github.com/lusis/distribution@v2.0.1+incompatible/registry/storage/driver/middleware/cloudfront/middleware.go (about)

     1  // Package middleware - cloudfront wrapper for storage libs
     2  // N.B. currently only works with S3, not arbitrary sites
     3  //
     4  package middleware
     5  
     6  import (
     7  	"crypto/x509"
     8  	"encoding/pem"
     9  	"fmt"
    10  	"io/ioutil"
    11  	"time"
    12  
    13  	"github.com/AdRoll/goamz/cloudfront"
    14  	"github.com/docker/distribution/context"
    15  	storagedriver "github.com/docker/distribution/registry/storage/driver"
    16  	storagemiddleware "github.com/docker/distribution/registry/storage/driver/middleware"
    17  )
    18  
    19  // cloudFrontStorageMiddleware provides an simple implementation of layerHandler that
    20  // constructs temporary signed CloudFront URLs from the storagedriver layer URL,
    21  // then issues HTTP Temporary Redirects to this CloudFront content URL.
    22  type cloudFrontStorageMiddleware struct {
    23  	storagedriver.StorageDriver
    24  	cloudfront *cloudfront.CloudFront
    25  	duration   time.Duration
    26  }
    27  
    28  var _ storagedriver.StorageDriver = &cloudFrontStorageMiddleware{}
    29  
    30  // newCloudFrontLayerHandler constructs and returns a new CloudFront
    31  // LayerHandler implementation.
    32  // Required options: baseurl, privatekey, keypairid
    33  func newCloudFrontStorageMiddleware(storageDriver storagedriver.StorageDriver, options map[string]interface{}) (storagedriver.StorageDriver, error) {
    34  	base, ok := options["baseurl"]
    35  	if !ok {
    36  		return nil, fmt.Errorf("No baseurl provided")
    37  	}
    38  	baseURL, ok := base.(string)
    39  	if !ok {
    40  		return nil, fmt.Errorf("baseurl must be a string")
    41  	}
    42  	pk, ok := options["privatekey"]
    43  	if !ok {
    44  		return nil, fmt.Errorf("No privatekey provided")
    45  	}
    46  	pkPath, ok := pk.(string)
    47  	if !ok {
    48  		return nil, fmt.Errorf("privatekey must be a string")
    49  	}
    50  	kpid, ok := options["keypairid"]
    51  	if !ok {
    52  		return nil, fmt.Errorf("No keypairid provided")
    53  	}
    54  	keypairID, ok := kpid.(string)
    55  	if !ok {
    56  		return nil, fmt.Errorf("keypairid must be a string")
    57  	}
    58  
    59  	pkBytes, err := ioutil.ReadFile(pkPath)
    60  	if err != nil {
    61  		return nil, fmt.Errorf("Failed to read privatekey file: %s", err)
    62  	}
    63  
    64  	block, _ := pem.Decode([]byte(pkBytes))
    65  	if block == nil {
    66  		return nil, fmt.Errorf("Failed to decode private key as an rsa private key")
    67  	}
    68  	privateKey, err := x509.ParsePKCS1PrivateKey(block.Bytes)
    69  	if err != nil {
    70  		return nil, err
    71  	}
    72  
    73  	cf := cloudfront.New(baseURL, privateKey, keypairID)
    74  
    75  	duration := 20 * time.Minute
    76  	d, ok := options["duration"]
    77  	if ok {
    78  		switch d := d.(type) {
    79  		case time.Duration:
    80  			duration = d
    81  		case string:
    82  			dur, err := time.ParseDuration(d)
    83  			if err != nil {
    84  				return nil, fmt.Errorf("Invalid duration: %s", err)
    85  			}
    86  			duration = dur
    87  		}
    88  	}
    89  
    90  	return &cloudFrontStorageMiddleware{StorageDriver: storageDriver, cloudfront: cf, duration: duration}, nil
    91  }
    92  
    93  // S3BucketKeyer is any type that is capable of returning the S3 bucket key
    94  // which should be cached by AWS CloudFront.
    95  type S3BucketKeyer interface {
    96  	S3BucketKey(path string) string
    97  }
    98  
    99  // Resolve returns an http.Handler which can serve the contents of the given
   100  // Layer, or an error if not supported by the storagedriver.
   101  func (lh *cloudFrontStorageMiddleware) URLFor(path string, options map[string]interface{}) (string, error) {
   102  	// TODO(endophage): currently only supports S3
   103  	keyer, ok := lh.StorageDriver.(S3BucketKeyer)
   104  	if !ok {
   105  		context.GetLogger(context.Background()).Warn("the CloudFront middleware does not support this backend storage driver")
   106  		return lh.StorageDriver.URLFor(path, options)
   107  	}
   108  
   109  	cfURL, err := lh.cloudfront.CannedSignedURL(keyer.S3BucketKey(path), "", time.Now().Add(lh.duration))
   110  	if err != nil {
   111  		return "", err
   112  	}
   113  	return cfURL, nil
   114  }
   115  
   116  // init registers the cloudfront layerHandler backend.
   117  func init() {
   118  	storagemiddleware.Register("cloudfront", storagemiddleware.InitFunc(newCloudFrontStorageMiddleware))
   119  }