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package getter
import (
"fmt"
"io"
"net/url"
"os"
"path/filepath"
"strings"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/credentials"
"github.com/aws/aws-sdk-go/aws/credentials/ec2rolecreds"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/s3"
)
// S3Getter is a Getter implementation that will download a module from
// a S3 bucket.
type S3Getter struct{}
func (g *S3Getter) Get(dst string, u *url.URL) error {
// Parse URL
region, bucket, path, _, creds, err := g.parseUrl(u)
if err != nil {
return err
}
// Remove destination if it already exists
_, err = os.Stat(dst)
if err != nil && !os.IsNotExist(err) {
return err
}
if err == nil {
// Remove the destination
if err := os.RemoveAll(dst); err != nil {
return err
}
}
// Create all the parent directories
if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
return err
}
config := g.getAWSConfig(region, creds)
sess := session.New(config)
client := s3.New(sess)
// List files in path, keep listing until no more objects are found
lastMarker := ""
hasMore := true
for hasMore {
req := &s3.ListObjectsInput{
Bucket: aws.String(bucket),
Prefix: aws.String(path),
}
if lastMarker != "" {
req.Marker = aws.String(lastMarker)
}
resp, err := client.ListObjects(req)
if err != nil {
return err
}
hasMore = aws.BoolValue(resp.IsTruncated)
// Get each object storing each file relative to the destination path
for _, object := range resp.Contents {
lastMarker = aws.StringValue(object.Key)
objPath := aws.StringValue(object.Key)
// If the key ends with a backslash assume it is a directory and ignore
if strings.HasSuffix(objPath, "/") {
continue
}
// Get the object destination path
objDst, err := filepath.Rel(path, objPath)
if err != nil {
return err
}
objDst = filepath.Join(dst, objDst)
if err := g.getObject(client, objDst, bucket, objPath, ""); err != nil {
return err
}
}
}
return nil
}
func (g *S3Getter) GetFile(dst string, u *url.URL) error {
region, bucket, path, version, creds, err := g.parseUrl(u)
if err != nil {
return err
}
config := g.getAWSConfig(region, creds)
sess := session.New(config)
client := s3.New(sess)
return g.getObject(client, dst, bucket, path, version)
}
func (g *S3Getter) getObject(client *s3.S3, dst, bucket, key, version string) error {
req := &s3.GetObjectInput{
Bucket: aws.String(bucket),
Key: aws.String(key),
}
if version != "" {
req.VersionId = aws.String(version)
}
resp, err := client.GetObject(req)
if err != nil {
return err
}
// Create all the parent directories
if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
return err
}
f, err := os.Create(dst)
if err != nil {
return err
}
defer f.Close()
_, err = io.Copy(f, resp.Body)
return err
}
func (g *S3Getter) getAWSConfig(region string, creds *credentials.Credentials) *aws.Config {
conf := &aws.Config{}
if creds == nil {
creds = credentials.NewChainCredentials(
[]credentials.Provider{
&credentials.EnvProvider{},
&credentials.SharedCredentialsProvider{Filename: "", Profile: ""},
&ec2rolecreds.EC2RoleProvider{ExpiryWindow: 5 * time.Minute},
})
}
conf.Credentials = creds
if region != "" {
conf.Region = aws.String(region)
}
return conf
}
func (g *S3Getter) parseUrl(u *url.URL) (region, bucket, path, version string, creds *credentials.Credentials, err error) {
// Expected host style: s3.amazonaws.com. They always have 3 parts,
// although the first may differ if we're accessing a specific region.
hostParts := strings.Split(u.Host, ".")
if len(hostParts) != 3 {
err = fmt.Errorf("URL is not a valid S3 URL")
return
}
// Parse the region out of the first part of the host
region = strings.TrimPrefix(strings.TrimPrefix(hostParts[0], "s3-"), "s3")
if region == "" {
region = "us-east-1"
}
pathParts := strings.SplitN(u.Path, "/", 3)
if len(pathParts) != 3 {
err = fmt.Errorf("URL is not a valid S3 URL")
return
}
bucket = pathParts[1]
path = pathParts[2]
version = u.Query().Get("version")
_, hasAwsId := u.Query()["aws_access_key_id"]
_, hasAwsSecret := u.Query()["aws_access_key_secret"]
_, hasAwsToken := u.Query()["aws_access_token"]
if hasAwsId || hasAwsSecret || hasAwsToken {
creds = credentials.NewStaticCredentials(
u.Query().Get("aws_access_key_id"),
u.Query().Get("aws_access_key_secret"),
u.Query().Get("aws_access_token"),
)
}
return
}
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