micro/proxy/http/http.go

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// Package http provides a micro rpc to http proxy
package http
import (
"bytes"
"context"
"io"
"io/ioutil"
"net/http"
"net/url"
"path"
"github.com/unistack-org/micro/v3/errors"
"github.com/unistack-org/micro/v3/proxy"
"github.com/unistack-org/micro/v3/server"
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)
// Proxy will proxy rpc requests as http POST requests. It is a server.Proxy
type Proxy struct {
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options proxy.Options
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// The http backend to call
Endpoint string
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// first request
first bool
}
func getMethod(hdr map[string]string) string {
switch hdr["Micro-Method"] {
case "GET", "HEAD", "POST", "PUT", "DELETE", "CONNECT", "OPTIONS", "TRACE", "PATCH":
return hdr["Micro-Method"]
default:
return "POST"
}
}
func getEndpoint(hdr map[string]string) string {
ep := hdr["Micro-Endpoint"]
if len(ep) > 0 && ep[0] == '/' {
return ep
}
return ""
}
func getTopic(hdr map[string]string) string {
ep := hdr["Micro-Topic"]
if len(ep) > 0 && ep[0] == '/' {
return ep
}
return "/" + hdr["Micro-Topic"]
}
// ProcessMessage handles incoming asynchronous messages
func (p *Proxy) ProcessMessage(ctx context.Context, msg server.Message) error {
if p.Endpoint == "" {
p.Endpoint = proxy.DefaultEndpoint
}
// get the header
hdr := msg.Header()
// get topic
// use /topic as endpoint
endpoint := getTopic(hdr)
// set the endpoint
if len(endpoint) == 0 {
endpoint = p.Endpoint
} else {
// add endpoint to backend
u, err := url.Parse(p.Endpoint)
if err != nil {
return errors.InternalServerError(msg.Topic(), err.Error())
}
u.Path = path.Join(u.Path, endpoint)
endpoint = u.String()
}
// send to backend
hreq, err := http.NewRequest("POST", endpoint, bytes.NewReader(msg.Body()))
if err != nil {
return errors.InternalServerError(msg.Topic(), err.Error())
}
// set the headers
for k, v := range hdr {
hreq.Header.Set(k, v)
}
// make the call
hrsp, err := http.DefaultClient.Do(hreq)
if err != nil {
return errors.InternalServerError(msg.Topic(), err.Error())
}
// read body
b, err := ioutil.ReadAll(hrsp.Body)
hrsp.Body.Close()
if err != nil {
return errors.InternalServerError(msg.Topic(), err.Error())
}
if hrsp.StatusCode != 200 {
return errors.New(msg.Topic(), string(b), int32(hrsp.StatusCode))
}
return nil
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}
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// ServeRequest honours the server.Router interface
func (p *Proxy) ServeRequest(ctx context.Context, req server.Request, rsp server.Response) error {
if p.Endpoint == "" {
p.Endpoint = proxy.DefaultEndpoint
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}
for {
// get data
body, err := req.Read()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
// get the header
hdr := req.Header()
// get method
method := getMethod(hdr)
// get endpoint
endpoint := getEndpoint(hdr)
// set the endpoint
if len(endpoint) == 0 {
endpoint = p.Endpoint
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} else {
// add endpoint to backend
u, err := url.Parse(p.Endpoint)
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if err != nil {
return errors.InternalServerError(req.Service(), err.Error())
}
u.Path = path.Join(u.Path, endpoint)
endpoint = u.String()
}
// send to backend
hreq, err := http.NewRequest(method, endpoint, bytes.NewReader(body))
if err != nil {
return errors.InternalServerError(req.Service(), err.Error())
}
// set the headers
for k, v := range hdr {
hreq.Header.Set(k, v)
}
// make the call
hrsp, err := http.DefaultClient.Do(hreq)
if err != nil {
return errors.InternalServerError(req.Service(), err.Error())
}
// read body
b, err := ioutil.ReadAll(hrsp.Body)
hrsp.Body.Close()
if err != nil {
return errors.InternalServerError(req.Service(), err.Error())
}
// set response headers
hdr = map[string]string{}
for k := range hrsp.Header {
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hdr[k] = hrsp.Header.Get(k)
}
// write the header
rsp.WriteHeader(hdr)
// write the body
err = rsp.Write(b)
if err == io.EOF {
return nil
}
if err != nil {
return errors.InternalServerError(req.Service(), err.Error())
}
}
}
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func (p *Proxy) String() string {
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return "http"
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}
// NewSingleHostProxy returns a router which sends requests to a single http backend
func NewSingleHostProxy(url string) proxy.Proxy {
return &Proxy{
Endpoint: url,
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}
}
// NewProxy returns a new proxy which will route using a http client
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func NewProxy(opts ...proxy.Option) proxy.Proxy {
var options proxy.Options
for _, o := range opts {
o(&options)
}
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p := new(Proxy)
p.Endpoint = options.Endpoint
p.options = options
return p
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}