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Arista cEOS#

Arista cEOS is identified with ceos kind in the topology file. The ceos kind defines a supported feature set and a startup procedure of a ceos node.

cEOS nodes launched with containerlab comes up with

  • their management interface eth0 configured with IPv4/6 addresses as assigned by docker
  • hostname assigned to the node name
  • gNMI, Netconf and eAPI services enabled
  • admin user created with password admin

Managing ceos nodes#

Arista cEOS node launched with containerlab can be managed via the following interfaces:

to connect to a bash shell of a running ceos container:

docker exec -it <container-name/id> bash

to connect to the ceos CLI

docker exec -it <container-name/id> Cli

NETCONF server is running over port 830

ssh [email protected]<container-name> -p 830 -s netconf

gNMI server is running over port 6030 in non-secure mode using the best in class gnmic gNMI client as an example:

gnmic -a <container-name/node-mgmt-address>:6030 --insecure \
-u admin -p admin \


Default user credentials: admin:admin

Interfaces mapping#

ceos container uses the following mapping for its linux interfaces:

  • eth0 - management interface connected to the containerlab management network
  • eth1 - first data interface

When containerlab launches ceos node, it will set IPv4/6 addresses as assigned by docker to the eth0 interface and ceos node will boot with that addresses configured. Data interfaces eth1+ need to be configured with IP addressing manually.

ceos interfaces output

This output demonstrates the IP addressing of the linux interfaces of ceos node.

bash-4.2# ip address
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet scope host lo
    valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
    valid_lft forever preferred_lft forever
5877: [email protected]: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
    link/ether 02:42:ac:14:14:02 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet brd scope global eth0
    valid_lft forever preferred_lft forever
    inet6 2001:172:20:20::2/80 scope global
    valid_lft forever preferred_lft forever
    inet6 fe80::42:acff:fe14:1402/64 scope link
    valid_lft forever preferred_lft forever
This output shows how the linux interfaces are mapped into the ceos OS.
ceos>sh ip int br
Interface         IP Address           Status       Protocol           MTU    Owner
----------------- -------------------- ------------ -------------- ---------- -------
Management0       up           up                1500

ceos>sh ipv6 int br
Interface       Status        MTU       IPv6 Address                     Addr State    Addr Source
--------------- ------------ ---------- -------------------------------- ---------------- -----------
Ma0             up           1500       fe80::42:acff:fe14:1402/64       up            link local
                                        2001:172:20:20::2/80             up            config
As you see, the management interface Ma0 inherits the IP address that docker assigned to ceos container management interface.

User-defined interface mapping#


Supported in cEOS >= 4.28.0F

It is possible to make ceos nodes boot up with a user-defined interface layout. With the binds property, a user sets the path to the interface mapping file that will be mounted to a container and used during bootup. The underlying linux eth interfaces (used in the containerlab topology file) are mapped to cEOS interfaces in this file. The following shows an example of how this mapping file is structured:

  "ManagementIntf": {
    "eth0": "Management1"
  "EthernetIntf": {
    "eth1": "Ethernet1/1",
    "eth2": "Ethernet2/1",
    "eth3": "Ethernet27/1",
    "eth4": "Ethernet28/1",
    "eth5": "Ethernet3/1/1",
    "eth6": "Ethernet5/2/1"
Linux's eth0 interface is always used to map the management interface.

With the following topology file, containerlab is instructed to take a mymapping.json file located in the same directory as the topology and mount that to the container as /mnt/flash/EosIntfMapping.json. This will result in this interface mapping being considered during the bootup of the node. The destination for that bind has to be /mnt/flash/EosIntfMapping.json.

  1. Craft a valid interface mapping file.
  2. Use binds config option for a ceos node/kind to make this file available in the container's filesystem:

    name: ceos
          kind: ceos
          image: ceos:4.28.0F
            - mymapping.json:/mnt/flash/EosIntfMapping.json:ro # (1)!
          kind: ceos
          image: ceos:4.28.0F
            - mymapping.json:/mnt/flash/EosIntfMapping.json:ro
        - endpoints: ["ceos1:eth1", "ceos2:eth1"]

    1. If all ceos nodes use the same interface mapping file, it is easier to set the bind instruction on a kind level
                  - mymapping.json:/mnt/flash/EosIntfMapping.json:ro
                kind: ceos
                image: ceos:4.28.0F
                kind: ceos
                image: ceos:4.28.0F
      This way the bind is set only once, and nodes of ceos kind will have these binds applied.

Additional interface naming considerations#

While many users will be fine with the default ceos naming of eth, some ceos users may find that they need to name their interfaces et. Interfaces named et provide consistency with the underlying interface mappings within ceos. This enables the correct operation of commands/features which depend on et format interface naming.

In order to align interfaces in this manner, the INTFTYPE environment variable must be set to et in the topology definition file and the links which are defined must be named et, as opposed to eth. This naming requirement does not apply to the eth0 interface automatically created by containerlab. This is only required for links that are used for interconnection with other elements in a topology.


      INTFTYPE: et
  { ... snipped misc. node definition for brevity ... }
    - endpoints: ["ceos_rtr1:et1", "ceos_rtr2:et1"]
    - endpoints: ["ceos_rtr1:et2", "ceos_rtr3:et1"]

Features and options#

Node configuration#

cEOS nodes have a dedicated config directory that is used to persist the configuration of the node. It is possible to launch nodes of ceos kind with a basic config or to provide a custom config file that will be used as a startup config instead.

Default node configuration#

When a node is defined without startup-config statement present, containerlab will generate an empty config from this template and copy it to the config directory of the node.

# example of a topo file that does not define a custom config
# as a result, the config will be generated from a template
# and used by this node
name: ceos
      kind: ceos

The generated config will be saved by the path clab-<lab_name>/<node-name>/flash/startup-config. Using the example topology presented above, the exact path to the config will be clab-ceos/ceos/flash/startup-config.

cEOS Ma0 interface will be configured with a random MAC address with 00:1c:73 OUI part. Containerlab will also create a system_mac_address file in the node's lab directory with the value of a System MAC address. The System MAC address value is calculated as Ma0-MAC-addr + 1.

User defined config#

It is possible to make ceos nodes to boot up with a user-defined config instead of a built-in one. With a startup-config property a user sets the path to the config file that will be mounted to a container and used as a startup config:

name: ceos_lab
      kind: ceos
      startup-config: myconfig.conf

When a config file is passed via startup-config parameter it will be used during an initial lab deployment. However, a config file that might be in the lab directory of a node takes precedence over the startup-config3.

With such topology file containerlab is instructed to take a file myconfig.conf from the current working directory, copy it to the lab directory for that specific node under the /flash/startup-config name and mount that dir to the container. This will result in this config to act as a startup config for the node.

It is possible to change the default config which every ceos node will start with with the following steps:

  1. Craft a valid startup configuration file2.
  2. Use this file as a startup-config for ceos kind:

    name: ceos
        startup-config: ceos-custom-startup.cfg
        # ceos1 will boot with ceos-custom-startup.cfg as set in the kind parameters
          kind: ceos
          image: ceos:4.25.0F
        # ceos2 will boot with its own specific startup config, as it overrides the kind variables
          kind: ceos
          image: ceos:4.25.0F
          startup-config: node-specific-startup.cfg
        - endpoints: ["ceos1:eth1", "ceos2:eth1"]

Saving configuration#

In addition to cli commands such as write memory user can take advantage of the containerlab save command. It saves running cEOS configuration into a startup config file effectively calling the write CLI command.

Container configuration#

To start an Arista cEOS node containerlab uses the configuration instructions described in Arista Forums1. The exact parameters are outlined below.

/sbin/init systemd.setenv=INTFTYPE=eth systemd.setenv=ETBA=1 systemd.setenv=SKIP_ZEROTOUCH_BARRIER_IN_SYSDBINIT=1 systemd.setenv=CEOS=1 systemd.setenv=EOS_PLATFORM=ceoslab systemd.setenv=container=docker systemd.setenv=MAPETH0=1 systemd.setenv=MGMT_INTF=eth0


File mounts#

When a user starts a lab, containerlab creates a node directory for storing configuration artifacts. For ceos kind containerlab creates flash directory for each ceos node and mounts these folders by /mnt/flash paths.

❯ tree clab-srlceos01/ceos
└── flash
    ├── AsuFastPktTransmit.log
    ├── debug
    │   └── proc
    │       └── modules
    ├── fastpkttx.backup
    ├── Fossil
    ├── kickstart-config
    ├── persist
    │   ├── local
    │   ├── messages
    │   ├── persistentRestartLog
    │   ├── secure
    │   └── sys
    ├── schedule
    │   └── tech-support
    │       └── ceos_tech-support_2021-01-14.0907.log.gz
    ├── SsuRestoreLegacy.log
    ├── SsuRestore.log
    ├── system_mac_address
    └── startup-config

9 directories, 11 files

Copy to flash#

If there is a need to copy ceos-specific configuration or override files to the ceos node in the topology use .extras.ceos-copy-to-flash config option. These files will be copied to the node's flash directory and evaluated on startup.

name: ceos
      kind: ceos
        - ceos-config # (1)!
        - toggle_override
  1. Paths are relative to the topology file. Absolute paths like ~/some/path or /some/path are also possible.

Lab examples#

The following labs feature a cEOS node:

Known issues or limitations#

cgroups v1#

In versions prior to EOS-4.28.0F, the ceos-lab image requires a cgroups v1 environment. For many users, this should not require any changes to the runtime environment. However, some Linux distributions (ref: #467) may be configured to use cgroups v2 out-of-the-box4, which will prevent ceos-lab image from booting. In such cases, the users will need to configure their system to utilize a cgroups v1 environment.

Consult your distribution's documentation for details regarding configuring cgroups v1 in case you see similar startup issues as indicated in #467.

Starting with EOS-4.28.0F, ceos-lab will automatically determine whether the container host is using cgroups v1 or cgroups v2 and act appropriately. No configuration is required.

Switching to cgroup v1 in Ubuntu 21.04

To switch back to cgroup v1 in Ubuntu 21+ users need to add a kernel parameter systemd.unified_cgroup_hierarchy=0 to GRUB config. Below is a snippet of /etc/default/grub file with the added systemd.unified_cgroup_hierarchy=0 parameter.

Note that sudo update-grub is needed once changes are made to the file.

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="transparent_hugepage=never quiet splash systemd.unified_cgroup_hierarchy=0"


When running under WSL2 ceos datapath might appear not working. As of Feb 2022 users would need to manually enter the following iptables rules inside ceos container:

sudo iptables -P INPUT ACCEPT
sudo ip6tables -P INPUT ACCEPT


  2. feel free to omit the IP addressing for Management interface, as it will be configured by containerlab when ceos node boots. 

  3. if startup config needs to be enforced, either deploy a lab with --reconfigure flag, or use enforce-startup-config setting. 

  4. for example, Ubuntu 21.04 comes with cgroup v2 by default

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