kvm2: Create, Get, Delete and ListByTag with the contract tests

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

internal/provider/kvm2/get.go

@@ -0,0 +1,127 @@
+package kvm2
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/digitalocean/go-libvirt"
+	"github.com/go-logr/logr"
+
+	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider"
+)
+
+// Get is spec entries 7 to 9: look the domain up by name, read the mark
+// back, then state and address. Only ErrNoDomain becomes NotFound; every
+// other failure is classified, never guessed.
+func (p *Provider) Get(ctx context.Context, providerID string) (*provider.Instance, error) {
+	hostName, name, err := parseProviderID(providerID)
+	if err != nil {
+		return nil, provider.Wrap(provider.ErrPermanent, "get", p.name, providerID, err)
+	}
+	host, err := p.host(hostName)
+	if err != nil {
+		return nil, p.wrapErr("get", providerID, err)
+	}
+	log := p.logger(ctx).WithValues("host", host.Name, "name", name)
+	be, err := p.hosts.get(ctx, host)
+	if err != nil {
+		logAPIError(log, "get", err)
+		return nil, p.wrapErr("get", providerID, err)
+	}
+	inst, err := get(ctx, log, be, host.Name, name)
+	if err != nil {
+		if hasCode(err, libvirt.ErrNoDomain) {
+			log.V(1).Info("kvm2 domain not found")
+		} else {
+			logAPIError(log, "get", err)
+		}
+		return nil, p.wrapErr("get", providerID, err)
+	}
+	log.V(1).Info("kvm2 domain fetched", "state", inst.State, "ip", inst.IP, "uid", inst.UID)
+	return inst, nil
+}
+
+func get(ctx context.Context, log logr.Logger, be backend, hostName, name string) (*provider.Instance, error) {
+	dom, err := be.DomainLookupByName(ctx, name)
+	if err != nil {
+		return nil, fmt.Errorf("looking up domain %s: %w", name, err)
+	}
+	meta, err := readMetadata(ctx, be, dom)
+	if err != nil {
+		return nil, err
+	}
+	inst, err := inspect(ctx, log, be, hostName, dom, meta)
+	if err != nil {
+		return nil, err
+	}
+	return &inst, nil
+}
+
+// readMetadata returns the kvm2 mark of a domain, or the zero value (not
+// managed, empty UID) when the domain carries none. A mark that does not
+// parse is Permanent, from parseInstanceMetadata.
+func readMetadata(ctx context.Context, be backend, dom libvirt.Domain) (instanceMetadata, error) {
+	raw, err := be.DomainGetMetadata(ctx, dom, int32(libvirt.DomainMetadataElement), libvirt.OptString{metadataURI}, libvirt.DomainAffectCurrent)
+	if hasCode(err, libvirt.ErrNoDomainMetadata) {
+		return instanceMetadata{}, nil
+	}
+	if err != nil {
+		return instanceMetadata{}, fmt.Errorf("reading metadata of domain %s: %w", dom.Name, err)
+	}
+	return parseInstanceMetadata(raw)
+}
+
+// inspect builds the Instance from the backend's state and, for an active
+// domain, its discovered address.
+func inspect(ctx context.Context, log logr.Logger, be backend, hostName string, dom libvirt.Domain, meta instanceMetadata) (provider.Instance, error) {
+	state, _, err := be.DomainGetState(ctx, dom, 0)
+	if err != nil {
+		return provider.Instance{}, fmt.Errorf("reading state of domain %s: %w", dom.Name, err)
+	}
+	s := libvirt.DomainState(state)
+	var ip string
+	if isActive(s) {
+		if ip, err = address(ctx, log, be, dom); err != nil {
+			return provider.Instance{}, err
+		}
+	}
+	return provider.Instance{
+		ID:        formatProviderID(hostName, dom.Name),
+		IP:        ip,
+		State:     mapState(s, ip),
+		UID:       meta.UID,
+		CreatedAt: meta.createdAt(),
+	}, nil
+}
+
+// addressSources is the discovery order of spec entry 7: the guest agent
+// answers where the host's ARP table never sees guest traffic.
+var addressSources = []struct {
+	name string
+	src  libvirt.DomainInterfaceAddressesSource
+}{
+	{"agent", libvirt.DomainInterfaceAddressesSrcAgent},
+	{"arp", libvirt.DomainInterfaceAddressesSrcArp},
+}
+
+// address returns the first usable IPv4 from the first source that yields
+// one, or "" for "no address yet". A source that fails is logged and
+// skipped; only ctx ending is an error, so a cancelled Get does not read
+// as Provisioning.
+func address(ctx context.Context, log logr.Logger, be backend, dom libvirt.Domain) (string, error) {
+	for _, s := range addressSources {
+		ifaces, err := be.DomainInterfaceAddresses(ctx, dom, uint32(s.src), 0)
+		if err != nil {
+			if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
+				return "", fmt.Errorf("reading addresses of domain %s: %w", dom.Name, err)
+			}
+			log.V(2).Info("no addresses from source", "source", s.name, "error", err.Error())
+			continue
+		}
+		if ip := firstIPv4(ifaces); ip != "" {
+			return ip, nil
+		}
+	}
+	return "", nil
+}