention);
         PutSnapshotLifecyclePolicyRequest request =
             new PutSnapshotLifecyclePolicyRequest(policy);
         // end::slm-put-snapshot-lifecycle-policy

libs/core/src/main/java/org/elasticsearch/common/unit/TimeValue.java

@@ -71,6 +71,14 @@ public static TimeValue timeValueHours(long hours) {
         return new TimeValue(hours, TimeUnit.HOURS);
     }
 
+    public static TimeValue timeValueDays(long days) {
+        // 106751.9 days is Long.MAX_VALUE nanoseconds, so we cannot store 106752 days
+        if (days > 106751) {
+            throw new IllegalArgumentException("time value cannot store values greater than 106751 days");
+        }
+        return new TimeValue(days, TimeUnit.DAYS);
+    }
+
     /**
      * @return the unit used for the this time value, see {@link #duration()}
      */

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/snapshotlifecycle/SnapshotLifecyclePolicy.java

@@ -51,11 +51,13 @@ public class SnapshotLifecyclePolicy extends AbstractDiffable<SnapshotLifecycleP
     private final String schedule;
     private final String repository;
     private final Map<String, Object> configuration;
+    private final SnapshotRetentionConfiguration retentionPolicy;
 
     private static final ParseField NAME = new ParseField("name");
     private static final ParseField SCHEDULE = new ParseField("schedule");
     private static final ParseField REPOSITORY = new ParseField("repository");
     private static final ParseField CONFIG = new ParseField("config");
+    private static final ParseField RETENTION = new ParseField("retention");
     private static final IndexNameExpressionResolver.DateMathExpressionResolver DATE_MATH_RESOLVER =
         new IndexNameExpressionResolver.DateMathExpressionResolver();
     private static final String POLICY_ID_METADATA_FIELD = "policy";
@@ -69,23 +71,27 @@ public class SnapshotLifecyclePolicy extends AbstractDiffable<SnapshotLifecycleP
                 String schedule = (String) a[1];
                 String repo = (String) a[2];
                 Map<String, Object> config = (Map<String, Object>) a[3];
-                return new SnapshotLifecyclePolicy(id, name, schedule, repo, config);
+                SnapshotRetentionConfiguration retention = (SnapshotRetentionConfiguration) a[4];
+                return new SnapshotLifecyclePolicy(id, name, schedule, repo, config, retention);
             });
 
     static {
         PARSER.declareString(ConstructingObjectParser.constructorArg(), NAME);
         PARSER.declareString(ConstructingObjectParser.constructorArg(), SCHEDULE);
         PARSER.declareString(ConstructingObjectParser.constructorArg(), REPOSITORY);
         PARSER.declareObject(ConstructingObjectParser.constructorArg(), (p, c) -> p.map(), CONFIG);
+        PARSER.declareObject(ConstructingObjectParser.constructorArg(), SnapshotRetentionConfiguration::parse, RETENTION);
     }
 
     public SnapshotLifecyclePolicy(final String id, final String name, final String schedule,
-                                   final String repository, Map<String, Object> configuration) {
+                                   final String repository, Map<String, Object> configuration,
+                                   SnapshotRetentionConfiguration retentionPolicy) {
         this.id = Objects.requireNonNull(id);
         this.name = name;
         this.schedule = schedule;
         this.repository = repository;
         this.configuration = configuration;
+        this.retentionPolicy = retentionPolicy;
     }
 
     public SnapshotLifecyclePolicy(StreamInput in) throws IOException {
@@ -94,6 +100,7 @@ public SnapshotLifecyclePolicy(StreamInput in) throws IOException {
         this.schedule = in.readString();
         this.repository = in.readString();
         this.configuration = in.readMap();
+        this.retentionPolicy = new SnapshotRetentionConfiguration(in);
     }
 
     public String getId() {
@@ -116,6 +123,10 @@ public Map<String, Object> getConfig() {
         return this.configuration;
     }
 
+    public SnapshotRetentionConfiguration getRetentionPolicy() {
+        return this.retentionPolicy;
+    }
+
     public long calculateNextExecution() {
         final Cron schedule = new Cron(this.schedule);
         return schedule.getNextValidTimeAfter(System.currentTimeMillis());
@@ -257,6 +268,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeString(this.schedule);
         out.writeString(this.repository);
         out.writeMap(this.configuration);
+        this.retentionPolicy.writeTo(out);
     }
 
     @Override
@@ -266,13 +278,14 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         builder.field(SCHEDULE.getPreferredName(), this.schedule);
         builder.field(REPOSITORY.getPreferredName(), this.repository);
         builder.field(CONFIG.getPreferredName(), this.configuration);
+        builder.field(RETENTION.getPreferredName(), this.retentionPolicy);
         builder.endObject();
         return builder;
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(id, name, schedule, repository, configuration);
+        return Objects.hash(id, name, schedule, repository, configuration, retentionPolicy);
     }
 
     @Override
@@ -289,7 +302,8 @@ public boolean equals(Object obj) {
             Objects.equals(name, other.name) &&
             Objects.equals(schedule, other.schedule) &&
             Objects.equals(repository, other.repository) &&
-            Objects.equals(configuration, other.configuration);
+            Objects.equals(configuration, other.configuration) &&
+            Objects.equals(retentionPolicy, other.retentionPolicy);
     }
 
     @Override