Network NG

This document tries to describe the details of the network-ng data model and how all the pieces are combined.

Data Model

Overall Approach

Y2Network::Config and other associated classes represent the network configuration in a backend agnostic way. It should not matter whether you are using sysconfig files, NetworkManager or networkd.

The systems' configuration is read using configuration readers, which are special classes which implements the logic to find out the details and build a proper Y2Network::Config object. Once the wanted modifications are performed to this configuration object, it could be written in the filesystem by using a configuration writer.

             +--------+             +---------+
reader ----> | config | -- user --> | config' |----> writer
  ^          +--------+             +---------+        |
  |                                                    |
  |                     +--------+                     |
  +---------------------| system |<--------------------+
                        +--------+

Obviously, we should implement configuration readers and writers for whathever backend we would like to support. At this point of time, only Sysconfig and Autoinst are supported.

The Configuration Classes

Y2Network::Config offers and API to deal with network configuration, but it collaborates with other classes. These are the most relevant ones:

Multi-Backend Support

As mentioned above, Y2Network is designed to support different backends. It is expected to implement a reader and a writer for each backend (except for AutoYaST, which is an special case). The reader will be responsible for checking the system's configuration and building a Y2Network::Config object, containing interfaces, configurations, routes, etc. On the other hand, the writer will be responsible for updating the system using that configuration object.

As a developer, you rarely will need to access to readers/writers because Yast::Lan already offers an API to read and write the configuration. See the Accessing the Configuration section for further details.

Sysconfig

The sysconfig backend support is composed by these files:

src/lib/y2network/sysconfig

Y2Network::Sysconfig::ConfigReader and Y2Network::Sysconfig::ConfigWriter are the reader and writer classes. Each of them cooperates with a set of ancillary classes in order to get the job done.

Y2Network::Sysconfig::DNSReader, Y2Network::Sysconfig::InterfacesReader and Y2Network::Sysconfig::ConnectionConfigReader are involved in reading the configuration. The logic to read the configuration for a connection (e.g., ifcfg-eth0, ifcfg-wlan0, etc.) is implemented in a set of smaller classes (one for each time of connection) under Y2Network::Sysconfig::ConnectionConfigReaders.

Y2Network::Sysconfig::InterfacesWriter, Y2Network::Sysconfig::DNSWriter and Y2Network::Sysconfig::ConnectionConfigWriter, including smaller classes under Y2Network::Sysconfig::ConnectionConfigWriters, are involved in writing the configuration.

Last but not least, there are additional classes like Y2Network::Sysconfig::RoutesFile and Y2Network::Sysconfig::InterfaceFile which abstract the details of reading/writing ifroute and ifcfg files.

AutoYaST

AutoYaST is a special case in the sense that it reads the information from a profile, instead of using the running system as reference. Additionally, it does not implement a writer because the configuration will be written using a different backend (like sysconfig).

src/lib/y2network/autoinst/

Another important aspect of the AutoYaST support is that, instead of using a big Hash, the information included in the profile is handled through a set of classes in Y2Network::AutoinstProfile (see Y2Network::AutoinstProfile::NetworkingSection). However, there is some preprocessing that is still done using the original Hash.

Accessing the Configuration

The Yast::Lan module is still the entry point to read and write the network configuration. Basically, it keeps two configuration objects, one for the running system and another want for the wanted configuration.

Yast.import "Lan"
Yast::Lan.read(:cache)
system_config = Yast::Lan.system_config
yast_config = Yast::Lan.yast_config
system_config == yast_config # => true
# let's change IP forwarding settings
yast_config.routing.forward_ipv4 = !system_config.routing.forward_ipv4
system_config == yast_config # => false
# write the new configuration
Yast::Lan.Write

Any change you want to apply to the running system should be performed by modifying the yast_config and writing the changes.

New UI layer

Interface Configuration Builders

In the old code, there was no clear separation between UI and business logic. In order to improve the situation, we introduced the concept of interface configuration builders.

We already have implemented support for several interface types. You can find them under the Y2Network::InterfaceConfigBuilders namespace.

Widgets

The user interaction is driven by a set of sequences, which determines the dialogs are shown to the user. Each of those dialogs contain a set of widgets, usually grouped in tabs. The content of the dialog depends on the interface type.

Below you can find some pointers to relevant sequences, dialogs and widgets: