core: disallow brackets in VM names [GH-4319]

CHANGELOG.md

@@ -36,6 +36,8 @@ BUG FIXES:
   - core: Cleanup all temp files. [GH-4103]
   - core: User curlrc is not loaded, preventing strange download issues.
       [GH-4328]
+  - core: VM names may no longer contain brackets, since they cause
+      issues with some providers. [GH-4319]
   - commands/package: base package won't crash with exception [GH-4017]
   - commands/rsync-auto: Destroyed machines won't raise exceptions. [GH-4031]
   - communicators/ssh: Nicer error if remote unexpectedly disconects. [GH-4038]

plugins/kernel_v2/config/vm.rb

@@ -660,6 +660,15 @@ module VagrantPlugins
           end
         end
 
+        # Validate sub-VMs if there are any
+        @__defined_vms.each do |name, _|
+          if name =~ /[\[\]\{\}]/
+            errors["vm"] << I18n.t(
+              "vagrant.config.vm.name_invalid",
+              name: name)
+          end
+        end
+
         errors
       end
     end

templates/locales/en.yml

@@ -1250,6 +1250,8 @@ en:
         hostname_invalid_characters: |-
           The hostname set for the VM should only contain letters, numbers,
           hyphens or dots. It cannot start with a hyphen or dot.
+        name_invalid: |-
+          The sub-VM name '%{name}' is invalid. Please don't use special characters.
         network_ip_ends_in_one: |-
           You assigned a static IP ending in ".1" to this machine.
           This is very often used by the router and can cause the

test/unit/plugins/kernel_v2/config/vm_test.rb

@@ -121,6 +121,27 @@ describe VagrantPlugins::Kernel_V2::VMConfig do
     end
   end
 
+  describe "#define" do
+    it "should allow regular names" do
+      subject.define "foo"
+      subject.finalize!
+
+      assert_valid
+    end
+
+    [
+      "foo [1]",
+      "bar {2}",
+    ].each do |name|
+      it "should disallow names with brackets" do
+        subject.define name
+        subject.finalize!
+
+        assert_invalid
+      end
+    end
+  end
+
   describe "#guest" do
     it "is nil by default" do
       subject.finalize!