Display netlab defaults as (exported) environment variables

docs/netlab/defaults.md

@@ -19,26 +19,29 @@
 ```text
 usage: netlab defaults [-h] [-r] [--delete] [-s] [--directory] [--project] [--user]
                        [--system] [--package] [--yes] [--yaml]
+                       [--format {yaml,env,export}]
                        [setting]
 
 Manage netlab default settings
 
 positional arguments:
-  setting       Specify setting to set (with s=v) or display (can be a glob)
+  setting               Specify setting to set (with s=v) or display (can be a glob)
 
 options:
-  -h, --help    show this help message and exit
-  -r, --regex   Display default settings matching a regular expression
-  --delete      Delete the settings matching the specified pattern from the specified
-                datastore
-  -s, --source  Display the source of the default setting
-  --directory   Display or store settings from the current directory
-  --project     Display or store settings from the current project defaults
-  --user        Display or store settings from the user default file
-  --system      Display or store settings from the system default file
-  --package     Display settings included in netlab package
-  --yes         Overwrite existing settings without a confirmation
-  --yaml        Store changed defaults in expanded YAML format
+  -h, --help            show this help message and exit
+  -r, --regex           Display default settings matching a regular expression
+  --delete              Delete the settings matching the specified pattern from the
+                        specified datastore
+  -s, --source          Display the source of the default setting
+  --directory           Display or store settings from the current directory
+  --project             Display or store settings from the current project defaults
+  --user                Display or store settings from the user default file
+  --system              Display or store settings from the system default file
+  --package             Display settings included in netlab package
+  --yes                 Overwrite existing settings without a confirmation
+  --yaml                Store changed defaults in expanded YAML format
+  --format {yaml,env,export}
+                        Alternate output format of the "show" action
 ```
 
 ```{note}
@@ -69,13 +72,24 @@ devices.csr.clab.image = vrnetlab/vr-csr:17.03.04 (netlab)
 devices.csr.clab.image = vrnetlab/cisco_csr1000v:17.03.08 (user)
 ```
 
+You can also display the default settings as environment variables (that you can change for subsequent **netlab up** commands) or as exported environment variables:
+
+```bash
+$ netlab defaults --format env devices.srlinux.clab.image
+NETLAB_DEVICES_SRLINUX_CLAB_IMAGE=ghcr.io/nokia/srlinux:26.3.2
+$ netlab defaults --format export devices.srlinux.clab.image
+export NETLAB_DEVICES_SRLINUX_CLAB_IMAGE=ghcr.io/nokia/srlinux:26.3.2
+```
+
 Specify a default prefix to display a subset of defaults. For example, to display Arista EOS EVPN features, use **devices.eos.features.evpn** parameter:
 
 ```
 $ netlab defaults devices.eos.features.evpn
 devices.eos.features.evpn.asymmetrical_irb = True
-devices.eos.features.evpn.bundle = ['vlan_aware']
+devices.eos.features.evpn.bundle = [vlan_aware]
+devices.eos.features.evpn.ipv6 = True
 devices.eos.features.evpn.irb = True
+devices.eos.features.evpn.transport = [vxlan, mpls, sr]
 ```
 
 You can also use glob expressions to select the parameters you want to display. For example, use `*clab.image*` to display all containerlab image settings:

netsim/cli/defaults.py

@@ -5,6 +5,7 @@
 import fnmatch
 import pathlib
 import re
+import shlex
 import typing
 
 import yaml
@@ -71,6 +72,12 @@ def defaults_parse(args: typing.List[str]) -> argparse.Namespace:
     dest='yaml',
     action='store_true',
     help='Store changed defaults in expanded YAML format')
+  parser.add_argument(
+    '--format',
+    dest='format',
+    action='store',
+    choices=['yaml','env','export'],
+    help='Alternate output format of the "show" action')
   parser.add_argument(
     dest='setting',
     action='store',
@@ -221,18 +228,31 @@ def get_re_pattern(txt: str, regex: bool = False) -> re.Pattern:
 
   return reobj
 
-def print_def_list(def_expanded: Box, show_source: bool) -> None:
+def print_def_list(def_expanded: Box, args: argparse.Namespace) -> None:
+  def_dict = def_expanded.to_dict()
+  to_yaml = args.format == 'yaml'
   for k in sorted(def_expanded):
     ns_list = list(def_expanded[k])
-    if show_source:
+    if args.source and not args.format:
       for ns in ns_list:
         txt = f'{k} = {def_expanded[k][ns]} ({ns})'
         if ns != ns_list[-1] and strings.rich_color:
           strings.rich_console.print(f'[dim]{txt}[/dim]')
         else:
           print(txt)
     else:
-      print(f'{k} = {def_expanded[k][ns_list[-1]]}')
+      v = def_dict[k][ns_list[-1]]
+      is_obj = isinstance(v,(dict,list))
+      v_txt = yaml.dump(v,default_flow_style=True,width=9999).split("\n")[0] if is_obj or to_yaml else str(v)
+      if not args.format:
+        print(f'{k} = {v_txt}')
+      elif args.format == 'yaml':
+        print(f'{k}: {v_txt}')
+      else:
+        key = 'NETLAB_'+k.replace('_','__').replace('.','_').upper()
+        if args.format == 'export':
+          key = 'export '+key
+        print(f'{key}={shlex.quote(v_txt)}')
 
 def default_show(args: argparse.Namespace) -> None:
   global D_SOURCES
@@ -242,7 +262,7 @@ def default_show(args: argparse.Namespace) -> None:
   def_expanded = build_defaults_sources(reobj,d_sources)
 
   if def_expanded:
-    print_def_list(def_expanded,args.source)
+    print_def_list(def_expanded,args)
   else:
     d_src_txt = '' if d_sources == D_SOURCES else f' in {",".join(d_sources)} defaults'
     error_and_exit(f'{args.setting}{" regular expression" if args.regex else ""} not found{d_src_txt}',module='-')