feat: initial release

internal/roles/dns/dns.go

@@ -0,0 +1,122 @@
+package dns
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"sync"
+
+	"git.wzray.com/homelab/mastermind/internal/config"
+	"git.wzray.com/homelab/mastermind/internal/state"
+	"git.wzray.com/homelab/mastermind/internal/types"
+	"git.wzray.com/homelab/mastermind/internal/web/client"
+	"github.com/rs/zerolog/log"
+)
+
+const hostsDir = "/etc/hosts.d/"
+
+type Role struct {
+	state  *state.RuntimeState
+	config config.DnsConfig
+	group  sync.WaitGroup
+}
+
+func New(state *state.RuntimeState, config config.DnsConfig) *Role {
+	r := &Role{
+		state:  state,
+		config: config,
+	}
+
+	return r
+}
+
+func (r *Role) updateDnsmasq(filename string, data []byte) error {
+	if err := os.WriteFile(filename, data, 0644); err != nil {
+		return fmt.Errorf("write endpoint file %q: %w", filename, err)
+	}
+
+	if err := r.reload(); err != nil {
+		return fmt.Errorf("reload dnsmasq: %w", err)
+	}
+
+	return nil
+}
+
+func parseState(state types.HostState) (string, []byte) {
+	var builder strings.Builder
+
+	for _, d := range state.Domains {
+		builder.WriteString(fmt.Sprintf("%s %s\n", state.Name, d))
+	}
+
+	return hostsDir + state.Endpoint, []byte(builder.String())
+}
+
+func (r *Role) OnStartup(ctx context.Context) error {
+	r.group.Go(func() {
+		r.syncFromRegistry()
+	})
+
+	c := r.state.Registry.OnChanged()
+	r.group.Go(func() {
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-c:
+				r.syncFromRegistry()
+			}
+		}
+	})
+
+	return nil
+}
+
+func (r *Role) syncFromRegistry() {
+	for _, n := range r.state.Registry.ByRole(types.HostRole) {
+		state, err := client.Get[types.HostState](n.Address, types.PathHostDns)
+		if err != nil {
+			log.Warn().Str("name", n.Name).Err(err).Msg("unable to get host config")
+			continue
+		}
+
+		filename, data := parseState(*state)
+		if err := r.updateDnsmasq(filename, data); err != nil {
+			log.Warn().Str("name", n.Name).Err(err).Msg("unable to update dnsmasq")
+			continue
+		}
+	}
+}
+
+func (r *Role) OnShutdown() error {
+	r.group.Wait()
+	return nil
+}
+
+func (r *Role) reload() error {
+	var err error
+
+	if r.config.UseSystemd {
+		err = exec.Command("systemctl", "reload", "dnsmasq").Run()
+	} else {
+		err = exec.Command("/etc/init.d/dnsmasq", "reload").Run()
+	}
+
+	return err
+}
+
+func (r *Role) onCallback(state types.HostState) (bool, error) {
+	filename, data := parseState(state)
+
+	if err := r.updateDnsmasq(filename, data); err != nil {
+		return false, err
+	}
+
+	return true, nil
+}
+
+func (r *Role) RegisterHandlers(rg types.Registrator) {
+	rg.Register(types.PostEndpoint(types.PathDnsCallback, r.onCallback))
+}