Futher flesh out the generator

- Create a per-host directory called overlays/$(overlay)/hostname/$(host.hostname) to have files that
  ought to be included only for that host. Things like /etc/vpp/config/interface.vpp go there
- Rename the "templates" directory as overlays/$(overlay)/common/
- Render one after the other, so a file can exist in common and hostname, the latter taking precedence
- Remove the config for 'pubkeys' and instead just make these common/root/.ssh/* and common/home/ipng/.ssh/*
- Split out bootstrap.vpp so that a per-host include can be overriden for interfaces.vpp
  - But keep a default common/etc/vpp/config/interface.vpp as a placeholder, so that VPP will still start
    even if the per-hostname override isn't provided.
- Generate a fresh output for 'default' on all machines

generate

@@ -72,7 +72,7 @@ def tpl2fn(tpl, prefix):
 
 
 def find(file_or_dir_list):
-    log.info("Finding templates in %s" % file_or_dir_list)
+    log.info("Finding files in %s" % file_or_dir_list)
     ret = {}
     for e in file_or_dir_list:
         if e.startswith("_"):
@@ -91,9 +91,9 @@ def find(file_or_dir_list):
     return ret
 
 
-def generate(templates, data, debug=False):
+def generate(files, data, debug=False):
     output = {}
-    for tpl, fn in templates.items():
+    for tpl, fn in files.items():
         log.info("Rendering %s into %s" % (tpl, fn))
         try:
             output[fn] = render(tpl, data)
@@ -240,18 +240,20 @@ def main():
         log.error("Overlay not defined, bailing.")
         return
 
-    # Assemble a dictionary of tpl=>fn
-    overlay = data["overlays"][args.overlay]
-    template_root = overlay["path"] + "templates/"
-    templates = find([template_root])
 
     for node_id in range(data["lab"]["nodes"]):
         log.info("Generating for node %d" % node_id)
         data["node"] = create_node(data["lab"], node_id)
         log.debug("node: %s" % data["node"])
 
+        # Assemble a dictionary of tpl=>fn
+        overlay = data["overlays"][args.overlay]
+        common_root = overlay["path"] + "common/"
+        hostname_root = overlay["path"] + "hostname/" + data["node"]["hostname"] + "/"
+        files = find([common_root, hostname_root])
+
         # Assemble a dictionary of fn=>output
-        build = generate(templates, data, args.debug)
+        build = generate(files, data, args.debug)
         if not build:
             return