micro/proxy/mucp/mucp.go
2020-03-26 08:05:00 +00:00

634 lines
15 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/v2/client"
"github.com/micro/go-micro/v2/client/selector"
"github.com/micro/go-micro/v2/codec"
"github.com/micro/go-micro/v2/codec/bytes"
"github.com/micro/go-micro/v2/errors"
"github.com/micro/go-micro/v2/logger"
"github.com/micro/go-micro/v2/metadata"
"github.com/micro/go-micro/v2/proxy"
"github.com/micro/go-micro/v2/router"
"github.com/micro/go-micro/v2/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 proxy.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
}
// 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 {
nodes := make([]string, 0, len(routes))
for _, node := range routes {
address := node.Address
if len(node.Gateway) > 0 {
address = node.Gateway
}
nodes = append(nodes, address)
}
return nodes
}
func toSlice(r map[uint64]router.Route) []router.Route {
routes := make([]router.Route, 0, len(r))
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
}
func (p *Proxy) filterRoutes(ctx context.Context, routes []router.Route) []router.Route {
md, ok := metadata.FromContext(ctx)
if !ok {
return routes
}
//nolint:prealloc
var filteredRoutes []router.Route
// filter the routes based on our headers
for _, route := range routes {
// process only routes for this id
if id := md["Micro-Router"]; len(id) > 0 {
if route.Router != id {
// skip routes that don't mwatch
continue
}
}
// only process routes with this network
if net := md["Micro-Network"]; len(net) > 0 {
if route.Network != net {
// skip routes that don't mwatch
continue
}
}
// process only this gateway
if gw := md["Micro-Gateway"]; len(gw) > 0 {
// if the gateway matches our address
// special case, take the routes with no gateway
// TODO: should we strip the gateway from the context?
if gw == p.Router.Options().Address {
if len(route.Gateway) > 0 && route.Gateway != gw {
continue
}
// otherwise its a local route and we're keeping it
} else {
// gateway does not match our own
if route.Gateway != gw {
continue
}
}
}
// TODO: address based filtering
// address := md["Micro-Address"]
// TODO: label based filtering
// requires new field in routing table : route.Labels
// passed the filter checks
filteredRoutes = append(filteredRoutes, route)
}
if logger.V(logger.TraceLevel, logger.DefaultLogger) {
logger.Tracef("Proxy filtered routes %+v", filteredRoutes)
}
return filteredRoutes
}
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(ctx context.Context, service string) ([]router.Route, error) {
// lookup the route cache first
p.Lock()
cached, ok := p.Routes[service]
if ok {
p.Unlock()
routes := toSlice(cached)
return p.filterRoutes(ctx, routes), nil
}
p.Unlock()
// cache routes for the service
routes, err := p.cacheRoutes(service)
if err != nil {
return nil, err
}
return p.filterRoutes(ctx, routes), nil
}
func (p *Proxy) cacheRoutes(service string) ([]router.Route, error) {
// lookup the routes in the router
results, err := p.Router.Lookup(router.QueryService(service))
if err != nil {
// assumption that we're ok with stale routes
// otherwise return the error
return nil, err
}
// update the proxy cache
p.Lock()
// delete the existing reference to the service
delete(p.Routes, service)
for _, route := range results {
// create if does not exist
if _, ok := p.Routes[service]; !ok {
p.Routes[service] = make(map[uint64]router.Route)
}
// cache the route based on its unique hash
p.Routes[service][route.Hash()] = route
}
// make a copy of the service routes
routes := p.Routes[service]
p.Unlock()
// return routes to the caller
return toSlice(routes), nil
}
// refreshMetrics will refresh any metrics for our local cached routes.
// we may not receive new watch events for these as they change.
func (p *Proxy) refreshMetrics() {
// get a list of services to update
p.RLock()
services := make([]string, 0, len(p.Routes))
for service := range p.Routes {
services = append(services, service)
}
p.RUnlock()
// get and cache the routes for the service
for _, service := range services {
p.cacheRoutes(service)
}
}
// manageRoutes applies action on a given route to Proxy route cache
func (p *Proxy) manageRoutes(route router.Route, action string) error {
// we only cache what we are actually concerned with
p.Lock()
defer p.Unlock()
if logger.V(logger.TraceLevel, logger.DefaultLogger) {
logger.Tracef("Proxy taking route action %v %+v\n", action, route)
}
switch action {
case "create", "update":
if _, ok := p.Routes[route.Service]; !ok {
return fmt.Errorf("not called %s", route.Service)
}
p.Routes[route.Service][route.Hash()] = route
case "delete":
// delete that specific route
delete(p.Routes[route.Service], route.Hash())
// clean up the cache entirely
if len(p.Routes[route.Service]) == 0 {
delete(p.Routes, route.Service)
}
default:
return fmt.Errorf("unknown action: %s", action)
}
return nil
}
// watchRoutes watches service routes and updates proxy cache
func (p *Proxy) watchRoutes() {
// route watcher
w, err := p.Router.Watch()
if err != nil {
return
}
defer w.Stop()
for {
event, err := w.Next()
if err != nil {
return
}
if err := p.manageRoutes(event.Route, event.Type.String()); err != nil {
// TODO: should we bail here?
continue
}
}
}
// ProcessMessage acts as a message exchange and forwards messages to ongoing topics
// TODO: should we look at p.Endpoint and only send to the local endpoint? probably
func (p *Proxy) ProcessMessage(ctx context.Context, msg server.Message) error {
// TODO: check that we're not broadcast storming by sending to the same topic
// that we're actually subscribed to
if logger.V(logger.TraceLevel, logger.DefaultLogger) {
logger.Tracef("Proxy received message for %s", msg.Topic())
}
var errors []string
// directly publish to the local client
if err := p.Client.Publish(ctx, msg); err != nil {
errors = append(errors, err.Error())
}
// publish to all links
for _, client := range p.Links {
if err := client.Publish(ctx, msg); err != nil {
errors = append(errors, err.Error())
}
}
if len(errors) == 0 {
return nil
}
// there is no error...muahaha
return fmt.Errorf("Message processing error: %s", strings.Join(errors, "\n"))
}
// 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")
}
if logger.V(logger.TraceLevel, logger.DefaultLogger) {
logger.Tracef("Proxy received request for %s %s", service, endpoint)
}
// 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(ctx, 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(ctx, service)
if err != nil {
return err
}
routes = addr
}
//nolint:prealloc
opts := []client.CallOption{
// set strategy to round robin
client.WithSelectOption(selector.WithStrategy(selector.RoundRobin)),
}
// 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 {
opts = append(opts,
client.WithAddress(addresses...),
)
// serve the normal way
return p.serveRequest(ctx, p.Client, service, endpoint, req, rsp, opts...)
}
// 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...))
}
if logger.V(logger.TraceLevel, logger.DefaultLogger) {
logger.Tracef("Proxy calling %+v\n", addresses)
}
// serve the normal way
return p.serveRequest(ctx, p.Client, service, endpoint, req, rsp, opts...)
}
// we're assuming we need routes to operate on
if len(routes) == 0 {
return errors.InternalServerError("go.micro.proxy", "route not found")
}
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
}
if logger.V(logger.TraceLevel, logger.DefaultLogger) {
logger.Tracef("Proxy using route %+v\n", route)
}
// set the address to call
addresses := toNodes([]router.Route{route})
// set the address in the options
// disable retries since its one route processing
opts = append(opts,
client.WithAddress(addresses...),
client.WithRetries(0),
)
// do the request with the link
gerr = p.serveRequest(ctx, link, service, endpoint, req, rsp, opts...)
// 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{Data: 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()
// if we receive a grpc stream we have to refire the initial request
c, ok := req.Codec().(codec.Codec)
if ok && c.String() == "grpc" && link.String() == "grpc" {
// get the header from client
hdr := req.Header()
msg := &codec.Message{
Type: codec.Request,
Header: hdr,
Body: body,
}
// write the raw request
err = stream.Request().Codec().Write(msg, nil)
if err == io.EOF {
return nil
} else if err != nil {
return err
}
}
// create client request read loop if streaming
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
}
}
}
func (p *Proxy) String() string {
return "mucp"
}
// NewSingleHostProxy returns a proxy which sends requests to a single backend
func NewSingleHostProxy(endpoint string) *Proxy {
return &Proxy{
Endpoint: endpoint,
}
}
// NewProxy returns a new proxy which will route based on mucp headers
func NewProxy(opts ...proxy.Option) proxy.Proxy {
var options proxy.Options
for _, o := range opts {
o(&options)
}
p := new(Proxy)
p.Links = map[string]client.Client{}
p.Routes = make(map[string]map[uint64]router.Route)
p.options = options
// get endpoint
p.Endpoint = options.Endpoint
// set the client
p.Client = options.Client
// get router
p.Router = options.Router
// set the default client
if p.Client == nil {
p.Client = client.DefaultClient
}
// create default router and start it
if p.Router == nil {
p.Router = router.DefaultRouter
}
// set the links
if options.Links != nil {
// get client
p.Links = options.Links
}
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)
}
}()
go func() {
// TODO: speed up refreshing of metrics
// without this ticking effort e.g stream
t := time.NewTicker(time.Second * 10)
defer t.Stop()
// we must refresh route metrics since they do not trigger new events
for range t.C {
// refresh route metrics
p.refreshMetrics()
}
}()
return p
}