json2netns 2021.9.20

JSON parsing Linux Network Namespace (netns) topology builder.

json2netns

JSON parsing Linux Network Namespace (netns) topology builder.

Install

From PyPI:

• pip install json2netns

From GitHub:

• pip install git+git://github.com/cooperlees/json2netns

Concepts

• What is a Linux Namespace - aka NetNS?
  • https://blog.scottlowe.org/2013/09/04/introducing-linux-network-namespaces/
• WHat is JSON?
  • https://www.json.org/

The script takes a JSON config file and drives namespace creation from that JSON toplogy file. Lets look at the following simple two network namespace topology:

We have two namespaces that have 1 direct connection via a veth. It also has a OOB (Out of Band) set of interfaces that allow the main Linux Network Namespace to communicate with the netns directly.

• By default it even bridges with a physical interface to allow external packets to be routed into the netns if desired from a physical NIC.

Configuration

The above topology is represented by sample.json. This config is also used by unittests to ensure correct functioning. We can add to it over time as users require more features.

Small 1 NS Example JSON Config

{
    "namespaces": {
        "left": {
            "id": 1,
            "interfaces": {
                "left0": {
                    "prefixes": ["fd00::1/64", "10.1.1.1/24"],
                    "peer_name": "right0",
                    "type": "veth"
                },
                "lo": {
                    "prefixes": ["fd00:1::/64", "10.6.9.1/32"],
                    "type": "loopback"
                }
            },
            "oob": false,
            "routes": {
                "route1": {
                    "dest_prefix" : "10.6.9.6/32",
                    "next_hop_ip" : "10.1.1.2",
                    "egress_if_name" : ""
                },
                "route2": {
                    "dest_prefix" : "fd00:6::/64",
                    "next_hop_ip" : "fd00::2",
                    "egress_if_name" : ""
                }
            }
        }
    },
    "oob": {},
    "physical_int": ""
}

Usage

After installing just point json2netns at a valid config file and run as root (in the future we could make it capability aware too - PR Welcome!).

• usage: json2netns [-h] [-d] [--validate] [--workers WORKERS] config action

Actions

• create: Create the interfaces and namespaces + bring interfaces up
• check: Print the interface addressing + v4/6 routing tables to stdout
• delete: Remove the namespaces and all interfaces

Development

The code has attempted to be object oriented first. Please try to use inheritance and keep new interface types sub classes of Interface etc. for all code additions.

Development 'editable' Install

python3 -m venv [--upgrade-deps] /tmp/tj
/tmp/tj/bin/pip install -r requirements_test.txt
/tmp/tj/bin/pip install -e .

Run Tests

For testing we use ptr.

/tmp/tj/bin/ptr [-k] [--print-cov] [--debug]

• -k: keep venv ptr creates
• --print-cov: handy to see what coverage is on all files
• --debug: Handy to see all commands run so you can run a step manually