isle/go/daemon/children/dnsmasq.go

package children

import (
	"context"
	"fmt"
	"isle/bootstrap"
	"isle/daemon/daecommon"
	"isle/dnsmasq"
	"path/filepath"

	"code.betamike.com/micropelago/pmux/pmuxlib"
	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
)

func dnsmasqWriteConfig(
	ctx context.Context,
	logger *mlog.Logger,
	runtimeDirPath string,
	networkConfig daecommon.NetworkConfig,
	hostBootstrap bootstrap.Bootstrap,
) (
	string, bool, error,
) {
	hosts := make([]dnsmasq.ConfDataHost, 0, len(hostBootstrap.Hosts))
	for _, host := range hostBootstrap.Hosts {
		hosts = append(hosts, dnsmasq.ConfDataHost{
			Name: string(host.Name),
			IP:   host.IP().String(),
		})
	}

	var (
		confPath = filepath.Join(runtimeDirPath, "dnsmasq.conf")
		confData = dnsmasq.ConfData{
			Resolvers: networkConfig.DNS.Resolvers,
			Domain:    hostBootstrap.NetworkCreationParams.Domain,
			IP:        hostBootstrap.ThisHost().IP().String(),
			Hosts:     hosts,
		}
	)

	changed, err := dnsmasq.WriteConfFile(ctx, logger, confPath, confData)
	if err != nil {
		return "", false, fmt.Errorf(
			"writing dnsmasq.conf to %q: %w", confPath, err,
		)
	}

	return confPath, changed, nil
}

// TODO consider a shared dnsmasq across all the daemon's networks.
// This would have a few benefits:
//   - Less processes, less problems
//   - Less configuration for the user in the case of more than one network.
//   - Can listen on 127.0.0.x:53, rather than on the nebula address. This
//     allows DNS to come up before nebula, which is helpful when nebula depends
//     on DNS.
func dnsmasqPmuxProc(
	ctx context.Context,
	logger *mlog.Logger,
	runtimeDirPath, binDirPath string,
	networkConfig daecommon.NetworkConfig,
	hostBootstrap bootstrap.Bootstrap,
) (
	*pmuxlib.Process, error,
) {
	confPath, _, err := dnsmasqWriteConfig(
		ctx, logger, runtimeDirPath, networkConfig, hostBootstrap,
	)
	if err != nil {
		return nil, fmt.Errorf(
			"writing dnsmasq config: %w", err,
		)
	}

	cfg := pmuxlib.ProcessConfig{
		Cmd:  filepath.Join(binDirPath, "dnsmasq"),
		Args: []string{"-d", "-C", confPath},
	}
	cfg = withPmuxLoggers(ctx, logger, "dnsmasq", cfg)

	return pmuxlib.NewProcess(cfg), nil
}