Method Build

internal/resolver/dns/dns_resolver.go:119–155

Build creates and starts a DNS resolver that watches the name resolution of the target.

(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions)

// Build creates and starts a DNS resolver that watches the name resolution of
// the target.
func (b *dnsBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
	host, port, err := parseTarget(target.Endpoint(), defaultPort)
	if err != nil {
		return nil, err
	}

	// IP address.
	if ipAddr, err := formatIP(host); err == nil {
		addr := []resolver.Address{{Addr: ipAddr + ":" + port}}
		cc.UpdateState(resolver.State{
			Addresses: addr,
			Endpoints: []resolver.Endpoint{{Addresses: addr}},
		})
		return deadResolver{}, nil
	}

	// DNS address (non-IP).
	ctx, cancel := context.WithCancel(context.Background())
	d := &dnsResolver{
		host:                host,
		port:                port,
		ctx:                 ctx,
		cancel:              cancel,
		cc:                  cc,
		rn:                  make(chan struct{}, 1),
		enableServiceConfig: envconfig.EnableTXTServiceConfig && !opts.DisableServiceConfig,
	}

	d.resolver, err = internal.NewNetResolver(target.URL.Host)
	if err != nil {
		return nil, err
	}

	d.wg.Add(1)
	go d.watcher()
	return d, nil
}

// Scheme returns the naming scheme of this resolver builder, which is "dns".
func (b *dnsBuilder) Scheme() string {