Remove host from cat nodes API

As the host and ip fields are always equal by design, the host field in
the cat nodes API is redundant and should be removed.

Closes #16656

core/src/main/java/org/elasticsearch/rest/action/cat/RestNodesAction.java

@@ -115,7 +115,6 @@ public class RestNodesAction extends AbstractCatAction {
         table.startHeaders();
         table.addCell("id", "default:false;alias:id,nodeId;desc:unique node id");
         table.addCell("pid", "default:false;alias:p;desc:process id");
-        table.addCell("host", "alias:h;desc:host name");
         table.addCell("ip", "alias:i;desc:ip address");
         table.addCell("port", "default:false;alias:po;desc:bound transport port");
 
@@ -242,7 +241,6 @@ public class RestNodesAction extends AbstractCatAction {
 
             table.addCell(fullId ? node.id() : Strings.substring(node.getId(), 0, 4));
             table.addCell(info == null ? null : info.getProcess().getId());
-            table.addCell(node.getHostName());
             table.addCell(node.getHostAddress());
             if (node.address() instanceof InetSocketTransportAddress) {
                 table.addCell(((InetSocketTransportAddress) node.address()).address().getPort());

docs/reference/cat/nodes.asciidoc

@@ -83,7 +83,6 @@ k0zy 192.168.56.10 9300 {version} m
 |Header |Alias |Appear by Default |Description |Example
 |`id` |`nodeId` |No |Unique node ID |k0zy
 |`pid` |`p` |No |Process ID |13061
-|`host` |`h` |Yes |Host name |n1
 |`ip` |`i` |Yes |IP address |127.0.1.1
 |`port` |`po` |No |Bound transport port |9300
 |`version` |`v` |No |Elasticsearch version |{version}

docs/reference/migration/migrate_3_0.asciidoc

@@ -173,6 +173,12 @@ header field for this purpose. Elasticsearch now uses the Accept header
 field and support for using the Content-Type header field for this
 purpose has been removed.
 
+==== Host field removed from the cat nodes API
+
+The `host` field has been removed from the cat nodes API as its value
+is always equal to the `ip` field. The `name` field is available in the
+cat nodes API and should be used instead of the `host` field.
+
 [[breaking_30_parent_child_changes]]
 === Parent/Child changes
 

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

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