dns: introduce initial DNS Manager

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/dns/manager.go

@@ -0,0 +1,173 @@
+package dns
+
+import (
+	"context"
+	"errors"
+	"io/fs"
+	"net/netip"
+	"strings"
+
+	"darvaza.org/core"
+	"darvaza.org/slog"
+	"git.jpi.io/amery/jpictl/pkg/cluster"
+	"golang.org/x/net/publicsuffix"
+)
+
+// Manager is a DNS Manager instance
+type Manager struct {
+	domain  string
+	suffix  string
+	zones   map[string]*Zone
+	regions map[string][]string
+
+	p Provider
+	l slog.Logger
+}
+
+// ManagerOption configures a Manager
+type ManagerOption func(*Manager) error
+
+func newErrorManagerOption(err error, hint string) ManagerOption {
+	return func(*Manager) error {
+		return core.Wrap(err, hint)
+	}
+}
+
+// WithProvider attaches a libdns Provider to the Manager
+func WithProvider(p Provider) ManagerOption {
+	var err error
+
+	if p == nil {
+		p, err = DefaultDNSProvider()
+	}
+
+	if err != nil {
+		return newErrorManagerOption(err, "WithProvider")
+	}
+
+	return func(mgr *Manager) error {
+		mgr.p = p
+		return nil
+	}
+}
+
+// WithLogger attaches a logger to the Manager
+func WithLogger(log slog.Logger) ManagerOption {
+	if log == nil {
+		log = cluster.DefaultLogger()
+	}
+
+	return func(mgr *Manager) error {
+		mgr.l = log
+		return nil
+	}
+}
+
+func (mgr *Manager) setDefaults() error {
+	var opts []ManagerOption
+
+	if mgr.l == nil {
+		opts = append(opts, WithLogger(nil))
+	}
+
+	if mgr.domain == "" || mgr.suffix == "" {
+		return errors.New("domain not specified")
+	}
+
+	for _, opt := range opts {
+		if err := opt(mgr); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// WithDomain specifies where the manager operates
+func WithDomain(domain string) ManagerOption {
+	base, err := publicsuffix.EffectiveTLDPlusOne(domain)
+	if err != nil {
+		return newErrorManagerOption(err, "publicsuffix")
+	}
+
+	suffix := strings.TrimSuffix(domain, base)
+	if suffix != "" {
+		suffix = "." + suffix[:len(suffix)-1]
+	}
+
+	return func(mgr *Manager) error {
+		mgr.domain = base
+		mgr.suffix = suffix
+		return nil
+	}
+}
+
+// NewManager creates a DNS manager with the
+func NewManager(opts ...ManagerOption) (*Manager, error) {
+	mgr := &Manager{
+		zones:   make(map[string]*Zone),
+		regions: make(map[string][]string),
+	}
+
+	for _, opt := range opts {
+		if err := opt(mgr); err != nil {
+			return nil, err
+		}
+	}
+
+	if err := mgr.setDefaults(); err != nil {
+		return nil, err
+	}
+	return mgr, nil
+}
+
+// AddHost registers a host
+func (mgr *Manager) AddHost(_ context.Context, zone string, id int,
+	active bool, addrs ...netip.Addr) error {
+	//
+	if zone == "" || id <= 0 {
+		return fs.ErrInvalid
+	}
+
+	z, ok := mgr.zones[zone]
+	if !ok {
+		z = &Zone{
+			Name:  zone,
+			Hosts: make(map[int]*Host),
+		}
+
+		mgr.zones[zone] = z
+	}
+
+	p := &Host{
+		zone:   z,
+		ID:     id,
+		Active: active,
+		Addrs:  SortAddrSlice(addrs),
+	}
+	z.Hosts[id] = p
+
+	if log, ok := mgr.l.Debug().WithEnabled(); ok {
+		log.WithField("subsystem", "dns").
+			WithField("zone", zone).
+			WithField("host", p.String()).
+			WithField("active", active).
+			Print()
+	}
+
+	return nil
+}
+
+// AddRegion specifies a new region and the zones it contains
+func (mgr *Manager) AddRegion(_ context.Context, region string, zones ...string) error {
+	mgr.regions[region] = append(mgr.regions[region], zones...)
+
+	if log, ok := mgr.l.Debug().WithEnabled(); ok {
+		for _, zoneName := range zones {
+			log.WithField("subsystem", "dns").
+				WithField("region", region).
+				WithField("zone", zoneName).Print()
+		}
+	}
+
+	return nil
+}