Add S3-compatible storage backend

internal/adapters/s3/options.go

@@ -0,0 +1,42 @@
+package s3
+
+import (
+	"fmt"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/distributor/internal/storage"
+)
+
+const BackendName = "s3"
+
+const DefaultRegion = "us-east-1"
+
+type Options struct {
+	Endpoint        string
+	Bucket          string
+	Prefix          string
+	Region          string
+	ForcePathStyle  bool
+	AccessKeyID     string
+	SecretAccessKey string
+}
+
+func (o Options) normalized() (Options, error) {
+	if o.Endpoint == "" {
+		return Options{}, fmt.Errorf("endpoint is required")
+	}
+	if o.Bucket == "" {
+		return Options{}, fmt.Errorf("bucket is required")
+	}
+	if o.Region == "" {
+		o.Region = DefaultRegion
+	}
+	o.Prefix = strings.Trim(o.Prefix, "/")
+	if err := storage.ValidatePrefix(o.Prefix); err != nil {
+		return Options{}, fmt.Errorf("prefix: %w", err)
+	}
+	if (o.AccessKeyID == "") != (o.SecretAccessKey == "") {
+		return Options{}, fmt.Errorf("access key id and secret access key must be configured together")
+	}
+	return o, nil
+}