Expose roles by default in cat allocation API (elastic#101753)

In elastic#96994 we added a column for node roles to the `GET _cat/allocation`
API but left it hidden by default to avoid changing behaviour. In fact
it's ok to change the behaviour of the CAT APIs since they're only
intended for human consumption, and it's awfully useful to see the node
roles in this API response, so this commit makes this column display by
default.

docs/changelog/101753.yaml

@@ -0,0 +1,5 @@
+pr: 101753
+summary: Expose roles by default in cat allocation API
+area: CAT APIs
+type: enhancement
+issues: []

docs/reference/cat/allocation.asciidoc

@@ -6,7 +6,7 @@
 
 [IMPORTANT]
 ====
-cat APIs are only intended for human consumption using the command line or {kib} 
+cat APIs are only intended for human consumption using the command line or {kib}
 console. They are _not_ intended for use by applications.
 ====
 
@@ -113,10 +113,10 @@ The API returns the following response:
 
 [source,txt]
 --------------------------------------------------
-shards disk.indices disk.used disk.avail disk.total disk.percent host      ip        node
-     1         260b    47.3gb     43.4gb    100.7gb           46 127.0.0.1 127.0.0.1 CSUXak2
+shards disk.indices disk.used disk.avail disk.total disk.percent host      ip        node    node.role
+     1         260b    47.3gb     43.4gb    100.7gb           46 127.0.0.1 127.0.0.1 CSUXak2 himrst
 --------------------------------------------------
 // TESTRESPONSE[s/\d+(\.\d+)?[tgmk]?b/\\d+(\\.\\d+)?[tgmk]?b/ s/46/\\d+/]
-// TESTRESPONSE[s/CSUXak2/.+/ non_json]
+// TESTRESPONSE[s/CSUXak2 himrst/.+/ non_json]
 
 This response shows a single shard is allocated to the one node available.

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

@@ -26,6 +26,10 @@
 ---
 "One index":
 
+  - skip:
+      version: " - 8.11.99"
+      reason:  "node.role column shown by default from 8.12.0 onwards"
+
   - do:
         indices.create:
             index: test
@@ -45,20 +49,25 @@
                 (\d+                  \s+)  #always should return value since we filter out non data nodes by default
                 [-\w.]+                \s+
                 \d+(\.\d+){3}          \s+
-                [-\w.]+
+                [-\w.]+                \s+
+                [\w]+
                 \n
               )+
               (
                 \s*                          #allow leading spaces to account for right-justified text
                 \d+                    \s+
-                UNASSIGNED
+                UNASSIGNED             \s*
                 \n
               )?
             $/
 
 ---
 "Node ID":
 
+  - skip:
+      version: " - 8.11.99"
+      reason:  "node.role column shown by default from 8.12.0 onwards"
+
   - do:
         cat.allocation:
             node_id: _master
@@ -74,7 +83,8 @@
                 (\d+                  \s+)?  #no value from client nodes
                 [-\w.]+                \s+
                 \d+(\.\d+){3}          \s+
-                [-\w.]+
+                [-\w.]+                \s+
+                [\w]+
                 \n
               )
             $/
@@ -92,6 +102,10 @@
 
 "All Nodes":
 
+   - skip:
+      version: " - 8.11.99"
+      reason:  "node.role column shown by default from 8.12.0 onwards"
+
    - do:
          cat.allocation:
            node_id: "*"
@@ -108,20 +122,25 @@
                  (\d+                  \s+)?  #no value from client nodes
                  [-\w.]+                \s+
                  \d+(\.\d+){3}          \s+
-                 [-\w.]+
+                 [-\w.]+                \s+
+                 [\w]+
                  \n
                )+
                (
                  \s*                          #allow leading spaces to account for right-justified text
                  \d+                    \s+
-                 UNASSIGNED
+                 UNASSIGNED             \s*
                  \n
                )?
              $/
 
 ---
 "Column headers":
 
+  - skip:
+      version: " - 8.11.99"
+      reason:  "node.role column shown by default from 8.12.0 onwards"
+
   - do:
         cat.allocation:
             v: true
@@ -136,7 +155,8 @@
                disk.percent            \s+
                host                    \s+
                ip                      \s+
-               node
+               node                    \s+
+               node.role
                \n
 
               ( \s*                          #allow leading spaces to account for right-justified text
@@ -148,7 +168,8 @@
                 (\d+                  \s+)  #always should return value since we filter out non data nodes by default
                 [-\w.]+                \s+
                 \d+(\.\d+){3}          \s+
-                [-\w.]+
+                [-\w.]+                \s+
+                [\w]+
                 \n
               )+
             $/
@@ -193,6 +214,10 @@
 
 "Bytes":
 
+  - skip:
+      version: " - 8.11.99"
+      reason:  "node.role column shown by default from 8.12.0 onwards"
+
   - do:
       cat.allocation:
         bytes: gb
@@ -208,7 +233,8 @@
                 (\d+                 \s+)  #always should return value since we filter out non data nodes by default
                 [-\w.]+             \s+
                 \d+(\.\d+){3}       \s+
-                [-\w.]+
+                [-\w.]+             \s+
+                [\w]+
                 \n
               )+
             $/

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

@@ -92,7 +92,7 @@ protected Table getTableWithHeader(final RestRequest request) {
         table.addCell("host", "alias:h;desc:host of node");
         table.addCell("ip", "desc:ip of node");
         table.addCell("node", "alias:n;desc:name of node");
-        table.addCell("node.role", "default:false;alias:r,role,nodeRole;desc:node roles");
+        table.addCell("node.role", "alias:r,role,nodeRole;desc:node roles");
         table.endHeaders();
         return table;
     }