chore(stdiscosrv): clean up s3 handling

cmd/stdiscosrv/s3.go

@@ -0,0 +1,97 @@
+// Copyright (C) 2024 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package main
+
+import (
+	"io"
+	"log"
+	"time"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"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/aws/aws-sdk-go/service/s3/s3manager"
+)
+
+type s3Copier struct {
+	endpoint    string
+	region      string
+	bucket      string
+	key         string
+	accessKeyID string
+	secretKey   string
+}
+
+func newS3Copier(endpoint, region, bucket, key, accessKeyID, secretKey string) *s3Copier {
+	return &s3Copier{
+		endpoint:    endpoint,
+		region:      region,
+		bucket:      bucket,
+		key:         key,
+		accessKeyID: accessKeyID,
+		secretKey:   secretKey,
+	}
+}
+
+func (s *s3Copier) upload(r io.Reader) error {
+	sess, err := session.NewSession(&aws.Config{
+		Region:      aws.String(s.region),
+		Endpoint:    aws.String(s.endpoint),
+		Credentials: credentials.NewStaticCredentials(s.accessKeyID, s.secretKey, ""),
+	})
+	if err != nil {
+		return err
+	}
+
+	uploader := s3manager.NewUploader(sess)
+	_, err = uploader.Upload(&s3manager.UploadInput{
+		Bucket: aws.String(s.bucket),
+		Key:    aws.String(s.key),
+		Body:   r,
+	})
+	return err
+}
+
+func (s *s3Copier) downloadLatest(w io.WriterAt) error {
+	sess, err := session.NewSession(&aws.Config{
+		Region:      aws.String(s.region),
+		Endpoint:    aws.String(s.endpoint),
+		Credentials: credentials.NewStaticCredentials(s.accessKeyID, s.secretKey, ""),
+	})
+	if err != nil {
+		return err
+	}
+
+	svc := s3.New(sess)
+	resp, err := svc.ListObjectsV2(&s3.ListObjectsV2Input{Bucket: aws.String(s.bucket)})
+	if err != nil {
+		return err
+	}
+
+	var lastKey string
+	var lastModified time.Time
+	var lastSize int64
+	for _, item := range resp.Contents {
+		if item.LastModified.After(lastModified) && *item.Size > lastSize {
+			lastKey = *item.Key
+			lastModified = *item.LastModified
+			lastSize = *item.Size
+		} else if lastModified.Sub(*item.LastModified) < 5*time.Minute && *item.Size > lastSize {
+			lastKey = *item.Key
+			lastSize = *item.Size
+		}
+	}
+
+	log.Println("Downloading database from", lastKey)
+	downloader := s3manager.NewDownloader(sess)
+	_, err = downloader.Download(w, &s3.GetObjectInput{
+		Bucket: aws.String(s.bucket),
+		Key:    aws.String(lastKey),
+	})
+	return err
+}