[ML] Make get_job_stats robust to missing results indices (elastic/x-pack-elasticsearch#1662)

Although the job stats for jobs with missing results indices are clearly
ruined, it's better to provide zeroes for the missing values and show the
stats for other jobs than to fail the whole request. This means the UI
can continue to function.

relates elastic/x-pack-elasticsearch#1656

Original commit: elastic/x-pack-elasticsearch@a06fa994a5

plugin/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobProvider.java

@@ -180,15 +180,14 @@ public class JobProvider {
         String writeAliasName = AnomalyDetectorsIndex.resultsWriteAlias(job.getId());
         String indexName = job.getResultsIndexName();
 
-        final ActionListener<Boolean> createAliasListener = ActionListener.wrap(success -> {
+        final ActionListener<Boolean> createAliasListener = ActionListener.wrap(success ->
                     client.admin().indices().prepareAliases()
                             .addAlias(indexName, readAliasName, QueryBuilders.termQuery(Job.ID.getPreferredName(), job.getId()))
                             .addAlias(indexName, writeAliasName)
                             // we could return 'success && r.isAcknowledged()' instead of 'true', but that makes
                             // testing not possible as we can't create IndicesAliasesResponse instance or
                             // mock IndicesAliasesResponse#isAcknowledged()
-                            .execute(ActionListener.wrap(r -> finalListener.onResponse(true), finalListener::onFailure));
-                },
+                            .execute(ActionListener.wrap(r -> finalListener.onResponse(true), finalListener::onFailure)),
                 finalListener::onFailure);
 
         // Indices can be shared, so only create if it doesn't exist already. Saves us a roundtrip if
@@ -295,6 +294,7 @@ public class JobProvider {
     private SearchRequestBuilder createLatestDataCountsSearch(String indexName, String jobId) {
         return client.prepareSearch(indexName)
                 .setSize(1)
+                .setIndicesOptions(IndicesOptions.lenientExpandOpen())
                 // look for both old and new formats
                 .setQuery(QueryBuilders.idsQuery().addIds(DataCounts.documentId(jobId), DataCounts.v54DocumentId(jobId)))
                 .addSort(SortBuilders.fieldSort(DataCounts.LATEST_RECORD_TIME.getPreferredName()).order(SortOrder.DESC));
@@ -482,15 +482,13 @@ public class JobProvider {
             } else {
                 handler.accept(buckets);
             }
-        }, e -> { errorHandler.accept(mapAuthFailure(e, jobId, GetBucketsAction.NAME)); }));
+        }, e -> errorHandler.accept(mapAuthFailure(e, jobId, GetBucketsAction.NAME))));
     }
 
     private void expandBuckets(String jobId, BucketsQuery query, QueryPage<Bucket> buckets, Iterator<Bucket> bucketsToExpand,
                                Consumer<QueryPage<Bucket>> handler, Consumer<Exception> errorHandler, Client client) {
         if (bucketsToExpand.hasNext()) {
-            Consumer<Integer> c = i -> {
-                expandBuckets(jobId, query, buckets, bucketsToExpand, handler, errorHandler, client);
-            };
+            Consumer<Integer> c = i -> expandBuckets(jobId, query, buckets, bucketsToExpand, handler, errorHandler, client);
             expandBucket(jobId, query.isIncludeInterim(), bucketsToExpand.next(), query.getPartitionValue(), c, errorHandler, client);
         } else {
             handler.accept(buckets);
@@ -750,7 +748,7 @@ public class JobProvider {
         String resultsIndex = AnomalyDetectorsIndex.jobResultsAliasedName(jobId);
         SearchRequestBuilder search = createDocIdSearch(resultsIndex, ModelSnapshot.documentId(jobId, modelSnapshotId));
         searchSingleResult(jobId, ModelSnapshot.TYPE.getPreferredName(), search, ModelSnapshot.PARSER,
-                result -> handler.accept(result.result == null ? null : new Result(result.index, result.result.build())),
+                result -> handler.accept(result.result == null ? null : new Result<ModelSnapshot>(result.index, result.result.build())),
                 errorHandler, () -> null);
     }
 
@@ -953,9 +951,9 @@ public class JobProvider {
                     SearchHit[] hits = response.getHits().getHits();
                     if (hits.length == 0) {
                         LOGGER.trace("No {} for job with id {}", resultDescription, jobId);
-                        handler.accept(new Result(null, notFoundSupplier.get()));
+                        handler.accept(new Result<>(null, notFoundSupplier.get()));
                     } else if (hits.length == 1) {
-                        handler.accept(new Result(hits[0].getIndex(), parseSearchHit(hits[0], objectParser, errorHandler)));
+                        handler.accept(new Result<>(hits[0].getIndex(), parseSearchHit(hits[0], objectParser, errorHandler)));
                     } else {
                         errorHandler.accept(new IllegalStateException("Search for unique [" + resultDescription + "] returned ["
                                 + hits.length + "] hits even though size was 1"));
@@ -967,6 +965,7 @@ public class JobProvider {
     private SearchRequestBuilder createLatestModelSizeStatsSearch(String indexName) {
         return client.prepareSearch(indexName)
                 .setSize(1)
+                .setIndicesOptions(IndicesOptions.lenientExpandOpen())
                 .setQuery(QueryBuilders.termQuery(Result.RESULT_TYPE.getPreferredName(), ModelSizeStats.RESULT_TYPE_VALUE))
                 .addSort(SortBuilders.fieldSort(ModelSizeStats.LOG_TIME_FIELD.getPreferredName()).order(SortOrder.DESC));
     }

plugin/src/test/resources/rest-api-spec/test/ml/jobs_get_stats.yml

@@ -224,3 +224,47 @@ setup:
   - match: { jobs.0.job_id : job-stats-v54-bwc-test }
   - match: { jobs.0.data_counts.processed_record_count: 10 }
   - match: { jobs.0.model_size_stats.total_by_field_count: 101 }
+
+---
+"Test no exception on get job stats with missing index":
+
+  - do:
+      xpack.ml.post_data:
+        job_id: job-stats-test
+        body: >
+          {"airline":"AAL","responsetime":"132.2046","time":"1403481600"}
+          {"airline":"JZA","responsetime":"990.4628","time":"1403481600"}
+
+  - do:
+      xpack.ml.close_job:
+        job_id: jobs-get-stats-datafeed-job
+  - match: { closed: true }
+
+  - do:
+      xpack.ml.close_job:
+        job_id: job-stats-test
+  - match: { closed: true }
+
+  - do:
+      indices.delete:
+        index: .ml-anomalies-shared
+
+  - do:
+      xpack.ml.get_job_stats: {}
+  - match: { count: 2 }
+  - match: { jobs.0.data_counts.processed_record_count: 0 }
+  - match: { jobs.0.data_counts.processed_field_count: 0 }
+  - match: { jobs.0.data_counts.input_field_count: 0 }
+  - match: { jobs.0.model_size_stats.model_bytes: 0 }
+  - match: { jobs.0.state: closed }
+  - is_false: jobs.0.node
+  - is_false: jobs.0.open_time
+  - match: { jobs.1.data_counts.processed_record_count: 0 }
+  - match: { jobs.1.data_counts.processed_field_count: 0 }
+  - match: { jobs.1.data_counts.input_field_count: 0 }
+  - match: { jobs.1.model_size_stats.model_bytes: 0 }
+  - match: { jobs.1.state: closed }
+  - is_false: jobs.1.node
+  - is_false: jobs.1.open_time
+
+