docker-topo

Docker network topology builder

Supported images

• Arista cEOS-lab
• Arista vEOS-lab
• Arista CVP
• All vrnetlab images - experimental support, currently only tested with CSR1k, vMX and XRv.
• User-defined docker images

Installation

With Python virtualenv (recommended)

python3 -m pip install virtualenv
python3 -m virtualenv testdir; cd testdir
source bin/activate 
pip install git+https://github.com/networkop/docker-topo.git

Without virtualenv

python3 -m pip install git+https://github.com/networkop/docker-topo.git

Note: Python 2.x is not supported

Usage

# docker-topo -h
usage: docker-topo [-h] [-d] [--create | --destroy] [-s] [-a] topology

Tool to create cEOS topologies

positional arguments:
  topology       Topology file

optional arguments:
  -h, --help     show this help message and exit
  -d, --debug    Enable Debug

Actions:
  Create or destroy topology

  --create       Create topology
  --destroy      Destroy topology

Save:
  Save or archive the topology

  -s, --save     Save topology configs
  -a, --archive  Archive topology file and configs

Topology file

Topology file is a YAML file describing how docker containers are to be interconnected. This information is stored in the links variable which contains a list of links. Each link is described by a unique set of connected interfaces. There are several versions of topology file formats.

Topology file v1

This version is considered legacy and is documented here.

Topology file v2

Each link in a links array is a dictionary with the following format:

VERSION: 2
links:
  - endpoints:
      - "Device-A:Interface-2" 
      - "Device-B:Interface-1"
  - driver: macvlan
    driver_opts: 
      parent: wlp58s0
    endpoints: ["Device-A:Interface-1", "Device-B:Interface-2"]

Each link dictionary supports the following elements:

• endpoints - the only mandatory element, contains a list of endpoints to be connected to a link.
• driver - defines the link driver to be used. Currently supported drivers are veth, bridge, macvlan. When driver is not specified, default bridge driver is used. The following limitations apply:
  • macvlan driver will require a mandatory driver_opts object described below
  • veth driver is talking directly to netlink (no libnetwork involved) and making changes to namespaces
• driver_opts - optional object containing driver options as required by Docker's libnetwork. Currently only used for macvlan's parent interface definition

Each link endpoint is encoded as "DeviceName:InterfaceName:IPPrefix" with the following contraints:

• DeviceName determines which docker image is going to be used by (case-insensitive) matching of the following strings:
  • host - alpine-host image is going to be used
  • cvp - cvp image is going to be used
  • veos - Arista vEOS image built according to the procedure described here
  • vmx - Juniper vMX image built with vrnetlab
  • csr - Cisco CSR1000v image built with vrnetlab
  • xrv - Cisco IOS XRv image built with vrnetlab
  • For anything else Arista cEOS image will be used
• InterfaceName must match the exact name of the interface you expect to see inside a container. For example if you expect to connect a link to DeviceA interface eth0, endpoint definition should be "DeviceA:eth0"
• IPPrefix - Optional parameter that works ONLY for alpine-host devices and will attempt to configure a provided IP prefix inside a container.

Bridge vs veth driver caveats

Both bridge and veth driver have their own set of caveats. Keep them in mind when choosing a driver:

Features	bridge	veth
multipoint links	supported	not supported
sudo privileges	not required	required
docker modifications	requires patched docker deamon	uses standard docker daemon
L2 multicast	only LLDP	supported

You can mix both bridge and veth drivers in the same topology, however make sure that bridge driver links always come first, followed by the veth links. For example:

VERSION: 2
driver: veth

links:
  - endpoints: ["Leaf1:eth1", "Leaf2:eth1"]
    driver: 'bridge'
  - endpoints: ["Leaf1:eth2", "Leaf2:eth2"]
  - endpoints: ["Leaf1:eth3", "Leaf2:eth3"]

(Optional) Global variables

Along with the mandatory link array, there are a number of options that can be specified to override some of the default settings. Below are the list of options with their default values:

VERSION: 1  # Topology file version. Accepts [1|2]
CEOS_IMAGE: ceos:latest # cEOS docker image name
CONF_DIR: './config' # Config directory to store cEOS startup configuration files
PUBLISH_BASE: 8000 # Publish cEOS ports starting from this number
OOB_PREFIX: '192.168.100.0/24' # Only used when link contains CVP. This prefix is assinged to CVP's eth1
PREFIX: 'CEOS-LAB' # This will default to a topology filename (without .yml extension)
driver: None

All of the capitalised global variables can also be provided as environment variables with the following priority:

1. Global variables defined in a topology file
2. Global variables from environment variables
3. Defaults

The final driver variable can be used to specify the default link driver for ALL links at once. This can be used to create all links with non-default veth type drivers:

VERSION: 2
driver: veth
links:
  - endpoints: ["host1:eth1", "host2:eth1"]
  - endpoints: ["host1:eth2", "host3:eth1"]

There should be several examples in the ./topo-extra-files/examples directory

(Optional) Exposing arbitrary ports

By default, PUBLISH_BASE will expose internal HTTPS (443/tcp) port of a container. It is possible to expose any number of internal ports for each container by defining PUBLISH_BASE in the following way:

PUBLISH_BASE:
  443/tcp: None # Will expose inside 443 to a random outside port
  22/tcp: 2000 # All containers will get their ports exposed starting from outside port 2000
  161/tcp: [127.0.0.1, 1600] # Similar to the above but only exposes ports on the defined local IP address

Note: topology file must have at least one interface of type bridge in order for PUBLISH_BASE to work.

(Optional) Saving and archiving network topologies

By default, docker-topo will pick up any files located in the CONF_DIR and, if the filename matches the PREFIX_DEVICENAME, will mount it inside the container as /mnt/flash/startup-config.

When the topology is running, there's a way to easily save the output of "show run" from each device inside the CONF_DIR to make them available on next reboot:

$ docker-topo -s topology.yml
Config directory exists, existing files may be overwritten. Continue? [y/n]:y
INFO:__main__:All configs saved in ./config

Archive option creates a tar.gz file with the CONF_DIR directory and the topology YAML file

$ docker-topo -a topology.yml
INFO:__main__:Archive file topo.tar.gz created
$ tar -tvf topo.tar.gz 
drwxr-xr-x root/root         0 2018-09-14 11:53 config/
-rw-r--r-- null/null       660 2018-09-11 15:08 topology.yml

(Optional) User-defined docker images

It is possible to create topology with arbitrary docker images. One such example is the openstack topology. Whenever a CUSTOM_IMAGE dictionary present, any device names that did not match against the well-known images (e.g. cEOS, vEOS, Host, VMX, CSR etc.), will be matched against the keys of this dictionary and, if match is found, the corresponding value will be used as an image. So in case the topology file has:

CUSTOM_IMAGE:
  search_key: docker_image

The docker-topo image matching logic will try to see if search_key in device_name.lower() and if True, will build a Generic device type with self.image == docker_image.

Example 1 - Creating a 2-node topology interconnected directly with veth links (without config)

+------+             +------+
|      |et1+-----+et2|      |
|cEOS 1|             |cEOS 2|
|      |et2+-----+et1|      |
+------+             +------+

sudo docker-topo --create topo-extra-files/examples/v2/2-node.yml

Example 2 - Creating a 3-node topology using the default docker bridge driver (with config)

+------+             +------+
|cEOS 1|et1+-----+et2|cEOS 2|
+------+             +------+
   et2                  et1
    +                    +
    |      +------+      |
    +--+et1|cEOS 3|et2+--+
           +------+

mkdir config
echo "hostname cEOS-1" > ./config/3-node_cEOS-1
echo "hostname cEOS-2" > ./config/3-node_cEOS-2
echo "hostname cEOS-3" > ./config/3-node_cEOS-3
docker-topo --create topo-extra-files/examples/v1-legacy/3-node.yml

List and connect to devices

# docker ps -a 
CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS                     PORTS                   NAMES
2315373f8741        ceosimage:latest    "/sbin/init"             About a minute ago   Up About a minute          0.0.0.0:9002->443/tcp   3-node_cEOS-3
e427def01f3a        ceosimage:latest    "/sbin/init"             About a minute ago   Up About a minute          0.0.0.0:9001->443/tcp   3-node_cEOS-2
f1a2ac8a904f        ceosimage:latest    "/sbin/init"             About a minute ago   Up About a minute          0.0.0.0:9000->443/tcp   3-node_cEOS-1


# docker exec -it 3-node_cEOS-1 Cli
cEOS-1>

Destroy a topology

docker-topo --destroy topo-extra-files/examples/3-node.yml

Troubleshooting

• If you get the following error, try renaming the topology filename to a string shorter than 15 characters

  pyroute2.netlink.exceptions.NetlinkError: (34, 'Numerical result out of range')
  

• CVP can't connect to cEOS devices - make sure that CVP is attached with at least two interfaces. The first one is always for external access and the second one if always for device management