Annet - network configuration utility

The system contains network appliance config generators written in Python with optional use of text preprocessors (Jinja2, Mako). Huawei, Cisco IOS, Cisco NX-OS, Cisco IOS-XR, Juniper, as well as devices configured via separate config files (Linux, FreeBSD, Cumulus) are supported.

annet has a number of modes (subcommands):

• annet gen - generates the entire config for the specified devices or specified parts of it
• annet diff - first does gen and then builds diff with current config version
• annet patch - first does diff and then generates a list of commands to apply diff on the device

Usage help can be obtained by calling annet -h or for a specific command, such as annet gen -h.

Overview

annet gen

The annet_generators directory contains many files called generators. A generator takes information about the switch as input and returns the configuration. The part of the config that the generator is responsible for is specified in the generator's acl function. If a generator returns a configuration that does not fall under acl, an exception will be thrown.

Example generator:

from annet.generators import PartialGenerator

class Mtu(PartialGenerator):
    TAGS = ["mtu"]
    def acl_cisco(self, _):
        return "system mtu jumbo"

    def run_cisco(self, device):
        yield "system mtu jumbo %d" % 9000

And an example of calling annet:

annet gen -g mtu sw6-i1
# -------------------- sw6-i1.cfg --------------------
system mtu jumbo 9000

Method acl_cisco defines scope of the generator, which commands and block it controls. The option -g mtu means that only generators with the mtu element in the TAGS variable should be called. If no tag is specified, all generators will be executed.

annet diff

If we were configuring the switch from scratch, these options would be enough, but in our reality we need to be able not only to generate the desired configuration, but also to be able to bring the current configuration to the desired one. To do this, you need to be able to delete an outdated configuration and correctly add a new one. The diff module, which implements some tricky logic, is responsible for this work. This logic is defined in the rulebook/texts/VENDOR folder.

Example diff:

# -------------------- sw1-i38.cfg --------------------
  acl number 2610
- rule 40 permit source 10.11.170.150 0
+ rule 12 permit source 10.11.133.81 0

annet patch

Next, you need to create a list of commands from the resulting diff. The patch module is responsible for this. It receives the diff, runs the logic specified in rulebook/texts/VENDOR and returns the list of commands. Let's take the above diff. It says to remove the command rule 40 permit source 10.11.170.150 0 and add rule 12 permit source 10.11.133.81 0. Basic command delete logic for huawei is adding undo to the command. So the undo command will look like this: undo rule 40 permit source 10.11.170.150 0```, but this is an invalid command. In case of canceling acl rules, you need to execute undo rule N. So you need to write the undo logic for the rule ```` command in the ``acl ``` block. Here is the part of rulebook/texts/huawei.rul responsible for this:

acl name *
	rule * %logic=huawei.misc.undo_redo

The asterisk here means that the key argument of the undo_redo function will contain the first word after rule, namely the rule number.

Here, the undo_redo function from the file in rulebook/huawei/misc.py is used to generate the command to remove rules in acl.

def undo_redo(rule, key, diff, **_):
    ...

Now calling ```annet patch -g snmp sw1-i38```` returns the correct set of commands.

acl number 2610
  undo rule 40
  rule 12 permit source 10.11.133.81 0
  quit

Configuration

The path to the configuration file is searched in following order:

• ANN_CONTEXT_CONFIG_PATH env.
• ~/.annet/context.yml.
• annet/configs/context.yml.

Config example:

connection:
  default:
    login: ~
    passwords: ~

generators:
  default:
    - my_annet_generators.example

storage:
  default:
    adapter: annet.adapters.file.provider
    params:
      path: /path/to/file

context:
  default:
    connection: default
    generators: default
    storage: default

selected_context: default

Environment variable ANN_SELECTED_CONTEXT can be used to override selected_context parameter.

Storages

Storages provide information about devices like FQDN, interface and so on.

Netbox storage

Provide NETBOX_URL and NETBOX_TOKEN environment variable to setup data source.

export NETBOX_URL="https://demo.netbox.dev"
export NETBOX_TOKEN="1234567890abcdef01234567890abcdef0123456"

File storage

storage:
  default:
    adapter: annet.adapters.file.provider
    params:
      path: /path/to/file

cat /path/to/file:

devices:
  - fqdn: myhost.yndx.net
    vendor: mikrotik
    interfaces:
      - name: eth0
        description: test

Extending

Annet uses Entry Points mechanism for customization. For example, you can implement the Storage interface on top of your favorite inventory system.