Expand `/_cat/nodes` to return information about hard drive (#21775)

Expand `/_cat/nodes` with already present information about available disk space `diskAvail` (alias: `d`, `disk`) by:

    * `diskTotal` (alias `dt`): total disk space
    * `diskUsed` (alias `du`): used disk space (`diskTotal - diskAvail`)
    * `diskUsedPercent` (alias `dup`): used disk space percentage

Note: The available disk space is the number of bytes available to the node's Java virtual machine. The size might be smaller than the real one. That means the used disk space (percentage) is larger.

Closes #21679

1 files changed, 32 insertions, 0 deletions

diff --git a/rest-api-spec/src/main/resources/rest-api-spec/test/cat.nodes/10_basic.yml b/rest-api-spec/src/main/resources/rest-api-spec/test/cat.nodes/10_basic.yml
index f48f73cb47..e1225ef5da 100755
--- a/rest-api-spec/src/main/resources/rest-api-spec/test/cat.nodes/10_basic.yml
+++ b/rest-api-spec/src/main/resources/rest-api-spec/test/cat.nodes/10_basic.yml
@@ -59,6 +59,38 @@
                /^      http \n ((\d{1,3}\.){3}\d{1,3}:\d{1,5}\n)+  $/
 
 ---
+"Additional disk information":
+  - skip:
+      version: " - 5.5.99"
+      reason:  additional disk info added in 5.6.0
+
+  - do:
+      cat.nodes:
+          h: diskAvail,diskTotal,diskUsed,diskUsedPercent
+          v: true
+
+  - match:
+      # leading whitespace on columns and optional whitespace on values is necessary
+      # because `diskAvail` is right aligned and text representation of disk size might be
+      # longer so it's padded with leading whitespace
+      $body: |
+               /^  \s* diskAvail            \s+ diskTotal            \s+ diskUsed            \s+ diskUsedPercent            \n
+                  (\s* \d+(\.\d+)?[ptgmk]?b \s+ \d+(\.\d+)?[ptgmk]?b \s+ \d+(\.\d+)?[ptgmk]?b\s+ (100\.00 | \d{1,2}\.\d{2}) \n)+  $/
+
+  - do:
+      cat.nodes:
+          h: disk,dt,du,dup
+          v: true
+
+  - match:
+      # leading whitespace on columns and optional whitespace on values is necessary
+      # because `disk` is right aligned and text representation of disk size might be
+      # longer so it's padded with leading whitespace
+      $body: |
+               /^  \s* disk                 \s+ dt                   \s+ du                  \s+ dup                        \n
+                  (\s* \d+(\.\d+)?[ptgmk]?b \s+ \d+(\.\d+)?[ptgmk]?b \s+ \d+(\.\d+)?[ptgmk]?b\s+ (100\.00 | \d{1,2}\.\d{2}) \n)+  $/
+
+---
 "Test cat nodes output with full_id set":
   - skip:
       version: " - 5.0.0"