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apiserver.go
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apiserver.go
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// Package apiserver provides a HTTP gateway for invoking Lever methods without
// the use of a gRPC client.
package apiserver
import (
"bufio"
"encoding/json"
"fmt"
"io"
"net/http"
"net/url"
"strings"
"sync"
leverapi "github.com/leveros/leveros/api"
"github.com/leveros/leveros/config"
"github.com/leveros/leveros/core"
"github.com/leveros/leveros/host"
"github.com/leveros/leveros/leverutil"
)
// PackageName is the name of this package.
const PackageName = "apiserver"
var (
// ListenPortFlag is the port the API server should listen on.
ListenPortFlag = config.DeclareString(PackageName, "listenPort", "3503")
// DisableAPIServerFlag disables the creation of an HTTP API server.
DisableAPIServerFlag = config.DeclareBool(PackageName, "disableAPIServer")
)
var logger = leverutil.GetLogger(PackageName, "Server")
const maxNonChanRequestSize = 512 * 1024 // 512 KiB
var bufferedReaderPool = &sync.Pool{
New: func() interface{} {
return bufio.NewReaderSize(nil, maxNonChanRequestSize)
},
}
var bufferPool = &sync.Pool{
New: func() interface{} {
return make([]byte, maxNonChanRequestSize)
},
}
// Server is an HTTP API server that acts as a gateway to Lever services for
// non-gRPC clients.
type Server struct {
httpServer *http.Server
leverClient *leverapi.Client
}
// NewServer returns a new instance of Server.
func NewServer() (server *Server, err error) {
if DisableAPIServerFlag.Get() {
return nil, nil
}
server = new(Server)
server.leverClient, err = leverapi.NewClient()
if err != nil {
return nil, err
}
// Pipe Lever calls into own host listener.
server.leverClient.ForceHost =
"127.0.0.1:" + host.EnvExtListenPortFlag.Get()
server.httpServer = &http.Server{
Addr: ":" + ListenPortFlag.Get(),
Handler: server,
}
go server.listenAndServe()
return server, nil
}
func (server *Server) listenAndServe() {
err := server.httpServer.ListenAndServe()
if err != nil {
logger.WithFields("err", err).Error("Listen and server error")
}
}
// ServeHTTP serves individual HTTP requests.
func (server *Server) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
origin := req.Header.Get("Origin")
if origin != "" {
// TODO: Perhaps a lever.json config param could restrict origin
// to prevent CSRF.
resp.Header().Set("Access-Control-Allow-Origin", origin)
resp.Header().Set(
"Access-Control-Allow-Headers",
"Accept, Content-Type, Content-Length, Accept-Encoding, "+
"X-CSRF-Token, Authorization")
}
if req.Method == "OPTIONS" {
resp.Header().Set("Access-Control-Allow-Methods", "POST, OPTIONS")
resp.WriteHeader(http.StatusOK)
return
}
if req.Method != "POST" {
resp.WriteHeader(http.StatusMethodNotAllowed)
return
}
leverURLStr := fmt.Sprintf("lever://%s%s", req.Host, req.URL.Path)
leverURL, err := core.ParseLeverURL(leverURLStr)
if err != nil {
logger.WithFields("err", err).Debug("Error parsing Lever URL")
resp.WriteHeader(http.StatusBadRequest)
return
}
queryValues, err := url.ParseQuery(req.URL.RawQuery)
if err != nil {
logger.WithFields("err", err).Debug("Error parsing URL query")
resp.WriteHeader(http.StatusBadRequest)
return
}
forceEnv := queryValues.Get("forceenv")
if forceEnv != "" {
leverURL.Environment = forceEnv
}
leverURLStr = leverURL.String()
reader := bufferedReaderPool.Get().(*bufio.Reader)
reader.Reset(req.Body)
defer bufferedReaderPool.Put(reader)
defer req.Body.Close()
if leverapi.IsChanMethod(leverURL.Method) {
// TODO: Byte args not supported. Any way to support that?
// How to delimit args from rest?
done := false
var line []byte
line, err = reader.ReadBytes('\n')
if err != nil {
if err == io.EOF {
done = true
} else {
logger.WithFields("err", err).Error("Read error")
return
}
}
if len(line) == 0 {
resp.WriteHeader(http.StatusBadRequest)
return
}
var args []interface{}
err = json.Unmarshal(line, &args)
if err != nil {
resp.WriteHeader(http.StatusBadRequest)
logger.WithFields("err", err).Debug("Malformed JSON")
return
}
var stream leverapi.Stream
stream, err = server.leverClient.InvokeChanURL(leverURLStr, args...)
if err != nil {
resp.WriteHeader(http.StatusInternalServerError)
logger.WithFields("err", err).Error("InvokeChanURL error")
return
}
errCh := make(chan bool)
workerDoneCh := make(chan struct{})
go replyStreamWorker(stream, resp, errCh, workerDoneCh)
if req.Header.Get("Content-Type") == "application/json" {
for !done {
line, err = reader.ReadBytes('\n')
if err != nil {
if err == io.EOF {
done = true
} else {
logger.WithFields("err", err).Error("Read error")
errCh <- true
<-workerDoneCh
return
}
}
if len(line) > 0 {
var msg interface{}
err = json.Unmarshal(line, &msg)
if err != nil {
logger.WithFields("err", err).Debug("Malformed JSON")
errCh <- true
<-workerDoneCh
return
}
stream.Send(msg)
}
}
} else {
for !done {
buffer := bufferPool.Get().([]byte)
defer bufferPool.Put(buffer)
var size int
size, err = reader.Read(buffer)
if err != nil {
if err == io.EOF {
done = true
}
logger.WithFields("err", err).Error("Read error")
errCh <- true
<-workerDoneCh
return
}
msg := buffer[:size]
stream.Send(msg)
}
}
err = stream.Close()
if err != nil {
logger.WithFields("err", err).Debug(
"Stream close error")
errCh <- true
<-workerDoneCh
return
}
errCh <- false
<-workerDoneCh
} else {
buffer := bufferPool.Get().([]byte)
defer bufferPool.Put(buffer)
var size int
size, err = io.ReadFull(reader, buffer)
if err != nil {
if err != io.EOF && err != io.ErrUnexpectedEOF {
logger.WithFields("err", err).Error("Read error")
return
}
}
if size == maxNonChanRequestSize &&
err != io.EOF &&
err != io.ErrUnexpectedEOF {
resp.WriteHeader(http.StatusBadRequest)
_, err = resp.Write([]byte("\"Exceeded maximum request size\""))
if err != nil {
logger.WithFields("err", err).Debug("Write error")
}
return
}
var args []interface{}
contentType := req.Header.Get("Content-Type")
contentTypeSplit := strings.Split(contentType, ";")
switch contentTypeSplit[0] {
case "application/json":
err = json.Unmarshal(buffer[:size], &args)
if err != nil {
resp.WriteHeader(http.StatusBadRequest)
logger.WithFields("err", err).Debug("JSON unmarshal error")
return
}
case "application/x-www-form-urlencoded":
// TODO
resp.WriteHeader(http.StatusBadRequest)
logger.WithFields("contentType", contentType).Error(
"Content type not yet supported")
return
default:
args = make([]interface{}, 1)
args[0] = buffer[:size]
}
var reply interface{}
err = server.leverClient.InvokeURL(&reply, leverURLStr, args...)
if err != nil {
resp.WriteHeader(http.StatusInternalServerError)
remoteErr, ok := err.(*leverapi.RemoteError)
if ok {
reply = remoteErr.Err
} else {
remoteByteErr, ok := err.(*leverapi.RemoteByteError)
if ok {
reply = remoteByteErr.Err
} else {
logger.WithFields("err", err).Error("Internal Lever error")
return
}
}
} else {
resp.WriteHeader(http.StatusOK)
}
err = writeReply(resp, reply)
if err != nil {
logger.WithFields("err", err).Error("Writing reply failed")
return
}
}
}
func replyStreamWorker(
stream leverapi.Stream, resp http.ResponseWriter, errCh chan bool,
workerDoneCh chan struct{}) {
isFirst := true
defer close(workerDoneCh)
receiveCh := make(chan interface{})
receiveErrCh := make(chan error)
go streamReceiveWorker(stream, receiveCh, receiveErrCh)
for {
select {
case msg := <-receiveCh:
if isFirst {
resp.WriteHeader(http.StatusOK)
isFirst = false
}
byteMsg, isByte := msg.([]byte)
if isByte {
if isFirst {
resp.Header().Set("Content-Type", "application/json")
}
_, err := resp.Write(byteMsg)
if err != nil {
logger.WithFields("err", err).Debug("Write error")
return
}
} else {
if isFirst {
resp.Header().Set(
"Content-Type", "application/octet-stream")
}
var err error
byteMsg, err = json.Marshal(msg)
if err != nil {
logger.WithFields("err", err).Error("JSON marshal error")
return
}
_, err = resp.Write(byteMsg)
if err != nil {
logger.WithFields("err", err).Debug("Write error")
return
}
}
case err := <-receiveErrCh:
if err == io.EOF {
if isFirst {
resp.WriteHeader(http.StatusOK)
}
return
}
if isFirst {
resp.WriteHeader(http.StatusInternalServerError)
}
var byteErr []byte
remoteErr, ok := err.(*leverapi.RemoteError)
if ok {
if isFirst {
resp.Header().Set("Content-Type", "application/json")
}
byteErr, err = json.Marshal(remoteErr.Err)
if err != nil {
logger.WithFields("err", err).Error("JSON marshal error")
return
}
} else {
remoteByteErr, ok := err.(*leverapi.RemoteByteError)
if ok {
if isFirst {
resp.Header().Set(
"Content-Type", "application/octet-stream")
}
byteErr = remoteByteErr.Err
} else {
logger.WithFields("err", err).Error("Internal Lever error")
return
}
}
_, err = resp.Write(byteErr)
if err != nil {
logger.WithFields("err", err).Debug("Write error")
return
}
case isErr := <-errCh:
if isErr && isFirst {
resp.WriteHeader(http.StatusInternalServerError)
}
return
}
isFirst = false
}
}
func streamReceiveWorker(
stream leverapi.Stream, receiveCh chan interface{},
receiveErrCh chan error) {
for {
var msg interface{}
err := stream.Receive(&msg)
if err != nil {
receiveErrCh <- err
return
}
receiveCh <- msg
}
}
func writeReply(resp http.ResponseWriter, reply interface{}) (err error) {
bytes, isByte := reply.([]byte)
if !isByte {
resp.Header().Set("Content-Type", "application/json")
bytes, err = json.Marshal(reply)
if err != nil {
return err
}
} else {
resp.Header().Set("Content-Type", "application/octet-stream")
}
_, err = resp.Write(bytes)
if err != nil {
return err
}
return nil
}