125 lines
2.2 KiB
Go
125 lines
2.2 KiB
Go
// Package dns provides a dns SRV selector
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package dns
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import (
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"fmt"
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"net"
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"strconv"
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"github.com/micro/go-micro/v2/client/selector"
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"github.com/micro/go-micro/v2/registry"
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)
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type dnsSelector struct {
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options selector.Options
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domain string
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}
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var (
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DefaultDomain = "local"
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)
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func (d *dnsSelector) Init(opts ...selector.Option) error {
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for _, o := range opts {
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o(&d.options)
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}
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return nil
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}
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func (d *dnsSelector) Options() selector.Options {
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return d.options
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}
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func (d *dnsSelector) Select(service string, opts ...selector.SelectOption) (selector.Next, error) {
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var srv []*net.SRV
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// check if its host:port
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host, port, err := net.SplitHostPort(service)
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// not host:port
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if err != nil {
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// lookup the SRV record
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_, srvs, err := net.LookupSRV(service, "tcp", d.domain)
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if err != nil {
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return nil, err
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}
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// set SRV records
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srv = srvs
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// got host:port
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} else {
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p, _ := strconv.Atoi(port)
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// lookup the A record
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ips, err := net.LookupHost(host)
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if err != nil {
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return nil, err
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}
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// create SRV records
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for _, ip := range ips {
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srv = append(srv, &net.SRV{
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Target: ip,
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Port: uint16(p),
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})
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}
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}
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nodes := make([]*registry.Node, 0, len(srv))
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for _, node := range srv {
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nodes = append(nodes, ®istry.Node{
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Id: node.Target,
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Address: fmt.Sprintf("%s:%d", node.Target, node.Port),
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})
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}
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services := []*registry.Service{
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{
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Name: service,
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Nodes: nodes,
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},
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}
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sopts := selector.SelectOptions{
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Strategy: d.options.Strategy,
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}
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for _, opt := range opts {
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opt(&sopts)
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}
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// apply the filters
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for _, filter := range sopts.Filters {
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services = filter(services)
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}
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// if there's nothing left, return
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if len(services) == 0 {
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return nil, selector.ErrNoneAvailable
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}
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return sopts.Strategy(services), nil
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}
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func (d *dnsSelector) Mark(service string, node *registry.Node, err error) {}
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func (d *dnsSelector) Reset(service string) {}
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func (d *dnsSelector) Close() error {
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return nil
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}
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func (d *dnsSelector) String() string {
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return "dns"
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}
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func NewSelector(opts ...selector.Option) selector.Selector {
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options := selector.Options{
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Strategy: selector.Random,
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}
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for _, o := range opts {
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o(&options)
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}
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return &dnsSelector{options: options, domain: DefaultDomain}
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}
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