138 lines
3.9 KiB
Go
138 lines
3.9 KiB
Go
// Package middleware - cloudfront wrapper for storage libs
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// N.B. currently only works with S3, not arbitrary sites
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//
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package middleware
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import (
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"context"
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"crypto/x509"
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"encoding/pem"
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"fmt"
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"io/ioutil"
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"net/url"
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"strings"
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"time"
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"github.com/aws/aws-sdk-go/service/cloudfront/sign"
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dcontext "github.com/docker/distribution/context"
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storagedriver "github.com/docker/distribution/registry/storage/driver"
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storagemiddleware "github.com/docker/distribution/registry/storage/driver/middleware"
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)
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// cloudFrontStorageMiddleware provides a simple implementation of layerHandler that
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// constructs temporary signed CloudFront URLs from the storagedriver layer URL,
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// then issues HTTP Temporary Redirects to this CloudFront content URL.
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type cloudFrontStorageMiddleware struct {
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storagedriver.StorageDriver
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urlSigner *sign.URLSigner
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baseURL string
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duration time.Duration
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}
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var _ storagedriver.StorageDriver = &cloudFrontStorageMiddleware{}
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// newCloudFrontLayerHandler constructs and returns a new CloudFront
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// LayerHandler implementation.
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// Required options: baseurl, privatekey, keypairid
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func newCloudFrontStorageMiddleware(storageDriver storagedriver.StorageDriver, options map[string]interface{}) (storagedriver.StorageDriver, error) {
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base, ok := options["baseurl"]
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if !ok {
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return nil, fmt.Errorf("no baseurl provided")
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}
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baseURL, ok := base.(string)
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if !ok {
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return nil, fmt.Errorf("baseurl must be a string")
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}
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if !strings.Contains(baseURL, "://") {
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baseURL = "https://" + baseURL
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}
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if !strings.HasSuffix(baseURL, "/") {
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baseURL += "/"
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}
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if _, err := url.Parse(baseURL); err != nil {
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return nil, fmt.Errorf("invalid baseurl: %v", err)
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}
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pk, ok := options["privatekey"]
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if !ok {
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return nil, fmt.Errorf("no privatekey provided")
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}
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pkPath, ok := pk.(string)
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if !ok {
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return nil, fmt.Errorf("privatekey must be a string")
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}
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kpid, ok := options["keypairid"]
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if !ok {
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return nil, fmt.Errorf("no keypairid provided")
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}
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keypairID, ok := kpid.(string)
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if !ok {
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return nil, fmt.Errorf("keypairid must be a string")
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}
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pkBytes, err := ioutil.ReadFile(pkPath)
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if err != nil {
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return nil, fmt.Errorf("failed to read privatekey file: %s", err)
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}
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block, _ := pem.Decode([]byte(pkBytes))
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if block == nil {
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return nil, fmt.Errorf("failed to decode private key as an rsa private key")
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}
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privateKey, err := x509.ParsePKCS1PrivateKey(block.Bytes)
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if err != nil {
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return nil, err
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}
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urlSigner := sign.NewURLSigner(keypairID, privateKey)
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duration := 20 * time.Minute
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d, ok := options["duration"]
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if ok {
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switch d := d.(type) {
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case time.Duration:
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duration = d
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case string:
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dur, err := time.ParseDuration(d)
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if err != nil {
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return nil, fmt.Errorf("invalid duration: %s", err)
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}
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duration = dur
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}
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}
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return &cloudFrontStorageMiddleware{
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StorageDriver: storageDriver,
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urlSigner: urlSigner,
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baseURL: baseURL,
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duration: duration,
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}, nil
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}
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// S3BucketKeyer is any type that is capable of returning the S3 bucket key
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// which should be cached by AWS CloudFront.
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type S3BucketKeyer interface {
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S3BucketKey(path string) string
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}
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// Resolve returns an http.Handler which can serve the contents of the given
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// Layer, or an error if not supported by the storagedriver.
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func (lh *cloudFrontStorageMiddleware) URLFor(ctx context.Context, path string, options map[string]interface{}) (string, error) {
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// TODO(endophage): currently only supports S3
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keyer, ok := lh.StorageDriver.(S3BucketKeyer)
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if !ok {
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dcontext.GetLogger(ctx).Warn("the CloudFront middleware does not support this backend storage driver")
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return lh.StorageDriver.URLFor(ctx, path, options)
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}
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cfURL, err := lh.urlSigner.Sign(lh.baseURL+keyer.S3BucketKey(path), time.Now().Add(lh.duration))
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if err != nil {
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return "", err
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}
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return cfURL, nil
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}
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// init registers the cloudfront layerHandler backend.
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func init() {
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storagemiddleware.Register("cloudfront", storagemiddleware.InitFunc(newCloudFrontStorageMiddleware))
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}
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