An example YANG data model

We are going to start by writing a simple YANG data model that we will use throughout the remainder of this tutorial.

Our data model manages the interfaces on a device. It contains a list of interfaces, and each interface has a name, an IPv4 address, and counters for the number of sent and received packets.

In real life, the data models for managing interfaces (RFC 8343) and for managing IP addresses (RFC 8344) are way more complex, but we are using a simplistic data model in this tutorial to keep the example code short and easy to understand.

Here is our data model (you can find it in this repository in the file interfaces.yang):

module interfaces {

    namespace "http://remoteautonomy.com/yang-schemas/interfaces";
    prefix intf;

    organization
      "Remote Autonomy";

    contact
      "Bruno Rijsman
       brunorijsman@remoteautonomy.com";

    description
        "A simplistic tutorial data model for interfaces on a device.";

    revision 2022-03-12 {
        description
          "Initial revision.";
    }

    container interfaces {
        description
          "Interface parameters.";

        list interface {
            key "name";
            description
              "The list of interfaces on the device.";

            leaf name {
                type string;
                description
                  "The name of the interface.";
            }

            leaf ipv4-address {
                type string {
                    pattern
                      '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
                    + '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])';
                }
                description
                  "The IPv4 address of the interface.";
            }

            leaf sent-packets {
                type uint64;
                config false;
                description
                  "The number of IPv4 packets sent out over this interface";
            }

            leaf received-packets {
                type uint64;
                config false;
                description
                  "The number of IPv4 packets received over this interface";
            }
        }
    }
}

There is also a file called bad-interfaces.yang that contains some errors on purpose so that we can demonstrate the error messages produced by the various YANG validation tools.

TODO: Add an RPC to the data model