fix(schema): require hostnames of at least 2 characters

CHANGELOG.md

@@ -18,6 +18,7 @@ All notable changes to this project will be documented in this file.
   - **mxGraph**: Updated the vendored mxGraph from 4.1.0 to 4.2.2, the final release before the project was archived. Upstream changed the modifier that deletes a cell together with its connected edges from Shift to Ctrl.
   - **Editor**: The sidebar node palettes now open expanded, the export dialog offers only the XML and SVG formats the server can produce, and the Help button opens the phēnix documentation instead of the defunct `minimega.org`.
 - **Topology validation**: Reject the node hostnames `all`, all-digit names, and `phenix` on Windows nodes, and warn about hostnames that may cause problems.
+- **Topology schema**: Require node hostnames to be at least 2 characters long.
 
 ### Fixed
 

src/go/types/schema_topology_test.go

@@ -90,6 +90,19 @@ func TestTopologySchema(t *testing.T) {
 			node:    withHostname(validNode(), ""),
 			wantErr: true,
 		},
+		{
+			name:    "1-character hostname is rejected",
+			node:    withHostname(validNode(), "a"),
+			wantErr: true,
+		},
+		{
+			name: "2-character hostname is valid",
+			node: withHostname(validNode(), "a1"),
+		},
+		{
+			name: "63-character hostname is valid",
+			node: withHostname(validNode(), strings.Repeat("a", 63)),
+		},
 		{
 			name: "invalid vm_type is rejected",
 			node: func() map[string]any {

src/go/types/version/schemas/v1.yaml

@@ -224,10 +224,21 @@ components:
           - hostname
           properties:
             hostname:
+              # 2 to 63 letters, digits, and interior hyphens. Guest operating
+              # systems phenix configures reject 1-character hostnames.
+              #
+              # VyOS and Vyatta validate `system host-name` against
+              # `[A-Za-z0-9][-.A-Za-z0-9]*[A-Za-z0-9]`, which needs at least 2
+              # characters:
+              # https://docs.vyos.io/en/latest/configuration/system/host-name.html
+              # https://github.com/vyos/vyos-1x/blob/ed218c254d964775ddf24158ac6520972d575faf/interface-definitions/include/constraint/host-name.xml.i
+              #
+              # Windows DNS host names have a 2-character minimum:
+              # https://learn.microsoft.com/en-us/troubleshoot/windows-server/active-directory/naming-conventions-for-computer-domain-site-ou#dns-host-names
               type: string
-              minLength: 1
+              minLength: 2
               maxLength: 63
-              pattern: '^[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?$'
+              pattern: '^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$'
               example: ADServer
             description:
               type: string

src/go/types/version/schemas/v2.yaml

@@ -251,10 +251,21 @@ components:
           - hostname
           properties:
             hostname:
+              # 2 to 63 letters, digits, and interior hyphens. Guest operating
+              # systems phenix configures reject 1-character hostnames.
+              #
+              # VyOS and Vyatta validate `system host-name` against
+              # `[A-Za-z0-9][-.A-Za-z0-9]*[A-Za-z0-9]`, which needs at least 2
+              # characters:
+              # https://docs.vyos.io/en/latest/configuration/system/host-name.html
+              # https://github.com/vyos/vyos-1x/blob/ed218c254d964775ddf24158ac6520972d575faf/interface-definitions/include/constraint/host-name.xml.i
+              #
+              # Windows DNS host names have a 2-character minimum:
+              # https://learn.microsoft.com/en-us/troubleshoot/windows-server/active-directory/naming-conventions-for-computer-domain-site-ou#dns-host-names
               type: string
-              minLength: 1
+              minLength: 2
               maxLength: 63
-              pattern: '^[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?$'
+              pattern: '^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$'
               example: ADServer
             description:
               type: string

src/go/web/public/grapheditor/utils/schemas/container_schema.json

@@ -34,13 +34,13 @@
           "$id": "#/nodes/properties/general/properties/hostname",
           "type": "string",
           "title": "Hostname",
-          "minLength": 1,
+          "minLength": 2,
           "default": "",
           "examples": [
             "power-provider"
           ],
           "maxLength": 63,
-          "pattern": "^[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?$"
+          "pattern": "^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$"
         },
         "description": {
           "$id": "#/nodes/properties/general/properties/description",

src/go/web/public/grapheditor/utils/schemas/kvm_schema.json

@@ -82,12 +82,12 @@
           "$id": "#/nodes/properties/general/properties/hostname",
           "type": "string",
           "title": "Hostname",
-          "minLength": 1,
+          "minLength": 2,
           "examples": [
             "ADServer"
           ],
           "maxLength": 63,
-          "pattern": "^[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?$"
+          "pattern": "^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$"
         },
         "description": {
           "$id": "#/nodes/properties/general/properties/description",

src/go/web/public/grapheditor/utils/schemas/node_schema.json

@@ -73,12 +73,12 @@
           "$id": "#/nodes/properties/general/properties/hostname",
           "type": "string",
           "title": "Hostname",
-          "minLength": 1,
+          "minLength": 2,
           "examples": [
             "ADServer"
           ],
           "maxLength": 63,
-          "pattern": "^[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?$"
+          "pattern": "^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$"
         },
         "description": {
           "$id": "#/nodes/properties/general/properties/description",

src/go/web/public/grapheditor/utils/schemas/schema.json

@@ -102,13 +102,13 @@
                 "$id": "#/properties/nodes/items/properties/general/properties/hostname",
                 "type": "string",
                 "title": "Hostname",
-                "minLength": 1,
+                "minLength": 2,
                 "default": "",
                 "examples": [
                   "power-provider"
                 ],
                 "maxLength": 63,
-                "pattern": "^[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?$"
+                "pattern": "^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$"
               },
               "description": {
                 "$id": "#/properties/nodes/items/properties/general/properties/description",

src/go/web/public/grapheditor/utils/schemas/topo_schema.json

@@ -122,12 +122,12 @@
               "$id": "#/nodes/properties/general/properties/hostname",
               "type": "string",
               "title": "Hostname",
-              "minLength": 1,
+              "minLength": 2,
               "examples": [
                 "ADServer"
               ],
               "maxLength": 63,
-              "pattern": "^[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?$"
+              "pattern": "^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$"
             },
             "description": {
               "$id": "#/nodes/properties/general/properties/description",
@@ -1076,12 +1076,12 @@
               "$id": "#/nodes/properties/general/properties/hostname",
               "type": "string",
               "title": "Hostname",
-              "minLength": 1,
+              "minLength": 2,
               "examples": [
                 "ADServer"
               ],
               "maxLength": 63,
-              "pattern": "^[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?$"
+              "pattern": "^[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9]$"
             },
             "description": {
               "$id": "#/nodes/properties/general/properties/description",