scripts: T4269: node.def generator should automatically add default values

Since introducing the XML <defaultValue> node it was common, but redundant,
practice to also add a help string indicating which value would be used as
default if the node is unset.

This makes no sense b/c it's duplicated code/value/characters and prone to
error. The node.def scripts should be extended to automatically render the
appropriate default value into the CLI help string.

For e.g. SSH the current PoC renders:

$ cat templates-cfg/service/ssh/port/node.def
  multi:
  type: txt
  help: Port for SSH service (default: 22)
  val_help: u32:1-65535; Numeric IP port
  ...

Not all subsystems are already migrated to get_config_dict() and make use of
the defaults() call - those subsystems need to be migrated, first before the new
default is added to the CLI help.

1 files changed, 1 insertions, 0 deletions

diff --git a/interface-definitions/dns-domain-name.xml.in b/interface-definitions/dns-domain-name.xml.in
index 005a55ab3..7ae537d00 100644
--- a/interface-definitions/dns-domain-name.xml.in
+++ b/interface-definitions/dns-domain-name.xml.in
@@ -29,6 +29,7 @@
           </constraint>
         </properties>
       </leafNode>
+      <!-- script does not use XML defaults so far -->
       <leafNode name="host-name" owner="${vyos_conf_scripts_dir}/host_name.py">
         <properties>
           <help>System host name (default: vyos)</help>