[feature] Allow managing ZeroTier networks from OpenWISP

[pandafy]

ZeroTier Controller exposes REST API endpoints which can be used to configure the network. We can use those endpoints to allow managing ZeroTier network directly from OpenWISP.

Dependencies

• [ ] https://github.com/openwisp/openwisp-controller/issues/604

[pandafy]

Expected workflow

1. A user creates a ZeroTier VPN backend in OpenWISP at /admin/config/vpn/add/
2. A POST request is sent to https://my.zerotier.com/api/v1/network REST API endpoint. We save the networkId field returned in the response in the configuration. API documentation: https://docs.zerotier.com/central/v1#operation/newNetwork
3. A POST request is sent to https://my.zerotier.com/api/v1/network/{networkID} with the configuration set by user. This POST request is always sent whenever there is any change to the configuration of the VPN. API documentation: https://docs.zerotier.com/central/v1#operation/updateNetwork
4. Deleting a ZeroTier VPN should send a DELETE request to https://my.zerotier.com/api/v1/network/{networkID}. API documentation: https://docs.zerotier.com/central/v1#operation/deleteNetwork

https://my.zerotier.com/ in above points should be made configurable using the Host field of VPN model to support self-hosted ZeroTier controllers.

[Aryamanz29]

Note

To implement IP assignment for ZeroTier clients, we can make use of the subnet field in the VPN model, similar to the WireGuard VPN backend.

[pandafy]

Completed in https://github.com/openwisp/openwisp-controller/pull/778