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bundle.go
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bundle.go
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// Copyright 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package apiGatewayDeploy
import (
"crypto/md5"
"crypto/sha256"
"crypto/sha512"
"encoding/base64"
"encoding/hex"
"errors"
"fmt"
"hash"
"hash/crc32"
"io"
"io/ioutil"
"net/http"
"net/url"
"os"
"path"
"strings"
"time"
)
var (
markDeploymentFailedAfter time.Duration
bundleDownloadConnTimeout time.Duration
bundleRetryDelay = time.Second
downloadQueue = make(chan *DownloadRequest, downloadQueueSize)
workerQueue = make(chan chan *DownloadRequest, concurrentDownloads)
)
// simple doubling back-off
func createBackoff(retryIn, maxBackOff time.Duration) func() {
return func() {
log.Debugf("backoff called. will retry in %s.", retryIn)
time.Sleep(retryIn)
retryIn = retryIn * time.Duration(2)
if retryIn > maxBackOff {
retryIn = maxBackOff
}
}
}
func queueDownloadRequest(dep DataDeployment) {
hashWriter, err := getHashWriter(dep.BundleChecksumType)
if err != nil {
msg := fmt.Sprintf("invalid bundle checksum type: %s for deployment: %s", dep.BundleChecksumType, dep.ID)
log.Error(msg)
setDeploymentResults(apiDeploymentResults{
{
ID: dep.ID,
Status: RESPONSE_STATUS_FAIL,
ErrorCode: TRACKER_ERR_BUNDLE_BAD_CHECKSUM,
Message: msg,
},
})
return
}
retryIn := bundleRetryDelay
maxBackOff := 5 * time.Minute
markFailedAt := time.Now().Add(markDeploymentFailedAfter)
req := &DownloadRequest{
dep: dep,
hashWriter: hashWriter,
bundleFile: getBundleFile(dep),
backoffFunc: createBackoff(retryIn, maxBackOff),
markFailedAt: markFailedAt,
}
downloadQueue <- req
}
type DownloadRequest struct {
dep DataDeployment
hashWriter hash.Hash
bundleFile string
backoffFunc func()
markFailedAt time.Time
}
func (r *DownloadRequest) downloadBundle() {
dep := r.dep
log.Debugf("starting bundle download attempt for %s: %s", dep.ID, dep.BundleURI)
deployments, err := getDeployments("WHERE id=$1", dep.ID)
if err == nil && len(deployments) == 0 {
log.Debugf("never mind, deployment %s was deleted", dep.ID)
return
}
r.checkTimeout()
r.hashWriter.Reset()
tempFile, err := downloadFromURI(dep.BundleURI, r.hashWriter, dep.BundleChecksum)
if err == nil {
err = os.Rename(tempFile, r.bundleFile)
if err != nil {
log.Errorf("Unable to rename temp bundle file %s to %s: %s", tempFile, r.bundleFile, err)
}
}
if tempFile != "" {
go safeDelete(tempFile)
}
if err == nil {
err = updateLocalBundleURI(dep.ID, r.bundleFile)
}
if err != nil {
// add myself back into the queue after back off
go func() {
r.backoffFunc()
downloadQueue <- r
}()
return
}
log.Debugf("bundle for %s downloaded: %s", dep.ID, dep.BundleURI)
// send deployments to client
deploymentsChanged <- dep.ID
}
func (r *DownloadRequest) checkTimeout() {
if !r.markFailedAt.IsZero() {
if time.Now().After(r.markFailedAt) {
r.markFailedAt = time.Time{}
log.Debugf("bundle download timeout. marking deployment %s failed. will keep retrying: %s",
r.dep.ID, r.dep.BundleURI)
setDeploymentResults(apiDeploymentResults{
{
ID: r.dep.ID,
Status: RESPONSE_STATUS_FAIL,
ErrorCode: TRACKER_ERR_BUNDLE_DOWNLOAD_TIMEOUT,
Message: "bundle download failed",
},
})
}
}
}
func getBundleFile(dep DataDeployment) string {
// the content of the URI is unfortunately not guaranteed not to change, so I can't just use dep.BundleURI
// unfortunately, this also means that a bundle cache isn't especially relevant
fileName := dep.DataScopeID + "_" + dep.ID
return path.Join(bundlePath, base64.StdEncoding.EncodeToString([]byte(fileName)))
}
func downloadFromURI(uri string, hashWriter hash.Hash, expectedHash string) (tempFileName string, err error) {
log.Debugf("Downloading bundle: %s", uri)
var tempFile *os.File
tempFile, err = ioutil.TempFile(bundlePath, "download")
if err != nil {
log.Errorf("Unable to create temp file: %v", err)
return
}
defer tempFile.Close()
tempFileName = tempFile.Name()
var bundleReader io.ReadCloser
bundleReader, err = getURIFileReader(uri)
if err != nil {
log.Errorf("Unable to retrieve bundle %s: %v", uri, err)
return
}
defer bundleReader.Close()
// track checksum
teedReader := io.TeeReader(bundleReader, hashWriter)
_, err = io.Copy(tempFile, teedReader)
if err != nil {
log.Errorf("Unable to write bundle %s: %v", tempFileName, err)
return
}
// check checksum
checksum := hex.EncodeToString(hashWriter.Sum(nil))
if checksum != expectedHash {
err = errors.New(fmt.Sprintf("Bad checksum on %s. calculated: %s, given: %s", tempFileName, checksum, expectedHash))
log.Error(err.Error())
return
}
log.Debugf("Bundle %s downloaded to: %s", uri, tempFileName)
return
}
// retrieveBundle retrieves bundle data from a URI
func getURIFileReader(uriString string) (io.ReadCloser, error) {
uri, err := url.Parse(uriString)
if err != nil {
return nil, fmt.Errorf("DownloadFileUrl: Failed to parse urlStr: %s", uriString)
}
// todo: add authentication - TBD?
// assume it's a file if no scheme - todo: remove file support?
if uri.Scheme == "" || uri.Scheme == "file" {
f, err := os.Open(uri.Path)
if err != nil {
return nil, err
}
return f, nil
}
// GET the contents at uriString
client := http.Client{
Timeout: bundleDownloadConnTimeout,
}
res, err := client.Get(uriString)
if err != nil {
return nil, err
}
if res.StatusCode != 200 {
return nil, fmt.Errorf("Bundle uri %s failed with status %d", uriString, res.StatusCode)
}
return res.Body, nil
}
func getHashWriter(hashType string) (hash.Hash, error) {
var hashWriter hash.Hash
switch strings.ToLower(hashType) {
case "":
hashWriter = fakeHash{md5.New()}
case "md5":
hashWriter = md5.New()
case "crc32":
hashWriter = crc32.NewIEEE()
case "sha256":
hashWriter = sha256.New()
case "sha512":
hashWriter = sha512.New()
default:
return nil, errors.New(
fmt.Sprintf("invalid checksumType: %s. valid types: md5, crc32, sha256, sha512", hashType))
}
return hashWriter, nil
}
type fakeHash struct {
hash.Hash
}
func (f fakeHash) Sum(b []byte) []byte {
return []byte("")
}
func initializeBundleDownloading() {
// create workers
for i := 0; i < concurrentDownloads; i++ {
worker := BundleDownloader{
id: i + 1,
workChan: make(chan *DownloadRequest),
quitChan: make(chan bool),
}
worker.Start()
}
// run dispatcher
go func() {
for {
select {
case req := <-downloadQueue:
log.Debugf("dispatching downloader for: %s", req.bundleFile)
go func() {
worker := <-workerQueue
log.Debugf("got a worker for: %s", req.bundleFile)
worker <- req
}()
}
}
}()
}
type BundleDownloader struct {
id int
workChan chan *DownloadRequest
quitChan chan bool
}
func (w *BundleDownloader) Start() {
go func() {
log.Debugf("started bundle downloader %d", w.id)
for {
// wait for work
workerQueue <- w.workChan
select {
case req := <-w.workChan:
log.Debugf("starting download %s", req.bundleFile)
req.downloadBundle()
case <-w.quitChan:
log.Debugf("bundle downloader %d stopped", w.id)
return
}
}
}()
}
func (w *BundleDownloader) Stop() {
go func() {
w.quitChan <- true
}()
}