Files
rclone/backend/s3
Nick Craig-Wood 891fddc28c s3: avoid buffering Object Lock uploads when the source MD5 is known
Single part uploads with Object Lock parameters need a Content-MD5
header, which the SDK can't compute from a stream, so the whole body
was read into memory with io.ReadAll to hash it - up to
--s3-upload-cutoff per file. prepareUpload already sets Content-MD5
from the source object's hash when it has one, so skip the buffering
entirely in that case and only buffer when the hash is unavailable.

When buffering is needed, read the body into a multipart.NewRW buffer
from the global pool, hashing in transit, so the memory is reused
across uploads and released after the request. The presigned request
path hands the body straight to http.NewRequest, so wrap it in
readers.NoCloser there to stop the transport closing the pooled buffer.
2026-09-01 14:21:52 +01:00
..
2026-08-20 12:12:00 +01:00

Adding a new s3 provider

It is quite easy to add a new S3 provider to rclone.

You'll then need to do add the following (optional tags are in [] and do not get displayed in rclone config if empty):

The process is as follows: Create yaml -> add docs -> run tests -> adjust yaml until tests pass.

All tags can be found in backend/s3/providers.go Provider Struct. Looking through a few of the yaml files as examples should make things clear. AWS.yaml as the most config. pasting.

YAML

In backend/s3/provider/YourProvider.yaml

  • name

  • description

    • More like the full name often "YourProvider + Object Storage"
  • [Region]

    • Any regions your provider supports or the defaults (use region: {} for this)
      • Example from AWS.yaml:

        region:
          us-east-1: |-
            The default endpoint - a good choice if you are unsure.
            US Region, Northern Virginia, or Pacific Northwest.
            Leave location constraint empty.
        
      • The defaults (as seen in Rclone.yaml):

        region:
          "": |-
            Use this if unsure.
            Will use v4 signatures and an empty region.
          other-v2-signature: |-
            Use this only if v4 signatures don't work.
            E.g. pre Jewel/v10 CEPH.
        
  • [Endpoint]

    • Any endpoints your provider supports

      • Example from Mega.yaml

          endpoint:
            s3.eu-central-1.s4.mega.io: Mega S4 eu-central-1 (Amsterdam)
        
  • [Location Constraint]

    • The Location Constraint of your remote, often same as region.
      • Example from AWS.yaml

        location_constraint:
          "": Empty for US Region, Northern Virginia, or Pacific Northwest
          us-east-2: US East (Ohio) Region
        
  • [ACL]

    • Identical across most providers. Select the default with acl: {}
      • Example from AWS.yaml

        acl:
          private: |-
            Owner gets FULL_CONTROL.
            No one else has access rights (default).
          public-read: |-
            Owner gets FULL_CONTROL.
            The AllUsers group gets READ access.
          public-read-write: |-
            Owner gets FULL_CONTROL.
            The AllUsers group gets READ and WRITE access.
            Granting this on a bucket is generally not recommended.
          authenticated-read: |-
            Owner gets FULL_CONTROL.
            The AuthenticatedUsers group gets READ access.
          bucket-owner-read: |-
            Object owner gets FULL_CONTROL.
            Bucket owner gets READ access.
            If you specify this canned ACL when creating a bucket, Amazon S3 ignores it.
          bucket-owner-full-control: |-
            Both the object owner and the bucket owner get FULL_CONTROL over the object.
            If you specify this canned ACL when creating a bucket, Amazon S3 ignores it.
        
  • [Storage Class]

    • Identical across most providers.
      • Defaults from AWS.yaml

        storage_class:
          "": Default
          STANDARD: Standard storage class
          REDUCED_REDUNDANCY: Reduced redundancy storage class
          STANDARD_IA: Standard Infrequent Access storage class
          ONEZONE_IA: One Zone Infrequent Access storage class
          GLACIER: Glacier Flexible Retrieval storage class
          DEEP_ARCHIVE: Glacier Deep Archive storage class
          INTELLIGENT_TIERING: Intelligent-Tiering storage class
          GLACIER_IR: Glacier Instant Retrieval storage class
        
  • [Server Side Encryption]

    • Not common, identical across most providers.
      • Defaults from AWS.yaml

          server_side_encryption:
            "": None
            AES256: AES256
            aws:kms: aws:kms
        
  • [Advanced Options]

    • All advanced options are Boolean - if true the configurator asks about that value, if not it doesn't:

      BucketACL             bool `yaml:"bucket_acl,omitempty"`
      DirectoryBucket       bool `yaml:"directory_bucket,omitempty"`
      LeavePartsOnError     bool `yaml:"leave_parts_on_error,omitempty"`
      RequesterPays         bool `yaml:"requester_pays,omitempty"`
      SSECustomerAlgorithm  bool `yaml:"sse_customer_algorithm,omitempty"`
      SSECustomerKey        bool `yaml:"sse_customer_key,omitempty"`
      SSECustomerKeyBase64  bool `yaml:"sse_customer_key_base64,omitempty"`
      SSECustomerKeyMd5     bool `yaml:"sse_customer_key_md5,omitempty"`
      SSEKmsKeyID           bool `yaml:"sse_kms_key_id,omitempty"`
      STSEndpoint           bool `yaml:"sts_endpoint,omitempty"`
      UseAccelerateEndpoint bool `yaml:"use_accelerate_endpoint,omitempty"`
      
      • Example from AWS.yaml:

        bucket_acl: true
        directory_bucket: true
        leave_parts_on_error: true
        requester_pays: true
        sse_customer_algorithm: true
        sse_customer_key: true
        sse_customer_key_base64: true
        sse_customer_key_md5: true
        sse_kms_key_id: true
        sts_endpoint: true
        use_accelerate_endpoint: true
        
  • Quirks

    • Quirks are discovered through documentation and running the tests as seen below.
      • Most quirks are *bool as to have 3 values, true, false and dont care.

        type Quirks struct {
            ListVersion           *int   `yaml:"list_version,omitempty"`     // 1 or 2
            ForcePathStyle        *bool  `yaml:"force_path_style,omitempty"` // true = path-style
            ListURLEncode         *bool  `yaml:"list_url_encode,omitempty"`
            UseMultipartEtag      *bool  `yaml:"use_multipart_etag,omitempty"`
            UseAlreadyExists      *bool  `yaml:"use_already_exists,omitempty"`
            UseAcceptEncodingGzip *bool  `yaml:"use_accept_encoding_gzip,omitempty"`
            MightGzip             *bool  `yaml:"might_gzip,omitempty"`
            UseMultipartUploads   *bool  `yaml:"use_multipart_uploads,omitempty"`
            UseUnsignedPayload    *bool  `yaml:"use_unsigned_payload,omitempty"`
            UseXID                *bool  `yaml:"use_x_id,omitempty"`
            SignAcceptEncoding    *bool  `yaml:"sign_accept_encoding,omitempty"`
            EtagIsNotMD5          *bool  `yaml:"etag_is_not_md5,omitempty"`
            CopyCutoff            *int64 `yaml:"copy_cutoff,omitempty"`
            MaxUploadParts        *int   `yaml:"max_upload_parts,omitempty"`
            MinChunkSize          *int64 `yaml:"min_chunk_size,omitempty"`
        }
        
        • Example from AWS.yaml

          quirks:
            might_gzip: false # Never auto gzips objects
            use_unsigned_payload: false # AWS has trailer support
          

Note that if you omit a section, eg region then the user won't be asked that question, and if you add an empty section e.g. region: {} then the defaults from the Other.yaml will be used.

DOCS

  • docs/content/s3.md
    • Add the provider at the top of the page.
    • Add a section about the provider linked from there.
      • Make sure this is in alphabetical order in the Providers section.
    • Add a transcript of a trial rclone config session
      • Edit the transcript to remove things which might change in subsequent versions
    • Do not alter or add to the autogenerated parts of s3.md
      • Rule of thumb: don't edit anything not mentioned above.
    • Do not run make backenddocs or bin/make_backend_docs.py s3
      • This will make autogenerated changes!
  • README.md - this is the home page in github
    • Add the provider and a link to the section you wrote in docs/contents/s3.md
  • docs/content/_index.md - this is the home page of rclone.org
    • Add the provider and a link to the section you wrote in docs/contents/s3.md
  • Once you've written the docs, run make serve and check they look OK in the web browser and the links (internal and external) all work.

TESTS

Once you've written the code, test rclone config works to your satisfaction and looks correct, and check the integration tests work go test -v -remote NewS3Provider:. You may need to adjust the quirks to get them to pass. Some providers just can't pass the tests with control characters in the names so if these fail and the provider doesn't support urlEncodeListings in the quirks then ignore them.