forked from dask/dask-gateway
/
main.go
589 lines (506 loc) · 12.8 KB
/
main.go
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package main
import (
"bufio"
"context"
"encoding/json"
"errors"
"flag"
"fmt"
"io"
"net"
"net/http"
"net/http/httputil"
"net/url"
"os"
"strconv"
"strings"
"sync"
"time"
)
type RoutesMsg struct {
Routes []Route
Id uint64
}
type EventsMsg struct {
Events []Event
}
type Event struct {
Id uint64
Type string
Route Route
}
type Route struct {
Kind string `json:"kind"`
SNI string `json:"sni,omitempty"`
Path string `json:"path,omitempty"`
Target string `json:"target"`
targetURL *url.URL
}
func (r *Route) String() string {
return fmt.Sprintf(
"{kind: %q, sni: %q, path: %q, target: %q}",
r.Kind, r.SNI, r.Path, r.Target,
)
}
var errMissingTarget = errors.New("Must specify `target`")
var errMissingSNI = errors.New("Must specify `sni`")
var errMissingPath = errors.New("Must specify `path`")
var errUnknownKind = errors.New("Unknown route kind")
var errInvalidScheme = errors.New("Scheme must be `http` or `https`")
func (r *Route) Validate(full bool) error {
if r.Kind == "SNI" {
if r.SNI == "" {
return errMissingSNI
}
} else if r.Kind == "PATH" {
if r.Path == "" {
return errMissingPath
}
} else {
return errUnknownKind
}
if full {
if r.Target == "" {
return errMissingTarget
}
if r.Kind == "SNI" {
r.Target = strings.TrimPrefix(r.Target, "tls://")
} else {
targetURL, err := url.Parse(r.Target)
if err != nil {
return err
}
if targetURL.Scheme != "http" && targetURL.Scheme != "https" {
return errInvalidScheme
}
r.targetURL = targetURL
}
}
return nil
}
type Proxy struct {
logger *Logger
sniRoutes map[string]string
router *Router
routesLock sync.RWMutex
proxy *httputil.ReverseProxy
}
func NewProxy(logLevel LogLevel) *Proxy {
out := Proxy{
logger: NewLogger("Proxy", logLevel),
sniRoutes: make(map[string]string),
router: NewRouter(),
}
out.proxy = &httputil.ReverseProxy{
Director: out.director,
FlushInterval: 250 * time.Millisecond,
ErrorHandler: out.errorHandler,
}
return &out
}
func awaitShutdown() {
buf := make([]byte, 10)
for {
_, err := os.Stdin.Read(buf)
if err == io.EOF {
os.Exit(0)
}
}
}
func (p *Proxy) run(address, tcpAddress, apiURL, apiToken, tlsCert, tlsKey string, isChildProcess bool) {
if isChildProcess {
go awaitShutdown()
}
if tcpAddress == "" {
tcpAddress = address
}
tlsListener, err := net.Listen("tcp", tcpAddress)
if err != nil {
p.logger.Errorf("%s", err)
os.Exit(1)
}
p.logger.Infof("TCP Proxy serving at %s", tcpAddress)
var httpListener net.Listener
var forwarder *Forwarder = nil
if address == tcpAddress {
forwarder = newForwarder(tlsListener)
httpListener = forwarder
} else {
httpListener, err = net.Listen("tcp", address)
if err != nil {
p.logger.Errorf("%s", err)
os.Exit(1)
}
}
p.logger.Infof("HTTP Proxy serving at %s", address)
go p.runHTTP(httpListener, tlsCert, tlsKey)
go p.runTCP(tlsListener, forwarder)
p.watchRoutes(apiURL, apiToken, 15*time.Second)
}
func (p *Proxy) clearRoutes() {
p.logger.Infof("Resetting routing table")
p.sniRoutes = make(map[string]string)
p.router = NewRouter()
}
func (p *Proxy) putRoute(route *Route) {
if err := route.Validate(true); err != nil {
p.logger.Warnf("Invalid route %s: %s", route, err)
return
}
p.logger.Infof("Adding route %s", route)
if route.Kind == "SNI" {
p.sniRoutes[route.SNI] = route.Target
} else {
p.router.Put(route.Path, route.targetURL)
}
}
func (p *Proxy) deleteRoute(route *Route) {
if err := route.Validate(false); err != nil {
p.logger.Warnf("Invalid route %s: %s", route, err)
return
}
p.logger.Infof("Removing route %s", route)
if route.Kind == "SNI" {
delete(p.sniRoutes, route.SNI)
} else {
p.router.Delete(route.Path)
}
}
func (p *Proxy) UpdateFromRoutes(routes []Route) {
p.routesLock.Lock()
defer p.routesLock.Unlock()
p.clearRoutes()
for _, route := range routes {
p.putRoute(&route)
}
return
}
func (p *Proxy) UpdateFromEvents(events []Event) {
p.routesLock.Lock()
defer p.routesLock.Unlock()
for _, event := range events {
if event.Type == "PUT" {
p.putRoute(&event.Route)
} else if event.Type == "DELETE" {
p.deleteRoute(&event.Route)
} else {
p.logger.Warnf("Unknown event type %s", event.Type)
}
}
}
// Tracker implementation
type apiClient struct {
client *http.Client
apiURL string
apiToken string
}
func NewApiClient(apiURL string, apiToken string) *apiClient {
return &apiClient{
client: &http.Client{
Timeout: 60 * time.Second,
},
apiURL: apiURL,
apiToken: apiToken,
}
}
func (c *apiClient) getRoutingTable() (*RoutesMsg, error) {
req, err := http.NewRequest("GET", c.apiURL, nil)
if err != nil {
return nil, err
}
req.Header.Set("Accept", "application/json")
req.Header.Set("Authorization", "token "+c.apiToken)
resp, err := c.client.Do(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
if resp.StatusCode >= 400 {
return nil, errors.New(resp.Status)
}
var msg RoutesMsg
err = json.NewDecoder(resp.Body).Decode(&msg)
return &msg, err
}
type evIter struct {
body io.ReadCloser
scanner *bufio.Scanner
events []Event
err error
}
func NewEvIter(body io.ReadCloser) *evIter {
return &evIter{
body: body,
scanner: bufio.NewScanner(body),
}
}
func (it *evIter) Next() bool {
if ok := it.scanner.Scan(); !ok {
it.body.Close()
return false
}
var msg EventsMsg
if err := json.Unmarshal(it.scanner.Bytes(), &msg); err != nil {
it.err = err
it.body.Close()
return false
}
it.events = msg.Events
return true
}
func (it *evIter) Err() error {
return it.err
}
func (it *evIter) Events() []Event {
return it.events
}
var errTooOld = errors.New("Routes `last_id` is too old, retry")
func (c *apiClient) watchRoutingEvents(lastId uint64) (*evIter, error) {
url := c.apiURL + "?watch=1&last_id=" + strconv.FormatUint(lastId, 10)
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return nil, err
}
req.Header.Set("Accept", "application/json")
req.Header.Set("Authorization", "token "+c.apiToken)
resp, err := c.client.Do(req)
if err != nil {
return nil, err
}
if resp.StatusCode >= 400 {
resp.Body.Close()
if resp.StatusCode == 410 {
return nil, errTooOld
}
return nil, errors.New(resp.Status)
}
return NewEvIter(resp.Body), nil
}
func (p *Proxy) watchRoutes(apiURL, apiToken string, maxBackoff time.Duration) {
p.logger.Infof("Watching %s for routing table updates...", apiURL)
initialBackoff := 500 * time.Millisecond
backoff := initialBackoff
doBackoff := func(msg string, err error) {
p.logger.Warnf(msg, backoff.Seconds(), err)
time.Sleep(backoff)
backoff = backoff * 2
if backoff > maxBackoff {
backoff = maxBackoff
}
}
resetBackoff := func() {
backoff = initialBackoff
}
client := NewApiClient(apiURL, apiToken)
for {
msg, err := client.getRoutingTable()
if err != nil {
doBackoff("Unexpected failure fetching routing table, retrying in %.1fs: %s", err)
continue
}
resetBackoff()
p.UpdateFromRoutes(msg.Routes)
last_id := msg.Id
for {
it, err := client.watchRoutingEvents(last_id)
if err == errTooOld {
p.logger.Debugf("last_id is too old, fetching whole routing table")
break
} else if err != nil {
doBackoff("Unexpected failure fetching routing events, retrying in %.1fs: %s", err)
break
}
for it.Next() {
events := it.Events()
if len(events) > 0 {
p.UpdateFromEvents(events)
last_id = events[len(events)-1].Id
}
}
if err := it.Err(); err != nil {
doBackoff("Unexpected failure streaming routing events, retrying in %.1fs: %s", err)
break
}
}
}
}
// HTTP Proxy Implementation
func (p *Proxy) errorHandler(w http.ResponseWriter, r *http.Request, err error) {
if err != context.Canceled {
p.logger.Warnf("Web Proxy Error: %s", err)
}
w.WriteHeader(http.StatusBadGateway)
}
func (p *Proxy) ServeHTTP(w http.ResponseWriter, req *http.Request) {
p.routesLock.RLock()
target, path := p.router.Match(req.URL.Path)
p.routesLock.RUnlock()
var uri string
if p.logger.level >= DEBUG {
uri = req.URL.RequestURI()
}
if target != nil {
targetQuery := target.RawQuery
req.URL.Scheme = target.Scheme
req.URL.Host = target.Host
req.Host = target.Host
req.URL.Path = singleJoiningSlash(target.Path, path)
if targetQuery == "" || req.URL.RawQuery == "" {
req.URL.RawQuery = targetQuery + req.URL.RawQuery
} else {
req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
}
p.logger.Infof("%s -> %s", uri, req.URL)
p.proxy.ServeHTTP(w, req)
} else {
p.logger.Infof("%s not found", uri)
http.Error(w, "Not Found", http.StatusNotFound)
}
}
func singleJoiningSlash(a, b string) string {
aslash := strings.HasSuffix(a, "/")
bslash := strings.HasPrefix(b, "/")
switch {
case aslash && bslash:
return a + b[1:]
case !aslash && !bslash:
return a + "/" + b
}
return a + b
}
func (p *Proxy) director(req *http.Request) {
// Request URL already modified above in ServeHTTP
if _, ok := req.Header["User-Agent"]; !ok {
// explicitly disable User-Agent so it's not set to default value
req.Header.Set("User-Agent", "")
}
}
func (p *Proxy) runHTTP(ln net.Listener, tlsCert, tlsKey string) {
server := &http.Server{
Handler: p,
}
var err error
if tlsCert == "" {
err = server.Serve(ln)
} else {
err = server.ServeTLS(ln, tlsCert, tlsKey)
}
if err != nil && err != http.ErrServerClosed {
p.logger.Errorf("%s", err)
os.Exit(1)
}
}
// TCP proxy implementation
type Forwarder struct {
net.Listener
conns chan net.Conn
}
func newForwarder(ln net.Listener) *Forwarder {
return &Forwarder{
Listener: ln,
conns: make(chan net.Conn),
}
}
func (h *Forwarder) Forward(conn net.Conn) {
h.conns <- conn
}
func (h *Forwarder) Accept() (net.Conn, error) {
conn := <-h.conns
return conn, nil
}
func (p *Proxy) handleConnection(inConn *net.TCPConn, forwarder *Forwarder) {
var err error
sni, isTLS, pInConn, err := readSNI(inConn)
if err != nil {
p.logger.Debugf("Error extracting SNI: %s", err)
inConn.Close()
return
}
const sniPrefix = "daskgateway-"
if !isTLS || !strings.HasPrefix(sni, sniPrefix) {
if forwarder != nil {
forwarder.Forward(pInConn)
return
} else {
p.logger.Debug("Invalid connection attempt, closing")
inConn.Close()
return
}
}
sni = sni[len(sniPrefix):]
defer inConn.Close()
p.routesLock.RLock()
outAddr := p.sniRoutes[sni]
p.routesLock.RUnlock()
if outAddr == "" {
p.logger.Infof("SNI %q not found", sni)
return
}
p.logger.Infof("SNI %q -> %q", sni, outAddr)
outConn, err := net.DialTimeout("tcp", outAddr, 10*time.Second)
if err != nil {
p.logger.Debugf("Failed to connect to destination %q: %s", outAddr, err)
return
}
defer outConn.Close()
var wg sync.WaitGroup
wg.Add(2)
go p.proxyConnections(&wg, pInConn, outConn.(*net.TCPConn))
go p.proxyConnections(&wg, outConn.(*net.TCPConn), pInConn)
wg.Wait()
}
func (p *Proxy) proxyConnections(wg *sync.WaitGroup, in, out tcpConn) {
defer wg.Done()
if _, err := io.Copy(in, out); err != nil {
p.logger.Debugf("Error proxying %q -> %q: %s", in.RemoteAddr(), out.RemoteAddr(), err)
}
in.CloseRead()
out.CloseWrite()
}
func (p *Proxy) runTCP(ln net.Listener, forwarder *Forwarder) {
for {
c, err := ln.Accept()
if err != nil {
p.logger.Debugf("Failed to accept new connection: %s", err)
}
go p.handleConnection(c.(*net.TCPConn), forwarder)
}
}
func main() {
var (
address string
tcpAddress string
apiURL string
logLevelString string
isChildProcess bool
tlsCert string
tlsKey string
)
command := flag.NewFlagSet("dask-gateway-proxy", flag.ExitOnError)
command.StringVar(&address, "address", ":8000", "HTTP proxy listening address")
command.StringVar(&tcpAddress, "tcp-address", "", "TCP proxy listening address. If empty, `address` will be used.")
command.StringVar(&apiURL, "api-url", "", "The URL the proxy should watch for updating the routing table")
command.StringVar(&logLevelString, "log-level", "INFO",
"The log level. One of {DEBUG, INFO, WARN, ERROR}")
command.BoolVar(&isChildProcess, "is-child-process", false,
"If set, will exit when stdin EOFs. Useful when running as a child process.")
command.StringVar(&tlsCert, "tls-cert", "", "TLS cert to use, if any.")
command.StringVar(&tlsKey, "tls-key", "", "TLS key to use, if any.")
command.Parse(os.Args[1:])
token := os.Getenv("DASK_GATEWAY_PROXY_TOKEN")
if token == "" {
panic("DASK_GATEWAY_PROXY_TOKEN environment variable not set")
}
logLevel := ParseLevel(logLevelString)
if (tlsCert == "") != (tlsKey == "") {
panic("Both -tls-cert and -tls-key must be set to use HTTPS")
}
if apiURL == "" {
panic("-api-url must be set")
}
if _, err := url.Parse(apiURL); err != nil {
panic("Invalid -api-url: " + err.Error())
}
proxy := NewProxy(logLevel)
proxy.run(address, tcpAddress, apiURL, token, tlsCert, tlsKey, isChildProcess)
}