micro/proxy/mucp/mucp.go
2019-09-20 16:25:29 +01:00

457 lines
10 KiB
Go

// Package mucp transparently forwards the incoming request using a go-micro client.
package mucp
import (
"context"
"fmt"
"io"
"sort"
"strings"
"sync"
"time"
"github.com/micro/go-micro/client"
"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/errors"
"github.com/micro/go-micro/proxy"
"github.com/micro/go-micro/router"
"github.com/micro/go-micro/server"
)
// 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 specifies the fixed service endpoint to call.
Endpoint string
// The client to use for outbound requests in the local network
Client client.Client
// Links are used for outbound requests not in the local network
Links map[string]client.Client
// The router for routes
Router router.Router
// A fib of routes service:address
sync.RWMutex
Routes map[string]map[uint64]router.Route
// The channel to monitor watcher errors
errChan chan error
}
// 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
}
}
}
// toNodes returns a list of node addresses from given routes
func toNodes(routes []router.Route) []string {
var nodes []string
for _, node := range routes {
address := node.Address
if len(node.Gateway) > 0 {
address = node.Gateway
}
nodes = append(nodes, address)
}
return nodes
}
func (p *Proxy) getLink(r router.Route) (client.Client, error) {
if r.Link == "local" || len(p.Links) == 0 {
return p.Client, nil
}
l, ok := p.Links[r.Link]
if !ok {
return nil, errors.InternalServerError("go.micro.proxy", "link not found")
}
return l, nil
}
func (p *Proxy) getRoute(service string) ([]router.Route, error) {
toSlice := func(r map[uint64]router.Route) []router.Route {
var routes []router.Route
for _, v := range r {
routes = append(routes, v)
}
// sort the routes in order of metric
sort.Slice(routes, func(i, j int) bool { return routes[i].Metric < routes[j].Metric })
return routes
}
// lookup the route cache first
p.Lock()
routes, ok := p.Routes[service]
if ok {
p.Unlock()
return toSlice(routes), nil
}
p.Unlock()
// lookup the routes in the router
results, err := p.Router.Lookup(router.NewQuery(router.QueryService(service)))
if err != nil {
// check the status of the router
if status := p.Router.Status(); status.Code == router.Error {
return nil, status.Error
}
// otherwise return the error
return nil, err
}
// update the proxy cache
p.Lock()
for _, route := range results {
// create if does not exist
if _, ok := p.Routes[service]; !ok {
p.Routes[service] = make(map[uint64]router.Route)
}
p.Routes[service][route.Hash()] = route
}
routes = p.Routes[service]
p.Unlock()
return toSlice(routes), nil
}
// manageRouteCache applies action on a given route to Proxy route cache
func (p *Proxy) manageRouteCache(route router.Route, action string) error {
switch action {
case "create", "update":
if _, ok := p.Routes[route.Service]; !ok {
p.Routes[route.Service] = make(map[uint64]router.Route)
}
p.Routes[route.Service][route.Hash()] = route
case "delete":
delete(p.Routes[route.Service], route.Hash())
default:
return fmt.Errorf("unknown action: %s", action)
}
return nil
}
// watchRoutes watches service routes and updates proxy cache
func (p *Proxy) watchRoutes() {
// this is safe to do as the only way watchRoutes returns is
// when some error is written into error channel - we want to bail then
defer close(p.errChan)
// route watcher
w, err := p.Router.Watch()
if err != nil {
p.errChan <- err
return
}
for {
event, err := w.Next()
if err != nil {
p.errChan <- err
return
}
p.Lock()
if err := p.manageRouteCache(event.Route, fmt.Sprintf("%s", event.Type)); err != nil {
// TODO: should we bail here?
p.Unlock()
continue
}
p.Unlock()
}
}
func (p *Proxy) SendRequest(ctx context.Context, req client.Request, rsp client.Response) error {
return errors.InternalServerError("go.micro.proxy", "SendRequest is unsupported")
}
// ServeRequest honours the server.Router interface
func (p *Proxy) ServeRequest(ctx context.Context, req server.Request, rsp server.Response) error {
// determine if its local routing
var local bool
// address to call
var addresses []string
// routes
var routes []router.Route
// service name to call
service := req.Service()
// endpoint to call
endpoint := req.Endpoint()
if len(service) == 0 {
return errors.BadRequest("go.micro.proxy", "service name is blank")
}
// are we network routing or local routing
if len(p.Links) == 0 {
local = true
}
// 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
routes = 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
}
routes = addr
}
// if the address is already set just serve it
// TODO: figure it out if we should know to pick a link
if len(addresses) > 0 {
// serve the normal way
return p.serveRequest(ctx, p.Client, service, endpoint, req, rsp, client.WithAddress(addresses...))
}
// there's no links e.g we're local routing then just serve it with addresses
if local {
var opts []client.CallOption
// set address if available via routes or specific endpoint
if len(routes) > 0 {
addresses := toNodes(routes)
opts = append(opts, client.WithAddress(addresses...))
}
// serve the normal way
return p.serveRequest(ctx, p.Client, service, endpoint, req, rsp, opts...)
}
var gerr error
// we're routing globally with multiple links
// so we need to pick a link per route
for _, route := range routes {
// pick the link or error out
link, err := p.getLink(route)
if err != nil {
// ok let's try again
gerr = err
continue
}
// set the address to call
addresses := toNodes([]router.Route{route})
// do the request with the link
gerr = p.serveRequest(ctx, link, service, endpoint, req, rsp, client.WithAddress(addresses...))
// return on no error since we succeeded
if gerr == nil {
return nil
}
// return where the context deadline was exceeded
if gerr == context.Canceled || gerr == context.DeadlineExceeded {
return err
}
// otherwise attempt to do it all over again
}
// if we got here something went really badly wrong
return gerr
}
func (p *Proxy) serveRequest(ctx context.Context, link client.Client, service, endpoint string, req server.Request, rsp server.Response, opts ...client.CallOption) error {
// read initial request
body, err := req.Read()
if err != nil {
return err
}
// create new request with raw bytes body
creq := link.NewRequest(service, endpoint, &bytes.Frame{body}, client.WithContentType(req.ContentType()))
// not a stream so make a client.Call request
if !req.Stream() {
crsp := new(bytes.Frame)
// make a call to the backend
if err := link.Call(ctx, creq, crsp, opts...); err != nil {
return err
}
// write the response
if err := rsp.Write(crsp.Data); err != nil {
return err
}
return nil
}
// create new stream
stream, err := link.Stream(ctx, creq, opts...)
if err != nil {
return err
}
defer stream.Close()
// create client request read loop if streaming
go readLoop(req, stream)
// get raw response
resp := stream.Response()
// route watcher error
var watchErr error
// create server response write loop
for {
select {
case err := <-p.errChan:
if err != nil {
watchErr = err
}
return watchErr
default:
// 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.Links = map[string]client.Client{}
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)
}
// set the default client
if p.Client == nil {
p.Client = client.DefaultClient
}
// get client
links, ok := p.Options.Values().Get("proxy.links")
if ok {
p.Links = links.(map[string]client.Client)
}
// get router
r, ok := p.Options.Values().Get("proxy.router")
if ok {
p.Router = r.(router.Router)
}
// create default router and start it
if p.Router == nil {
p.Router = router.DefaultRouter
}
// routes cache
p.Routes = make(map[string]map[uint64]router.Route)
// watch router service routes
p.errChan = make(chan error, 1)
go func() {
// continuously attempt to watch routes
for {
// watch the routes
p.watchRoutes()
// in case of failure just wait a second
time.Sleep(time.Second)
}
}()
return p
}