NVUE Snippets

NVUE supports both traditional snippets and flexible snippets:

• Use a traditional snippet to add configuration to the /etc/network/interfaces, /etc/frr/frr.conf, /etc/frr/daemons, /etc/cumulus/switchd.conf, /etc/cumulus/datapath/traffic.conf or /etc/ssh/sshd_config file.
• Use a flexible snippet to manage any other text file on the system.

Traditional Snippets

Use traditional snippets if you configure Cumulus Linux with NVUE commands, then want to configure a feature that does not yet support the NVUE Object Model. You create a snippet in yaml format, then add the configuration to the file with the nv config patch command.

/etc/frr/frr.conf Snippets

Example 1: Top Level Configuration

NVUE does not support configuring BGP to peer across the default route. The following example configures BGP to peer across the default route from the default VRF:

1. Create a .yaml file with the following traditional snippet:

   cumulus@switch:~$ sudo nano bgp_snippet.yaml
   - set:
       system:
         config:
           snippet:
             frr.conf: |
               ip nht resolve-via-default
   

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch bgp_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the configuration exists at the end of the /etc/frr/frr.conf file:

   cumulus@switch:~$ sudo cat /etc/frr/frr.conf
   ...
   ! end of router ospf block
   !---- CUE snippets ----
   ip nht resolve-via-default
   

Example 2: Nested Configuration

NVUE does not support configuring EVPN route targets using auto derived values from RFC 8365. The following example configures BGP to enable RFC 8365 derived router targets:

1. Create a .yaml file with the following traditional snippet:

   cumulus@switch:~$ sudo nano bgp_snippet.yaml
   - set:
       system:
         config:
           snippet:
             frr.conf: |
               router bgp 65517 vrf default
                 address-family l2vpn evpn
                   autort rfc8365-compatible
   

Make sure to use spaces not tabs; the parser expects spaces in yaml format.

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch bgp_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the configuration exists at the end of the /etc/frr/frr.conf file:

   cumulus@switch:~$ sudo cat /etc/frr/frr.conf
   ...
   ! end of router bgp 65517 vrf default
   !---- CUE snippets ----
   router bgp 65517 vrf default
   address-family l2vpn evpn
   autort rfc8365-compatible
   

The traditional snippets for FRR write content to the /etc/frr/frr.conf file. When you apply the configuration and snippet with the nv config apply command, the FRR service goes through and reads in the /etc/frr/frr.conf file.

Example 3: EVPN Multihoming FRR Debugging

NVUE does not support configuring FRR debugging for EVPN multihoming. The following example configures FRR debugging:

1. Create a .yaml file and add the following traditional snippet:

   cumulus@switch:~$ sudo nano mh_debug_snippet.yaml
   - set:
       system:
         config:
           snippet:
             frr.conf: |
               debug bgp evpn mh es
               debug bgp evpn mh route
               debug bgp zebra
               debug zebra evpn mh es
               debug zebra evpn mh mac
               debug zebra evpn mh neigh
               debug zebra evpn mh nh
               debug zebra vxlan
   

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch mh_debug_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the configuration exists in the /etc/frr/frr.conf file:

   cumulus@switch:~$ sudo cat /etc/frr/frr.conf
   ...
   !---- NVUE snippets ----
   debug bgp evpn mh es
   debug bgp evpn mh route
   debug bgp zebra
   debug zebra evpn mh es
   debug zebra evpn mh mac
   debug zebra evpn mh neigh
   debug zebra evpn mh nh
   debug zebra vxlan
   

The traditional snippets for FRR write content to the /etc/frr/frr.conf file. When you apply the configuration and snippet with the nv config apply command, the FRR service goes through and reads in the /etc/frr/frr.conf file.

/etc/network/interfaces Snippets

MLAG Timers Example

NVUE supports configuring only one of the MLAG service timeouts (initDelay). The following example configures the MLAG peer timeout to 400 seconds:

1. Create a .yaml file and add the following traditional snippet:

   cumulus@switch:~$ sudo nano mlag_snippet.yaml
   - set:
       system:
         config:
           snippet:
             ifupdown2_eni:
               peerlink.4094: |
                 clagd-args --peerTimeout 400
   

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch mlag_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the configuration exists in the peerlink.4094 stanza of the /etc/network/interfaces file:

   cumulus@switch:~$ sudo cat /etc/network/interfaces
   ...
   auto peerlink.4094
   iface peerlink.4094
    clagd-args --peerTimeout 400
    clagd-peer-ip linklocal
    clagd-backup-ip 10.10.10.2
    clagd-sys-mac 44:38:39:BE:EF:AA
    clagd-args --initDelay 180
   ...
   

Traditional Bridge Example

NVUE does not support configuring traditional bridges. The following example configures a traditional bridge called br0 with the IP address 11.0.0.10/24. swp1, swp2 are members of the bridge.

1. Create a .yaml file and add the following traditional snippet:

   cumulus@switch:~$ sudo nano bridge_snippet.yaml
   - set:
       system:
        config:
          snippet:
            ifupdown2_eni:
              eni_stanzas: |
                auto br0
                iface br0
                  address 11.0.0.10/24
                  bridge-ports swp1 swp2
                  bridge-vlan-aware no
   

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch bridge_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the configuration exists at the end of the /etc/network/interfaces file:

   cumulus@switch:~$ sudo cat /etc/network/interfaces
   ...
   auto br0
   iface br0
     address 11.0.0.10/24
     bridge-ports swp1 swp2
     bridge-vlan-aware no
   

VLAN-aware RSTP Timers Example

NVUE does not support configuring RSTP timers on VLAN-aware bridges. The following example configures non-default RSTP timers for the NVUE default bridge br_default:

1. Create a .yaml file and add the following traditional snippet:

   cumulus@switch:~$ sudo nano vlan-aware_bridge_snippet.yaml
   - set:
       system:
         config:
           snippet:
             ifupdown2_eni:
               br_default: |
                 mstpctl-maxage 10
                 mstpctl-hello 1
                 mstpctl-fdelay 8
   

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch vlan-aware_bridge_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the configuration exists at the end of the /etc/network/interfaces file:

   cumulus@switch:~$ sudo cat /etc/network/interfaces
   ...
   auto br_default
   iface br_default
       mstpctl-maxage 10
       mstpctl-hello 1
       mstpctl-fdelay 8
   ...
   

/etc/cumulus/datapath/traffic.conf Snippets

To add data path configuration for the Cumulus Linux switchd module that NVUE does not yet support, create a traffic.conf snippet.

The following example creates a file called traffic_conf_snippet.yaml and enables the resilient hash setting.

1. Create a .yaml file and add the following traditional snippet:

   cumulus@switch:~$ sudo nano traffic_conf_snippet.yaml
   - set:
       system:
         config:
           snippet:
             traffic.conf: |
               resilient_hash_enable = TRUE
   

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch traffic_conf_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the configuration exists at the end of the /etc/cumulus/datapath/traffic.conf file:

   cumulus@switch:~$ sudo cat /etc/cumulus/datapath/traffic.conf
   ...
   !---- NVUE snippets ----
   resilient_hash_enable = TRUE
   

/etc/snmp/snmpd.conf Snippets

To add Cumulus Linux SNMP agent configuration not yet available with NVUE commands, create an snmpd.conf snippet.

The following example creates a file called snmpd.conf_snippet.yaml, and sets the read only community string and the listening address to run in the mgmt VRF.

1. Create a .yaml file and add the following traditional snippet:

   cumulus@switch:~$ sudo nano snmpd.conf_snippet.yaml
   - set:
       system:
         config:
           snippet:
             snmpd.conf: |
               rocommunity cumuluspassword default
               agentaddress udp:@mgmt:161
   

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch snmpd.conf_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the configuration exists at the end of the /etc/snmp/snmpd.conf file:

   cumulus@switch:~$ sudo cat /etc/snmp/snmpd.conf
   ...
   !---- NVUE SNMP Server Snippets ----
   rocommunity cumuluspassword default
   agentaddress udp:@mgmt:161
   

/etc/ssh/sshd_config Snippets

To add SSH service configuration not yet available with NVUE commands, create an sshd_config snippet.

The following example creates a file called sshd_config_snippet.yaml to allow root login and enable X11 forwarding for all users except user anoncvs. The snippet also disables TCP forwarding for the anoncvs user and runs the cvs server command when anoncvs logs in.

1. Create a .yaml file and add the following traditional snippet:

   cumulus@switch:~$ sudo nano sshd_config_snippet.yaml
   - set:
       system:
         config:
           snippet:
             sshd_config: |
               PermitRootLogin yes
               X11Forwarding yes
               Match User anoncvs
                  X11Forwarding no
                  AllowTcpForwarding no
                  ForceCommand cvs server
   

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch sshd_config_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the configuration exists at the end of the /etc/ssh/sshd_config file:

   cumulus@switch:~$ sudo cat /etc/ssh/sshd_config
   ...
   !---- NVUE snippets ----
   PermitRootLogin yes
   X11Forwarding yes
   Match User anoncvs
      X11Forwarding no
      AllowTcpForwarding no
      ForceCommand cvs server
   

Flexible Snippets

Flexible snippets are an extension of traditional snippets that let you manage any text file on the system.

• You can create new file or modify an existing file that NVUE does not manage.
• You can add configuration to a file that NVUE manages.

The account you use through the CLI or the REST API to configure and manage flexible snippets must be in the sudo group, which includes the NVUE system-admin role, or you must be the root user.

Files NVUE Manages

You can use flexible snippets to add configuration to the following files that NVUE manages:

Flexible snippets do not support:

• Binary files.
• Symbolic links.
• More than 1MB of content.
• More than one flexible snippet in the same destination file.

Create a Flexible Snippet

To create a flexible snippet:

1. Create a file in yaml format and add each flexible snippet you want to apply in the format shown below. NVUE appends the flexible snippet at the end of an existing file. If the file does not exist, NVUE creates the file, then adds the content.

   cumulus@leaf01:mgmt:~$ sudo nano <filename>.yaml>
   - set:
       system:
        config:
          snippet:
            <snippet-name>:
              file: "<filename>"
              permissions: "<umask-permissions>"
              content: |
                # This is my content
              services:
                 <name>:
                   service: <service-name>
                   action: <action>
   

   • You can only set the umast permissions to a new file that you create. Adding the permissions: line is optional. The default umask persmissions are 644.
   • You can add a service with an action, such as start, restart, or stop. Adding the services: lines is optional; however, if you add the service: line, you must specify at least one service.

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch <filename>.yaml>
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify the patched configuration.

Flexible Snippet Examples

The following example flexible snippet called crontab-flex-snippet appends the single line @daily /opt/utils/run-backup.sh to the existing /etc/crontab file, then restarts the cron service.

cumulus@leaf01:mgmt:~$ sudo nano crontab-flex-snippet.yaml
- set:
    system:
      config:
        snippet:
          crontab-flex-snippet:
            file: "/etc/crontab"
            content: |
              @daily /opt/utils/run-backup.sh
            services:
              schedule:
                service: cron
                action: restart

The following example flexible snippet called apt-flex-snippet creates a new file /etc/apt/sources.list.d/microsoft-prod.list with 0644 permissions and adds multi-line text:

cumulus@leaf01:mgmt:~$ sudo nano apt-flex-snippet.yaml
- set:
    system:
      config:
        snippet:
          apt-flexible-snippet:
            file: "/etc/apt/sources.list.d/microsoft-prod.list"
            content: |
              # Adding Microsoft SQL Server Sources
              deb [arch=amd64] https://packages.microsoft.com/debian/10/prod buster main
            permissions: "0644"

The following flexible snippet called lldp_config_snipppet disables LLDP on swp1 and swp2 using the configure system interface pattern-blacklist command:

cumulus@leaf01:mgmt:~$ sudo nano lldp_config_snipppet.yaml
- set:
    system:
      config:
        snippet:
          lldp-interfaces-config:
            file: "/etc/lldpd.d/lldp-interfaces.conf"
            content: |
              configure system interface pattern-blacklist swp1,swp2
              services:
                lldp:
                  service: lldpd
                  action: restart

The following flexible snippet disables LLDP on swp1 and swp2 using the system interface pattern keyword:

cumulus@leaf01:mgmt:~$ sudo nano lldp_config_snipppet.yaml
- set:
    system:
      config:
        snippet:
          lldp-interfaces-config:
            file: "/etc/lldpd.d/lldp-interfaces.conf"
            content: |
              configure system interface pattern eth*,swp*,!swp1,!swp2
            services:
              lldp:
                service: lldpd
                action: restart

After you patch and apply the configuration above, the snippet creates a new file in the /etc/lldp.d directory, then restarts the lldpd service to stop LLDP transmitting and receiving on swp1 and swp2. Other interfaces continue to participate in LLDP.

cumulus@leaf01:mgmt:~$ nv config apply
Invalid config [rev_id: 8]
  Flexible snippets are not allowed to be configured on the file '/etc/cumulus/ports.conf’.
  Flexible snippets are not allowed to be configured on the file '/etc/cumulus/ports_width.conf’.

cumulus@leaf01:mgmt:~$ nv config apply
Invalid config [rev_id: 1]
  Flexible snippet cannot be used to modify the file '/etc/ssh/sshd_config'. Traditional snippets (for e.g., 'sshd_config') are supported on this file. Consult NVIDIA NVUE documentation for further information on snippets.

You can also create a flexible snippet with the REST API. See NVUE API.

Remove a Snippet

To remove a traditional or flexible snippet, edit the snippet’s .yaml file to change set to unset, then patch and apply the configuration. Alternatively, you can use the REST API DELETE and PATCH methods.

The following example removes the MLAG timer traditional snippet created above to configure the MLAG peer timeout:

1. Edit the mlag_snippet.yaml file to change set to unset:

   cumulus@switch:~$ sudo nano mlag_snippet.yaml
   - unset:
       system:
         config:
           snippet:
             ifupdown2_eni:
   

2. Run the following command to patch the configuration:

   cumulus@switch:~$ nv config patch mlag_snippet.yaml
   

3. Run the nv config apply command to apply the configuration:

   cumulus@switch:~$ nv config apply
   

4. Verify that the peer timeout parameter no longer exists in the peerlink.4094 stanza of the /etc/network/interfaces file:

   cumulus@switch:~$ sudo cat /etc/network/interfaces
   ...
   auto peerlink.4094
   iface peerlink.4094
    clagd-peer-ip linklocal
    clagd-backup-ip 10.10.10.2
    clagd-sys-mac 44:38:39:BE:EF:AA
    clagd-args --initDelay 180
   ...