Added image resizer for responsive web apps

example-project/internal/platform/deploy/cloudfront.go

@@ -0,0 +1,163 @@
+package deploy
+
+import (
+	"fmt"
+	"net/url"
+	"path/filepath"
+	"strings"
+
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/cloudfront"
+	"github.com/pkg/errors"
+)
+
+func CloudFrontDistribution(awsSession *session.Session, s3Bucket string) (*cloudfront.DistributionSummary, error) {
+	// Init new CloudFront using provided AWS session.
+	cloudFront := cloudfront.New(awsSession)
+
+	// Loop through all the cloudfront distributions and find the one that matches the
+	// S3 Bucket name. AWS doesn't current support multiple distributions per bucket
+	// so this should always be a one to one match.
+	var distribution *cloudfront.DistributionSummary
+	err := cloudFront.ListDistributionsPages(&cloudfront.ListDistributionsInput{},
+		func(page *cloudfront.ListDistributionsOutput, lastPage bool) bool {
+			if page.DistributionList != nil {
+				for _, v := range page.DistributionList.Items {
+					if v.DomainName == nil || v.Origins == nil || v.Origins.Items == nil {
+						continue
+					}
+
+					for _, o := range v.Origins.Items {
+						if o.DomainName == nil || !strings.HasPrefix(*o.DomainName, s3Bucket+".") {
+							continue
+						}
+
+						distribution = v
+						break
+					}
+
+					if distribution != nil {
+						break
+					}
+				}
+			}
+
+			if distribution != nil {
+				return false
+			}
+
+			return !lastPage
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	if distribution == nil {
+		return nil, errors.Errorf("aws cloud front deployment does not exist for s3 bucket %s.", s3Bucket)
+	}
+
+	return distribution, nil
+}
+
+// NewAuthenticator creates an *Authenticator for use.
+// key expiration is optional to filter out old keys
+// It will error if:
+// - The aws session is nil.
+// - The aws s3 bucket is blank.
+func S3UrlFormatter(awsSession *session.Session, s3Bucket, s3KeyPrefix string, enableCloudFront bool) (func(string) string, error) {
+	if awsSession == nil {
+		return nil, errors.New("aws session cannot be nil")
+	}
+
+	if s3Bucket == "" {
+		return nil, errors.New("aws s3 bucket cannot be empty")
+	}
+
+	var (
+		baseS3Url    string
+		baseS3Origin string
+	)
+	if enableCloudFront {
+		dist, err := CloudFrontDistribution(awsSession, s3Bucket)
+		if err != nil {
+			return nil, err
+		}
+
+		// Format the domain as an HTTPS url, "dzuyel7n94hma.cloudfront.net"
+		baseS3Url = fmt.Sprintf("https://%s/", *dist.DomainName)
+
+		// The origin used for the cloudfront needs to be striped from the path
+		// provided, the URL shouldn't have one, but "/public"
+		baseS3Origin = *dist.Origins.Items[0].OriginPath
+	} else {
+		// The static files are upload to a specific prefix, so need to ensure
+		// the path reference includes this prefix
+		s3Path := filepath.Join(s3Bucket, s3KeyPrefix)
+
+		if *awsSession.Config.Region == "us-east-1" {
+			// US East (N.Virginia) region endpoint, http://s3.amazonaws.com/bucket or
+			// http://s3-external-1.amazonaws.com/bucket/
+			baseS3Url = fmt.Sprintf("https://s3.amazonaws.com/%s/", s3Path)
+		} else {
+			// Region-specific endpoint, http://s3-aws-region.amazonaws.com/bucket
+			baseS3Url = fmt.Sprintf("https://s3-%s.amazonaws.com/%s/", *awsSession.Config.Region, s3Path)
+		}
+
+		baseS3Origin = s3KeyPrefix
+	}
+
+	f := func(p string) string {
+		return S3Url(baseS3Url, baseS3Origin, p)
+	}
+
+	return f, nil
+}
+
+// S3Url formats a path to include either the S3 URL or a CloudFront
+// URL instead of serving the file from local file system.
+func S3Url(baseS3Url, baseS3Origin, p string) string {
+	// If its already a URL, then don't format it
+	if strings.HasPrefix(p, "http") {
+		return p
+	}
+
+	// Drop the beginning forward slash
+	p = strings.TrimLeft(p, "/")
+
+	// In the case of cloudfront, the base URL may not match S3,
+	// removing the origin from the path provided
+	// ie. The s3 bucket + path of
+	//		gitw-corp-web.s3.amazonaws.com/public
+	// 		maps to dzuyel7n94hma.cloudfront.net
+	//      where the path prefix of '/public' needs to be dropped.
+	org := strings.Trim(baseS3Origin, "/")
+	if org != "" {
+		p = strings.Replace(p, org+"/", "", 1)
+	}
+
+	// Parse out the querystring from the path
+	var pathQueryStr string
+	if strings.Contains(p, "?") {
+		pts := strings.Split(p, "?")
+		p = pts[0]
+		if len(pts) > 1 {
+			pathQueryStr = pts[1]
+		}
+	}
+
+	u, err := url.Parse(baseS3Url)
+	if err != nil {
+		return "?"
+	}
+	ldir := filepath.Base(u.Path)
+
+	if strings.HasPrefix(p, ldir) {
+		p = strings.Replace(p, ldir+"/", "", 1)
+	}
+
+	u.Path = filepath.Join(u.Path, p)
+	u.RawQuery = pathQueryStr
+
+	return u.String()
+}