anexia-it/k8s-anexia-ccm

package address

import (
    "context"
    "errors"
    "fmt"
    "net"
    "net/http"

    "github.com/go-logr/logr"
    "go.anx.io/go-anxcloud/pkg/api"
    "go.anx.io/go-anxcloud/pkg/api/types"
    corev1 "go.anx.io/go-anxcloud/pkg/apis/core/v1"
    "go.anx.io/go-anxcloud/pkg/ipam"
    v1 "k8s.io/api/core/v1"
)

type prefix struct {
    identifier string
    prefix     net.IPNet
    family     v1.IPFamily
    addresses  []net.IP
}

func newPrefix(ctx context.Context, apiclient api.API, ipamClient ipam.API, identifier string, autoDiscoveryName *string) (*prefix, error) {
    p, err := ipamClient.Prefix().Get(ctx, identifier)
    if err != nil {
        return nil, err
    }

    _, n, err := net.ParseCIDR(p.Name)
    if err != nil {
        return nil, err
    }

    ret := prefix{
        identifier: identifier,
        prefix:     *n,
        family:     v1.IPv6Protocol,
    }

    if n.IP.To4() != nil {
        ret.family = v1.IPv4Protocol
    }

    if autoDiscoveryName != nil {
        tag := fmt.Sprintf("kubernetes-lb-vip-%s", *autoDiscoveryName)
        vip, err := ret.discoverVIP(ctx, apiclient, ipamClient, tag)
        if err != nil {
            return nil, fmt.Errorf("error discovering VIP: %w", err)
        }

        if vip == nil {
            // Fall back for backwards compatibility - remove once there are no autodiscovery clusters without tagged VIPs
            vip = calculateVIP(ret.prefix)
            logger := logr.FromContextOrDiscard(ctx)
            logger.Info("Could not auto discover VIP, falling back to calculated VIP", "prefix-identifier", ret.identifier, "vip", vip.String())
        }

        ret.addresses = []net.IP{vip}
    } else {
        ret.addresses = []net.IP{calculateVIP(ret.prefix)}
    }

    return &ret, nil
}

func (p prefix) allocateAddress(ctx context.Context, fam v1.IPFamily) (net.IP, error) {
    if fam != p.family {
        return nil, errFamilyMismatch
    }

    log := logr.FromContextOrDiscard(ctx).WithValues(
        "prefix", p.prefix.String(),
        "prefix-identifier", p.identifier,
    )

    // XXX: replace this with IPAM address allocation logic once we can add and remove LoadBalancer IPs
    // See SYSENG-918 for more info.
    ip := p.addresses[0]

    log.V(1).Info(
        "allocated external IP",
        "prefix", p.prefix.String(),
        "address", ip.String(),
    )

    return ip, nil
}

func (p prefix) discoverVIP(ctx context.Context, apiClient api.API, ipamClient ipam.API, tag string) (net.IP, error) {
    logger := logr.FromContextOrDiscard(ctx)

    ctx, cancel := context.WithCancel(ctx)
    defer cancel()

    var oc types.ObjectChannel
    err := apiClient.List(ctx, &corev1.Resource{Tags: []string{tag}}, api.ObjectChannel(&oc))
    if err != nil {
        httpError := api.HTTPError{}
        // nothing is tagged with autodiscover tag -> no VIP found, but also no error
        if errors.As(err, &httpError) && httpError.StatusCode() == http.StatusUnprocessableEntity {
            err = nil
        } else {
            err = fmt.Errorf("unable to autodiscover VIP address by tag %q: %w", tag, err)
        }

        return nil, err
    }

    for retriever := range oc {
        var res corev1.Resource
        err := retriever(&res)
        if err != nil {
            return nil, fmt.Errorf("error retrieving resource: %w", err)
        }

        address, err := ipamClient.Address().Get(ctx, res.Identifier)
        if err != nil {
            logger.Error(err, "Error retrieving Address, maybe something else is tagged with %q? Ignoring this one and continuing",
                "identifier", res.Identifier,
            )
            continue
        }

        // If the address we discovered is not from the prefix for which we are allocating, skip it
        if address.PrefixID != p.identifier {
            continue
        }

        logger.V(1).Info("Found VIP Address via auto discovery", "identifier", address.ID)
        return net.ParseIP(address.Name), err
    }

    // no VIP found, but also no error
    return nil, nil

}