cat API: added endpoint for Circuit Breakers

docs/changelog/136890.yaml

@@ -0,0 +1,5 @@
+pr: 136890
+summary: "Cat API: added endpoint for Circuit Breakers"
+area: Infra/REST API
+type: enhancement
+issues: []

rest-api-spec/src/main/resources/rest-api-spec/api/cat.circuit_breaker.json

@@ -0,0 +1,98 @@
+{
+  "cat.circuit_breaker": {
+    "documentation": {
+      "url": "https://www.elastic.co/docs/api/doc/elasticsearch#TODO",
+      "description": "Get circuit breakers statistics"
+    },
+    "stability": "stable",
+    "visibility": "public",
+    "headers": {
+      "accept": [
+        "text/plain",
+        "application/json"
+      ]
+    },
+    "url": {
+      "paths": [
+        {
+          "path": "/_cat/circuit_breaker",
+          "methods": [
+            "GET"
+          ]
+        },
+        {
+          "path": "/_cat/circuit_breaker/{circuit_breaker_patterns}",
+          "methods": [
+            "GET"
+          ],
+          "parts": {
+            "circuit_breaker_patterns": {
+              "type": "list",
+              "description": "A comma-separated list of regular-expressions to filter the circuit breakers in the output"
+            }
+          }
+        }
+      ]
+    },
+    "params": {
+      "format": {
+        "type": "string",
+        "default": "text",
+        "description": "a short version of the Accept header, e.g. json, yaml"
+      },
+      "time": {
+        "type": "enum",
+        "description": "The unit in which to display time values",
+        "options": [
+          "d",
+          "h",
+          "m",
+          "s",
+          "ms",
+          "micros",
+          "nanos"
+        ]
+      },
+      "local": {
+        "type": "boolean",
+        "default": false,
+        "description": "Return local information, do not retrieve the state from master node (default: false)"
+      },
+      "master_timeout": {
+        "type": "time",
+        "default": "30s",
+        "description": "Explicit operation timeout for connection to master node"
+      },
+      "h": {
+        "type": "list",
+        "description": "Comma-separated list of column names to display"
+      },
+      "help": {
+        "type": "boolean",
+        "description": "Return help information",
+        "default": false
+      },
+      "s": {
+        "type": "list",
+        "description": "Comma-separated list of column names or column aliases to sort by"
+      },
+      "v": {
+        "type": "boolean",
+        "description": "Verbose mode. Display column headers",
+        "default": false
+      },
+      "bytes": {
+        "type": "enum",
+        "description": "The unit in which to display byte values",
+        "options": [
+          "b",
+          "kb",
+          "mb",
+          "gb",
+          "tb",
+          "pb"
+        ]
+      }
+    }
+  }
+}

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/cat.circuit_breaker/10_basic.yml

@@ -0,0 +1,80 @@
+---
+"Test cat circuit_breaker help":
+  - requires:
+      capabilities:
+        - method: GET
+          path: /_cat/circuit_breaker
+      test_runner_features: capabilities
+      reason: Capability required to run test
+  - do:
+      cat.circuit_breaker:
+        help: true
+
+  - match:
+      $body: |
+               /^   node_id     .+   \n
+                    node_name   .+   \n
+                    breaker     .+   \n
+                    limit       .+   \n
+                    limit_bytes .+   \n
+                    estimated   .+   \n
+                    estimated_bytes .+   \n
+                    tripped     .+   \n
+                    overhead    .+   \n  $/
+
+---
+"Test cat circuit_breaker output":
+  - requires:
+      capabilities:
+        - method: GET
+          path: /_cat/circuit_breaker
+      test_runner_features: capabilities
+      reason: Capability required to run test
+  - do:
+      cat.circuit_breaker: {}
+
+  - match:
+      $body: |
+               /  #node_id     breaker \s+ limit      \s+ estimated  \s+ tripped  \n
+               ^  (\S+     \s+ \S+     \s+ \S+        \s+ \S+        \s+ \d+     \n)+  $/
+
+  - do:
+      cat.circuit_breaker:
+          v: true
+
+  - match:
+        $body: |
+                 /^   node_id \s+ breaker \s+ limit  \s+ estimated \s+ tripped \n
+                     (\S+   \s+ \S+      \s+ \S+    \s+ \S+      \s+ \d+     \n)+  $/
+
+  - do:
+      cat.circuit_breaker:
+          circuit_breaker_patterns: request,fielddata
+          h: node_id,breaker,limit,estimated,tripped
+          v: true
+
+  - match:
+      $body: |
+               /^  node_id \s+ breaker   \s+ limit \s+ estimated \s+ tripped \n
+                  (\S+   \s+ (request|fielddata) \s+ \S+ \s+ \S+    \s+ \d+  \n){2,}  $/
+
+  - do:
+      cat.circuit_breaker:
+          circuit_breaker_patterns: request
+          h: node_id,breaker,limit,limit_bytes,estimated,estimated_bytes,tripped,overhead
+          v: true
+
+  - match:
+      $body: |
+               /^  node_id \s+ breaker  \s+ limit   \s+ limit_bytes \s+ estimated \s+ estimated_bytes \s+ tripped \s+ overhead \n
+                  (\S+   \s+ request    \s+ \S+     \s+ \d+         \s+ \S+        \s+ \d+             \s+ \d+    \s+ \d+\.\d+ \n)+  $/
+
+  - do:
+      cat.circuit_breaker:
+          circuit_breaker_patterns: "*"
+          h: node_id,breaker,tripped
+
+  - match:
+      $body: |
+               /  #node_id     breaker   \s+ tripped  \n
+               ^  (\S+     \s+ \S+     \s+ \d+     \n)+  $/

server/src/main/java/org/elasticsearch/action/ActionModule.java

@@ -376,6 +376,7 @@
 import org.elasticsearch.rest.action.cat.RestAliasAction;
 import org.elasticsearch.rest.action.cat.RestAllocationAction;
 import org.elasticsearch.rest.action.cat.RestCatAction;
+import org.elasticsearch.rest.action.cat.RestCatCircuitBreakerAction;
 import org.elasticsearch.rest.action.cat.RestCatComponentTemplateAction;
 import org.elasticsearch.rest.action.cat.RestCatRecoveryAction;
 import org.elasticsearch.rest.action.cat.RestFielddataAction;
@@ -1028,6 +1029,7 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster, Predicate<
         registerHandler.accept(new org.elasticsearch.rest.action.cat.RestPendingClusterTasksAction());
         registerHandler.accept(new RestAliasAction());
         registerHandler.accept(new RestThreadPoolAction());
+        registerHandler.accept(new RestCatCircuitBreakerAction());
         registerHandler.accept(new RestPluginsAction());
         registerHandler.accept(new RestFielddataAction());
         registerHandler.accept(new RestNodeAttrsAction());

server/src/main/java/org/elasticsearch/rest/action/cat/RestCatCircuitBreakerAction.java

@@ -0,0 +1,136 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.rest.action.cat;
+
+import org.elasticsearch.action.FailedNodeException;
+import org.elasticsearch.action.admin.cluster.node.stats.NodeStats;
+import org.elasticsearch.action.admin.cluster.node.stats.NodesStatsRequest;
+import org.elasticsearch.action.admin.cluster.node.stats.NodesStatsRequestParameters;
+import org.elasticsearch.action.admin.cluster.node.stats.NodesStatsResponse;
+import org.elasticsearch.client.internal.node.NodeClient;
+import org.elasticsearch.common.Table;
+import org.elasticsearch.common.regex.Regex;
+import org.elasticsearch.common.unit.ByteSizeValue;
+import org.elasticsearch.indices.breaker.CircuitBreakerStats;
+import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.RestResponse;
+import org.elasticsearch.rest.Scope;
+import org.elasticsearch.rest.ServerlessScope;
+import org.elasticsearch.rest.action.RestResponseListener;
+
+import java.util.List;
+import java.util.Set;
+
+import static org.elasticsearch.common.util.set.Sets.addToCopy;
+import static org.elasticsearch.rest.RestRequest.Method.GET;
+
+@ServerlessScope(Scope.INTERNAL)
+public class RestCatCircuitBreakerAction extends AbstractCatAction {
+
+    private static final Set<String> RESPONSE_PARAMS = addToCopy(AbstractCatAction.RESPONSE_PARAMS, "circuit_breaker_patterns");
+
+    @Override
+    public String getName() {
+        return "cat_circuitbreaker_action";
+    }
+
+    @Override
+    public List<Route> routes() {
+        return List.of(new Route(GET, "/_cat/circuit_breaker"), new Route(GET, "/_cat/circuit_breaker/{circuit_breaker_patterns}"));
+    }
+
+    @Override
+    protected void documentation(StringBuilder sb) {
+        sb.append("/_cat/circuit_breaker\n");
+        sb.append("/_cat/circuit_breaker/{circuit_breaker_patterns}\n");
+    }
+
+    @Override
+    protected Set<String> responseParams() {
+        return RESPONSE_PARAMS;
+    }
+
+    @Override
+    protected RestChannelConsumer doCatRequest(RestRequest request, NodeClient client) {
+        NodesStatsRequest nodesStatsRequest = new NodesStatsRequest(); // Empty nodes array sends request to all nodes.
+        nodesStatsRequest.clear().addMetric(NodesStatsRequestParameters.Metric.BREAKER);
+
+        return channel -> client.admin().cluster().nodesStats(nodesStatsRequest, new RestResponseListener<>(channel) {
+            @Override
+            public RestResponse buildResponse(final NodesStatsResponse nodesStatsResponse) throws Exception {
+                RestResponse response = RestTable.buildResponse(buildTable(request, nodesStatsResponse), channel);
+                if (nodesStatsResponse.failures().isEmpty() == false) {
+                    response.addHeader("Warning", "Partial success, missing info from " + nodesStatsResponse.failures().size() + " nodes.");
+                }
+                return response;
+            }
+        });
+    }
+
+    @Override
+    protected Table getTableWithHeader(RestRequest request) {
+        Table table = new Table();
+        table.startHeaders();
+        table.addCell("node_id", "default:true;alias:id;desc:persistent node id");
+        table.addCell("node_name", "default:false;alias:nn;desc:node name");
+        table.addCell("breaker", "default:true;alias:br;desc:breaker name");
+        table.addCell("limit", "default:true;alias:l;desc:limit size");
+        table.addCell("limit_bytes", "default:false;alias:lb;desc:limit size in bytes");
+        table.addCell("estimated", "default:true;alias:e;desc:estimated size");
+        table.addCell("estimated_bytes", "default:false;alias:eb;desc:estimated size in bytes");
+        table.addCell("tripped", "default:true;alias:t;desc:tripped count");
+        table.addCell("overhead", "default:false;alias:o;desc:overhead");
+        table.endHeaders();
+        return table;
+    }
+
+    private Table buildTable(RestRequest request, NodesStatsResponse nodesStatsResponse) {
+        final Table table = getTableWithHeader(request);
+        final String[] circuitBreakers = request.paramAsStringArray("circuit_breaker_patterns", new String[] { "*" });
+
+        for (final NodeStats nodeStats : nodesStatsResponse.getNodes()) {
+            if (nodeStats.getBreaker() == null) {
+                continue;
+            }
+            for (final CircuitBreakerStats circuitBreakerStats : nodeStats.getBreaker().getAllStats()) {
+                if (Regex.simpleMatch(circuitBreakers, circuitBreakerStats.getName()) == false) {
+                    continue;
+                }
+                table.startRow();
+                table.addCell(nodeStats.getNode().getId());
+                table.addCell(nodeStats.getNode().getName());
+                table.addCell(circuitBreakerStats.getName());
+                table.addCell(ByteSizeValue.ofBytes(circuitBreakerStats.getLimit()));
+                table.addCell(circuitBreakerStats.getLimit());
+                table.addCell(ByteSizeValue.ofBytes(circuitBreakerStats.getEstimated()));
+                table.addCell(circuitBreakerStats.getEstimated());
+                table.addCell(circuitBreakerStats.getTrippedCount());
+                table.addCell(circuitBreakerStats.getOverhead());
+                table.endRow();
+            }
+        }
+
+        for (final FailedNodeException errors : nodesStatsResponse.failures()) {
+            table.startRow();
+            table.addCell(errors.nodeId());
+            table.addCell("N/A");
+            table.addCell(errors.getMessage());
+            table.addCell("N/A");
+            table.addCell("N/A");
+            table.addCell("N/A");
+            table.addCell("N/A");
+            table.addCell("N/A");
+            table.addCell("N/A");
+            table.endRow();
+        }
+
+        return table;
+    }
+}