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messagebus.go
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messagebus.go
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package messagebus
import (
"crypto/tls"
"encoding/json"
"errors"
"fmt"
"net/url"
"sync/atomic"
"time"
"code.cloudfoundry.org/lager/v3"
"code.cloudfoundry.org/route-registrar/config"
"github.com/nats-io/nats.go"
)
//go:generate counterfeiter . MessageBus
type MessageBus interface {
Connect(servers []config.MessageBusServer, tlsConfig *tls.Config) error
SendMessage(subject string, host string, route config.Route, privateInstanceId string) error
Close()
}
type msgBus struct {
natsHost *atomic.Value
natsConn *nats.Conn
availabilityZone string
logger lager.Logger
}
type Message struct {
URIs []string `json:"uris"`
Host string `json:"host"`
Protocol string `json:"protocol,omitempty"`
Port *int `json:"port,omitempty"`
TLSPort *int `json:"tls_port,omitempty"`
Tags map[string]string `json:"tags"`
RouteServiceUrl string `json:"route_service_url,omitempty"`
PrivateInstanceId string `json:"private_instance_id"`
ServerCertDomainSAN string `json:"server_cert_domain_san,omitempty"`
AvailabilityZone string `json:"availability_zone,omitempty"`
Options map[string]string `json:"options,omitempty"`
}
const LoadBalancingAlgorithm string = "lb_algo"
func NewMessageBus(logger lager.Logger, availabilityZone string) MessageBus {
return &msgBus{
logger: logger,
natsHost: &atomic.Value{},
availabilityZone: availabilityZone,
}
}
func (m *msgBus) Connect(servers []config.MessageBusServer, tlsConfig *tls.Config) error {
var natsServers []string
var natsHosts []string
for _, server := range servers {
natsServers = append(
natsServers,
fmt.Sprintf("nats://%s:%s@%s", server.User, server.Password, server.Host),
)
natsHosts = append(natsHosts, server.Host)
}
opts := nats.DefaultOptions
opts.Servers = natsServers
opts.TLSConfig = tlsConfig
opts.PingInterval = 20 * time.Second
opts.ClosedCB = func(conn *nats.Conn) {
m.logger.Error("nats-connection-closed", errors.New("unexpected nats conn closed"), lager.Data{"nats-host": m.natsHost.Load()})
}
opts.DisconnectedCB = func(conn *nats.Conn) {
m.logger.Info("nats-connection-disconnected", lager.Data{"nats-host": m.natsHost.Load()})
}
opts.ReconnectedCB = func(conn *nats.Conn) {
natsHost, err := parseNatsUrl(conn.ConnectedUrl())
if err != nil {
m.logger.Error("nats-url-parse-failed", err, lager.Data{"nats-host": natsHost})
}
m.natsHost.Store(natsHost)
m.logger.Info("nats-connection-reconnected", lager.Data{"nats-host": m.natsHost.Load()})
}
natsConn, err := opts.Connect()
if err != nil {
m.logger.Error("nats-connection-failed", err, lager.Data{"nats-hosts": natsHosts})
return err
}
natsHost, err := parseNatsUrl(natsConn.ConnectedUrl())
if err != nil {
m.logger.Error("nats-url-parse-failed", err, lager.Data{"nats-host": natsHost})
}
m.natsHost.Store(natsHost)
m.logger.Info("nats-connection-successful", lager.Data{"nats-host": m.natsHost.Load()})
m.natsConn = natsConn
return nil
}
func (m msgBus) SendMessage(subject string, host string, route config.Route, privateInstanceId string) error {
m.logger.Debug("creating-message", lager.Data{"subject": subject, "host": host, "route": route, "privateInstanceId": privateInstanceId})
routeOptions := m.mapRouteOptions(route)
msg := &Message{
URIs: route.URIs,
Host: host,
Port: route.Port,
Protocol: route.Protocol,
TLSPort: route.TLSPort,
Tags: route.Tags,
RouteServiceUrl: route.RouteServiceUrl,
ServerCertDomainSAN: route.ServerCertDomainSAN,
PrivateInstanceId: privateInstanceId,
AvailabilityZone: m.availabilityZone,
Options: routeOptions,
}
json, err := json.Marshal(msg)
if err != nil {
// Untested as we cannot force json.Marshal to return error.
return err
}
m.logger.Debug("publishing-message", lager.Data{"msg": string(json)})
return m.natsConn.Publish(subject, json)
}
func (m msgBus) mapRouteOptions(route config.Route) map[string]string {
if route.Options != nil {
routeOptions := make(map[string]string)
if route.Options.LoadBalancingAlgorithm != "" {
routeOptions[LoadBalancingAlgorithm] = string(route.Options.LoadBalancingAlgorithm)
}
return routeOptions
}
return nil
}
func (m msgBus) Close() {
m.natsConn.Close()
}
func parseNatsUrl(natsUrl string) (string, error) {
natsURL, err := url.Parse(natsUrl)
natsHostStr := ""
if err != nil {
return "", err
} else {
natsHostStr = natsURL.Host
}
return natsHostStr, nil
}