micro/network/proxy/mucp/mucp.go
2019-07-10 07:47:17 +01:00

351 lines
7.3 KiB
Go

// Package mucp transparently forwards the incoming request using a go-micro client.
package mucp
import (
"context"
"io"
"os"
"strings"
"sync"
"github.com/micro/go-micro/client"
"github.com/micro/go-micro/client/selector"
"github.com/micro/go-micro/codec"
"github.com/micro/go-micro/codec/bytes"
"github.com/micro/go-micro/config/options"
"github.com/micro/go-micro/network/proxy"
"github.com/micro/go-micro/network/router"
"github.com/micro/go-micro/server"
pb "github.com/micro/go-micro/network/router/proto"
"github.com/micro/go-micro/network/router/table"
)
// Proxy will transparently proxy requests to an endpoint.
// If no endpoint is specified it will call a service using the client.
type Proxy struct {
// embed options
options.Options
// Endpoint specified the fixed service endpoint to call.
Endpoint string
// The client to use for outbound requests
Client client.Client
// The router for routes
Router router.Router
// The router service client
RouterService pb.RouterService
// A fib of routes service:address
sync.RWMutex
Routes map[string][]table.Route
}
// read client request and write to server
func readLoop(r server.Request, s client.Stream) error {
// request to backend server
req := s.Request()
for {
// get data from client
// no need to decode it
body, err := r.Read()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
// get the header from client
hdr := r.Header()
msg := &codec.Message{
Type: codec.Request,
Header: hdr,
Body: body,
}
// write the raw request
err = req.Codec().Write(msg, nil)
if err == io.EOF {
return nil
} else if err != nil {
return err
}
}
}
func (p *Proxy) getRoute(service string) ([]string, error) {
// converts routes to just addresses
toNodes := func(routes []table.Route) []string {
var nodes []string
for _, node := range routes {
nodes = append(nodes, node.Gateway)
}
return nodes
}
// lookup the route cache first
p.RLock()
routes, ok := p.Routes[service]
// got it!
if ok {
p.RUnlock()
return toNodes(routes), nil
}
p.RUnlock()
// route cache miss, now lookup the router
// if it does not exist, don't error out
// the proxy will just hand off to the client
// and try the registry
// in future we might set a default gateway
if p.Router != nil {
// lookup the router
routes, err := p.Router.Lookup(
table.NewQuery(table.QueryService(service)),
)
if err != nil {
return nil, err
}
p.Lock()
if p.Routes == nil {
p.Routes = make(map[string][]table.Route)
}
p.Routes[service] = routes
p.Unlock()
return toNodes(routes), nil
}
// we've tried getting cached routes
// we've tried using the router
addr := os.Getenv("MICRO_ROUTER_ADDRESS")
name := os.Getenv("MICRO_ROUTER")
// no router is specified we're going to set the default
if len(name) == 0 && len(addr) == 0 {
p.Router = router.DefaultRouter
go p.Router.Advertise()
// recursively execute getRoute
return p.getRoute(service)
}
if len(name) == 0 {
name = "go.micro.router"
}
// lookup the remote router
var addrs []string
// set the remote address if specified
if len(addr) > 0 {
addrs = append(addrs, addr)
} else {
// we have a name so we need to check the registry
services, err := p.Client.Options().Registry.GetService(name)
if err != nil {
return nil, err
}
for _, service := range services {
for _, node := range service.Nodes {
addrs = append(addrs, node.Address)
}
}
}
// no router addresses available
if len(addrs) == 0 {
return nil, selector.ErrNoneAvailable
}
var pbRoutes *pb.LookupResponse
var gerr error
// set default client
if p.RouterService == nil {
p.RouterService = pb.NewRouterService(name, p.Client)
}
// TODO: implement backoff and retries
for _, addr := range addrs {
// call the router
proutes, err := p.RouterService.Lookup(context.Background(), &pb.LookupRequest{
Query: &pb.Query{
Service: service,
},
}, client.WithAddress(addr))
if err != nil {
gerr = err
continue
}
// set routes
pbRoutes = proutes
break
}
// errored out
if gerr != nil {
return nil, gerr
}
// no routes
if pbRoutes == nil {
return nil, selector.ErrNoneAvailable
}
// convert from pb to []*router.Route
for _, r := range pbRoutes.Routes {
routes = append(routes, table.Route{
Service: r.Service,
Address: r.Address,
Gateway: r.Gateway,
Network: r.Network,
Link: r.Link,
Metric: int(r.Metric),
})
}
return toNodes(routes), nil
}
// ServeRequest honours the server.Router interface
func (p *Proxy) ServeRequest(ctx context.Context, req server.Request, rsp server.Response) error {
// set default client
if p.Client == nil {
p.Client = client.DefaultClient
}
// service name
service := req.Service()
endpoint := req.Endpoint()
var addresses []string
// call a specific backend endpoint either by name or address
if len(p.Endpoint) > 0 {
// address:port
if parts := strings.Split(p.Endpoint, ":"); len(parts) > 1 {
addresses = []string{p.Endpoint}
} else {
// get route for endpoint from router
addr, err := p.getRoute(p.Endpoint)
if err != nil {
return err
}
// set the address
addresses = addr
// set the name
service = p.Endpoint
}
} else {
// no endpoint was specified just lookup the route
// get route for endpoint from router
addr, err := p.getRoute(service)
if err != nil {
return err
}
addresses = addr
}
var opts []client.CallOption
// set address if available
if len(addresses) > 0 {
opts = append(opts, client.WithAddress(addresses...))
}
// read initial request
body, err := req.Read()
if err != nil {
return err
}
// create new request with raw bytes body
creq := p.Client.NewRequest(service, endpoint, &bytes.Frame{body}, client.WithContentType(req.ContentType()))
// create new stream
stream, err := p.Client.Stream(ctx, creq, opts...)
if err != nil {
return err
}
defer stream.Close()
// create client request read loop
go readLoop(req, stream)
// get raw response
resp := stream.Response()
// create server response write loop
for {
// read backend response body
body, err := resp.Read()
if err == io.EOF {
return nil
} else if err != nil {
return err
}
// read backend response header
hdr := resp.Header()
// write raw response header to client
rsp.WriteHeader(hdr)
// write raw response body to client
err = rsp.Write(body)
if err == io.EOF {
return nil
} else if err != nil {
return err
}
}
return nil
}
// NewSingleHostProxy returns a proxy which sends requests to a single backend
func NewSingleHostProxy(endpoint string) *Proxy {
return &Proxy{
Options: options.NewOptions(),
Endpoint: endpoint,
}
}
// NewProxy returns a new proxy which will route based on mucp headers
func NewProxy(opts ...options.Option) proxy.Proxy {
p := new(Proxy)
p.Options = options.NewOptions(opts...)
p.Options.Init(options.WithString("mucp"))
// get endpoint
ep, ok := p.Options.Values().Get("proxy.endpoint")
if ok {
p.Endpoint = ep.(string)
}
// get client
c, ok := p.Options.Values().Get("proxy.client")
if ok {
p.Client = c.(client.Client)
}
// get router
r, ok := p.Options.Values().Get("proxy.router")
if ok {
p.Router = r.(router.Router)
// TODO: should we advertise?
go p.Router.Advertise()
}
return p
}