Configure network-mode for clab nodes (ipspace#2735)

* Standard way configure network-mode for clab nodes
* Skip provisioning eth0 when clab.network-mode=='none'
* Explain why we'd need 'network-mode: none' and add integration test

Author: jbemmel

docs/labs/clab.md

@@ -145,6 +145,8 @@ In multi-provider topologies, set the **uplink** parameter only for the primary
 
 You can change a device management interface's IPv4/IPv6 address with the **mgmt.ipv4**/**mgmt.ipv6** node parameter *as long as the specified IPv4/IPv6 address is within the subnet specified in the **addressing.mgmt** pool*. However, it is recommended to use the **addressing.mgmt** pool **ipv4**/**ipv6**/**start** parameters to adjust the address range used for management IP addresses and rely on *netlab* to assign management IP addresses to containers based on [device node ID](node-augment).
 
+You can also set the **clab.network-mode** node parameter to *none* to disconnect a container from the management network. Use this setting in very large topologies (more than 1000 devices) to disconnect devices that don't run an SSH server from the management Linux bridge as a workaround for the *no more than 1024 interfaces per Linux bridge* limitation of the Linux kernel.
+
 (clab-port-forwarding)=
 ### Port Forwarding
 
@@ -364,6 +366,7 @@ You can also change these *containerlab* parameters:
 * **clab.cmd** to [change the command of a container image](https://containerlab.dev/manual/nodes/#cmd).
 * **clab.startup-delay** to make certain node(s) [boot/start later than others](https://containerlab.dev/manual/nodes/#startup-delay) (amount in seconds)
 * **clab.restart-policy** to set the [container restart policy](https://containerlab.dev/manual/nodes/#restart-policy)
+* **clab.network-mode** to set the [network-mode](https://containerlab.dev/manual/nodes/#network-mode)
 
 ```{warning}
 String values (for example, the command to execute specified in **clab.cmd**) are put into single quotes when written into the `clab.yml` containerlab configuration file. Ensure you're not using single quotes in your command line.

netsim/ansible/templates/initial/frr.j2

@@ -50,7 +50,7 @@ else
   apt-get update -qq && apt-get install -qq frr frr-pythontools bridge-utils ethtool
 fi
 {% else %}
-{%   if netlab_mgmt_vrf|default(False) %}
+{%   if netlab_mgmt_vrf|default(False) and clab['network-mode']|default('')!='none' %}
 #
 # Get the current next hop for the default route
 #

netsim/providers/clab.yml

@@ -46,6 +46,7 @@ attributes:
       runtime: str
       startup-delay: int
       restart-policy: str
+      network-mode: str
   interface:
     name: str
   link:

netsim/templates/provider/clab/clab.j2

@@ -17,11 +17,16 @@ topology:
 {% for name,n in nodes.items() if not (n.unmanaged|default(False)) %}
 {%   set clab = n.clab|default({}) %}
     {{ name }}:
-{%   if n.mgmt.ipv4 is defined %}
-      mgmt-ipv4: {{ n.mgmt.ipv4 }}
+{%   if 'network-mode' in clab %}
+      network-mode: {{ clab['network-mode'] }}
 {%   endif %}
-{%   if n.mgmt.ipv6 is defined %}
+{%   if 'network-mode' not in clab or clab['network-mode'] != 'none' %}
+{%     if n.mgmt.ipv4 is defined %}
+      mgmt-ipv4: {{ n.mgmt.ipv4 }}
+{%     endif %}
+{%     if n.mgmt.ipv6 is defined %}
       mgmt-ipv6: {{ n.mgmt.ipv6 }}
+{%     endif %}
 {%   endif %}
 {%   set kind = clab.kind | default(n.device) %}
       kind: {{ kind }}

tests/platform-integration/clab/02-mac-ip.yml

@@ -1,11 +1,15 @@
 message: |
   Tests containers with custom management IP addresses and checks that netlab
-  can successfully configure them.
+  can successfully configure them. It also checks the configuration of containers
+  disconnected from the management network.
 
 provider: clab
 defaults.device: eos
 module: [ ospf ]
-ospf.timers.hello: 1
+ospf.timers:
+  hello: 1
+  dead: 4
+
 defaults.multilab.change.addressing.mgmt.ipv4: '192.42.42.0/24'
 addressing.mgmt.ipv4: '192.42.42.0/24'
 
@@ -18,11 +22,14 @@ nodes:
     mgmt:
       mac: 0A:4F:A9:02:00:01
       ipv4: 192.42.42.207
+  r3:
+    device: frr
+    clab.network-mode: none
 
-links: [ r1-r2 ]
+links: [ r1-r2, r2-r3 ]
 
 validate:
   adj:
     plugin: ospf_neighbor(nodes.r2.ospf.router_id)
     wait: 15
-    nodes: [ r1 ]
+    nodes: [ r1, r3 ]