From b8af9fe60f27353bdd5933ed37508b30d4290046 Mon Sep 17 00:00:00 2001
From: Niall Sheridan <nsheridan@gmail.com>
Date: Sun, 5 Jun 2016 22:18:24 +0100
Subject: Add AWS S3 and Google GCS virtual filesystems.

This allows the signing key to be read directly from S3 using a path like
/s3/<bucket>/<path/to/signing.key> or /gcs/<bucket>/<path/to/signing.key>.
---
 server/fs/s3.go | 152 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)
 create mode 100644 server/fs/s3.go

(limited to 'server/fs/s3.go')

diff --git a/server/fs/s3.go b/server/fs/s3.go
new file mode 100644
index 0000000..4e82bb4
--- /dev/null
+++ b/server/fs/s3.go
@@ -0,0 +1,152 @@
+package fs
+
+import (
+	"bytes"
+	"errors"
+	"io/ioutil"
+	"os"
+	"path"
+	"strings"
+	"time"
+
+	"go4.org/wkfs"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/awserr"
+	"github.com/aws/aws-sdk-go/aws/credentials"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/s3"
+	"github.com/nsheridan/cashier/server/config"
+)
+
+func Register(config *config.AWS) {
+	ac := &aws.Config{}
+	// If region is unset the SDK will attempt to read the region from the environment.
+	if config.Region != "" {
+		ac.Region = aws.String(config.Region)
+	}
+	// Attempt to get credentials from the cashier config.
+	// Otherwise check for standard credentials. If neither are present register the fs as broken.
+	// TODO: implement this as a provider.
+	if config.AccessKey != "" && config.SecretKey != "" {
+		ac.Credentials = credentials.NewStaticCredentials(config.AccessKey, config.SecretKey, "")
+	} else {
+		_, err := session.New().Config.Credentials.Get()
+		if err != nil {
+			registerBrokenFS(errors.New("aws credentials not found"))
+			return
+		}
+	}
+	sc := s3.New(session.New(ac))
+	if aws.StringValue(sc.Config.Region) == "" {
+		registerBrokenFS(errors.New("aws region configuration not found"))
+		return
+	}
+	wkfs.RegisterFS("/s3/", &s3FS{
+		sc: sc,
+	})
+}
+
+func registerBrokenFS(err error) {
+	wkfs.RegisterFS("/s3/", &s3FS{
+		err: err,
+	})
+}
+
+type s3FS struct {
+	sc  *s3.S3
+	err error
+}
+
+func (fs *s3FS) parseName(name string) (bucket, fileName string, err error) {
+	if fs.err != nil {
+		return "", "", fs.err
+	}
+	name = strings.TrimPrefix(name, "/s3/")
+	i := strings.Index(name, "/")
+	if i < 0 {
+		return name, "", nil
+	}
+	return name[:i], name[i+1:], nil
+}
+
+// Open opens the named file for reading.
+func (fs *s3FS) Open(name string) (wkfs.File, error) {
+	bucket, fileName, err := fs.parseName(name)
+	if err != nil {
+		return nil, err
+	}
+	obj, err := fs.sc.GetObject(&s3.GetObjectInput{
+		Bucket: &bucket,
+		Key:    &fileName,
+	})
+	if err != nil {
+		return nil, err
+	}
+	defer obj.Body.Close()
+	slurp, err := ioutil.ReadAll(obj.Body)
+	if err != nil {
+		return nil, err
+	}
+	return &file{
+		name:   name,
+		Reader: bytes.NewReader(slurp),
+	}, nil
+}
+
+func (fs *s3FS) Stat(name string) (os.FileInfo, error) { return fs.Lstat(name) }
+func (fs *s3FS) Lstat(name string) (os.FileInfo, error) {
+	bucket, fileName, err := fs.parseName(name)
+	if err != nil {
+		return nil, err
+	}
+	obj, err := fs.sc.GetObject(&s3.GetObjectInput{
+		Bucket: &bucket,
+		Key:    &fileName,
+	})
+	if err != nil {
+		if awsErr, ok := err.(awserr.Error); ok {
+			if awsErr.Code() == "NoSuchKey" {
+				return nil, os.ErrNotExist
+			}
+		}
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &statInfo{
+		name: path.Base(fileName),
+		size: *obj.ContentLength,
+	}, nil
+}
+
+func (fs *s3FS) MkdirAll(path string, perm os.FileMode) error { return nil }
+
+func (fs *s3FS) OpenFile(name string, flag int, perm os.FileMode) (wkfs.FileWriter, error) {
+	return nil, errors.New("not implemented")
+}
+
+type statInfo struct {
+	name    string
+	size    int64
+	isDir   bool
+	modtime time.Time
+}
+
+func (si *statInfo) IsDir() bool        { return si.isDir }
+func (si *statInfo) ModTime() time.Time { return si.modtime }
+func (si *statInfo) Mode() os.FileMode  { return 0644 }
+func (si *statInfo) Name() string       { return path.Base(si.name) }
+func (si *statInfo) Size() int64        { return si.size }
+func (si *statInfo) Sys() interface{}   { return nil }
+
+type file struct {
+	name string
+	*bytes.Reader
+}
+
+func (*file) Close() error   { return nil }
+func (f *file) Name() string { return path.Base(f.name) }
+func (f *file) Stat() (os.FileInfo, error) {
+	panic("Stat not implemented on /s3/ files yet")
+}
-- 
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