always quote hcl map keys

HCL identifiers may need to be quoted, so always quote them to be safe.

command/hcl_printer.go

@@ -94,7 +94,7 @@ func (e *encodeState) encodeMap(m map[string]interface{}) error {
 	for i, k := range sortedKeys(m) {
 		v := m[k]
 
-		e.WriteString(k + " = ")
+		e.WriteString(fmt.Sprintf("%q = ", k))
 		err := e.encode(v)
 		if err != nil {
 			return err

command/hcl_printer_test.go

@@ -0,0 +1,52 @@
+package command
+
+import "testing"
+
+// The command package has it's own HCL encoder to encode variables to push.
+// Make sure the variable we encode parse correctly
+func TestHCLEncoder_parse(t *testing.T) {
+	cases := []struct {
+		Name  string
+		Val   interface{}
+		Error bool
+	}{
+		{
+			Name: "int",
+			Val:  12345,
+		},
+		{
+			Name: "float",
+			Val:  1.2345,
+		},
+		{
+			Name: "string",
+			Val:  "terraform",
+		},
+		{
+			Name: "list",
+			Val:  []interface{}{"a", "b", "c"},
+		},
+		{
+			Name: "map",
+			Val: map[string]interface{}{
+				"a": 1,
+			},
+		},
+		// a numeric looking identifier requires quotes
+		{
+			Name: "map_with_quoted_key",
+			Val: map[string]interface{}{
+				"0.0.0.0/24": "mask",
+			},
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.Name, func(t *testing.T) {
+			_, err := encodeHCL(c.Val)
+			if err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+}