Introduce formal node ML role (#45174)

This commit builds on the ability for plugins to introduce new roles to
add a formal node ML role.

distribution/docker/src/test/resources/rest-api-spec/test/11_nodes.yml

@@ -6,8 +6,8 @@
 
   - match:
       $body: |
-        /  #ip                          heap.percent        ram.percent     cpu         load_1m                load_5m                load_15m               node.role          master          name
-        ^  ((\d{1,3}\.){3}\d{1,3}  \s+  \d+            \s+  \d*         \s+ (-)?\d* \s+ ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)?\s+  ((-)?\d*(\.\d+)?)? \s+ (-|[dmi]{1,3}) \s+ [-*x]     \s+   (\S+\s?)+     \n)+  $/
+        /  #ip                          heap.percent        ram.percent     cpu         load_1m                load_5m                load_15m               node.role           master          name
+        ^  ((\d{1,3}\.){3}\d{1,3}  \s+  \d+            \s+  \d*         \s+ (-)?\d* \s+ ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)?\s+  ((-)?\d*(\.\d+)?)? \s+ (-|[dilm]{1,4}) \s+ [-*x]     \s+   (\S+\s?)+     \n)+  $/
 
   - do:
       cat.nodes:
@@ -15,8 +15,8 @@
 
   - match:
       $body: |
-        /^  ip                     \s+  heap\.percent   \s+  ram\.percent \s+ cpu      \s+ load_1m            \s+ load_5m            \s+ load_15m           \s+ node\.role     \s+  master   \s+   name  \n
-           ((\d{1,3}\.){3}\d{1,3}  \s+  \d+             \s+  \d*          \s+ (-)?\d* \s+  ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)? \s+ (-|[dmi]{1,3}) \s+  [-*x]    \s+   (\S+\s?)+     \n)+  $/
+        /^  ip                     \s+  heap\.percent   \s+  ram\.percent \s+ cpu      \s+ load_1m            \s+ load_5m            \s+ load_15m           \s+ node\.role      \s+  master   \s+   name  \n
+           ((\d{1,3}\.){3}\d{1,3}  \s+  \d+             \s+  \d*          \s+ (-)?\d* \s+  ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)? \s+ (-|[dilm]{1,4}) \s+  [-*x]    \s+   (\S+\s?)+     \n)+  $/
 
   - do:
       cat.nodes:

docs/reference/cat/nodes.asciidoc

@@ -18,7 +18,7 @@ ip        heap.percent ram.percent cpu load_1m load_5m load_15m node.role master
 --------------------------------------------------
 // TESTRESPONSE[s/3.07/(\\d+\\.\\d+( \\d+\\.\\d+ (\\d+\\.\\d+)?)?)?/]
 // TESTRESPONSE[s/65          99  42/\\d+ \\d+ \\d+/]
-// TESTRESPONSE[s/[*]/[*]/ s/mJw06l1/.+/ non_json]
+// TESTRESPONSE[s/dim/.+/ s/[*]/[*]/ s/mJw06l1/.+/ non_json]
 
 The first few columns (`ip`, `heap.percent`, `ram.percent`, `cpu`, `load_*`) tell
 you where your nodes live and give a quick picture of performance stats.

docs/reference/getting-started.asciidoc

@@ -247,10 +247,10 @@ And the response:
 [source,txt]
 --------------------------------------------------
 ip        heap.percent ram.percent cpu load_1m load_5m load_15m node.role master name
-127.0.0.1           10           5   5    4.46                        dim      *      PB2SGZY
+127.0.0.1           10           5   5    4.46                  dim       *      PB2SGZY
 --------------------------------------------------
 // TESTRESPONSE[s/10           5   5    4.46/\\d+ \\d+ \\d+ (\\d+\\.\\d+)? (\\d+\\.\\d+)? (\\d+\.\\d+)?/]
-// TESTRESPONSE[s/[*]/[*]/ s/PB2SGZY/.+/ non_json]
+// TESTRESPONSE[s/dim/.+/ s/[*]/[*]/ s/PB2SGZY/.+/ non_json]
 
 Here, we can see our one node named "PB2SGZY", which is the single node that is currently in our cluster.
 

rest-api-spec/src/main/resources/rest-api-spec/test/cat.nodes/10_basic.yml

@@ -6,8 +6,8 @@
 
   - match:
       $body: |
-               /  #ip                          heap.percent        ram.percent     cpu         load_1m                load_5m                load_15m               node.role          master          name
-               ^  ((\d{1,3}\.){3}\d{1,3}  \s+  \d+            \s+  \d*         \s+ (-)?\d* \s+ ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)?\s+  ((-)?\d*(\.\d+)?)? \s+ (-|[dmi]{1,3}) \s+ [-*x]     \s+   (\S+\s?)+     \n)+  $/
+               /  #ip                          heap.percent        ram.percent     cpu         load_1m                load_5m                load_15m               node.role           master          name
+               ^  ((\d{1,3}\.){3}\d{1,3}  \s+  \d+            \s+  \d*         \s+ (-)?\d* \s+ ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)?\s+  ((-)?\d*(\.\d+)?)? \s+ (-|[dilm]{1,4}) \s+ [-*x]     \s+   (\S+\s?)+     \n)+  $/
 
   - do:
       cat.nodes:
@@ -15,8 +15,8 @@
 
   - match:
       $body: |
-               /^  ip                     \s+  heap\.percent   \s+  ram\.percent \s+ cpu      \s+ load_1m            \s+ load_5m            \s+ load_15m           \s+ node\.role     \s+  master   \s+   name  \n
-                  ((\d{1,3}\.){3}\d{1,3}  \s+  \d+             \s+  \d*          \s+ (-)?\d* \s+  ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)? \s+ (-|[dmi]{1,3}) \s+  [-*x]    \s+   (\S+\s?)+     \n)+  $/
+               /^  ip                     \s+  heap\.percent   \s+  ram\.percent \s+ cpu      \s+ load_1m            \s+ load_5m            \s+ load_15m           \s+ node\.role      \s+  master   \s+   name  \n
+                  ((\d{1,3}\.){3}\d{1,3}  \s+  \d+             \s+  \d*          \s+ (-)?\d* \s+  ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)? \s+ ((-)?\d*(\.\d+)?)? \s+ (-|[dilm]{1,4}) \s+  [-*x]    \s+   (\S+\s?)+     \n)+  $/
 
   - do:
       cat.nodes:

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java

@@ -19,6 +19,7 @@ import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
 import org.elasticsearch.cluster.metadata.IndexTemplateMetaData;
 import org.elasticsearch.cluster.node.DiscoveryNode;
+import org.elasticsearch.cluster.node.DiscoveryNodeRole;
 import org.elasticsearch.cluster.node.DiscoveryNodes;
 import org.elasticsearch.cluster.routing.UnassignedInfo;
 import org.elasticsearch.cluster.service.ClusterService;
@@ -280,6 +281,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 
@@ -300,6 +302,21 @@ public class MachineLearning extends Plugin implements ActionPlugin, AnalysisPlu
 
     public static final Setting<Boolean> ML_ENABLED =
             Setting.boolSetting("node.ml", XPackSettings.MACHINE_LEARNING_ENABLED, Property.NodeScope);
+
+    public static final DiscoveryNodeRole ML_ROLE = new DiscoveryNodeRole("ml", "l") {
+
+        @Override
+        protected Setting<Boolean> roleSetting() {
+            return ML_ENABLED;
+        }
+
+    };
+
+    @Override
+    public Set<DiscoveryNodeRole> getRoles() {
+        return Collections.singleton(ML_ROLE);
+    }
+
     // This is not used in v7 and higher, but users are still prevented from setting it directly to avoid confusion
     private static final String PRE_V7_ML_ENABLED_NODE_ATTR = "ml.enabled";
     public static final String MAX_OPEN_JOBS_NODE_ATTR = "ml.max_open_jobs";

x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/job/JobNodeSelectorTests.java

@@ -84,10 +84,6 @@ public class JobNodeSelectorTests extends ESTestCase {
 
         node = new DiscoveryNode(null, "_node_id1", ta, attributes, Collections.emptySet(), Version.CURRENT);
         assertEquals("{_node_id1}{ml.machine_memory=5}", JobNodeSelector.nodeNameAndMlAttributes(node));
-
-        attributes.put("node.ml", "true");
-        node = new DiscoveryNode("_node_name1", "_node_id1", ta, attributes, Collections.emptySet(), Version.CURRENT);
-        assertEquals("{_node_name1}{ml.machine_memory=5}{node.ml=true}", JobNodeSelector.nodeNameAndMlAttributes(node));
     }
 
     public void testSelectLeastLoadedMlNode_byCount() {