micro/api/handler/http/http.go

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// Package http is a http reverse proxy handler
package http
import (
"errors"
"fmt"
"math/rand"
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"net/http"
"net/http/httputil"
"net/url"
"github.com/unistack-org/micro/v3/api"
"github.com/unistack-org/micro/v3/api/handler"
"github.com/unistack-org/micro/v3/registry"
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)
const (
Handler = "http"
)
type httpHandler struct {
options handler.Options
// set with different initializer
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s *api.Service
}
func (h *httpHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
service, err := h.getService(r)
if err != nil {
w.WriteHeader(500)
return
}
if len(service) == 0 {
w.WriteHeader(404)
return
}
rp, err := url.Parse(service)
if err != nil {
w.WriteHeader(500)
return
}
httputil.NewSingleHostReverseProxy(rp).ServeHTTP(w, r)
}
// getService returns the service for this request from the selector
func (h *httpHandler) getService(r *http.Request) (string, error) {
var service *api.Service
if h.s != nil {
// we were given the service
service = h.s
} else if h.options.Router != nil {
// try get service from router
s, err := h.options.Router.Route(r)
if err != nil {
return "", err
}
service = s
} else {
// we have no way of routing the request
return "", errors.New("no route found")
}
// get the nodes for this service
var nodes []*registry.Node
for _, srv := range service.Services {
nodes = append(nodes, srv.Nodes...)
}
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// select a random node
if len(nodes) == 0 {
return "", errors.New("no route found")
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}
node := nodes[rand.Int()%len(nodes)]
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return fmt.Sprintf("http://%s", node.Address), nil
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}
func (h *httpHandler) String() string {
return "http"
}
// NewHandler returns a http proxy handler
func NewHandler(opts ...handler.Option) handler.Handler {
options := handler.NewOptions(opts...)
return &httpHandler{
options: options,
}
}
// WithService creates a handler with a service
func WithService(s *api.Service, opts ...handler.Option) handler.Handler {
options := handler.NewOptions(opts...)
return &httpHandler{
options: options,
s: s,
}
}