S3 Binary Cache Store

Store URL format: s3://bucket-name

This store allows reading and writing a binary cache stored in an AWS S3 (or S3-compatible service) bucket. This store shares many idioms with the HTTP Binary Cache Store.

For AWS S3, the binary cache URL for a bucket named example-nix-cache will be exactly s3://example-nix-cache. For S3 compatible binary caches, consult that cache's documentation.

Anonymous reads to your S3-compatible binary cache

If your binary cache is publicly accessible and does not require authentication, it is simplest to use the [HTTP Binary Cache Store] rather than S3 Binary Cache Store with https://example-nix-cache.s3.amazonaws.com instead of s3://example-nix-cache.

Your bucket will need a bucket policy like the following to be accessible:

{
    "Id": "DirectReads",
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AllowDirectReads",
            "Action": [
                "s3:GetObject",
                "s3:GetBucketLocation",
                "s3:ListBucket"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:s3:::example-nix-cache",
                "arn:aws:s3:::example-nix-cache/*"
            ],
            "Principal": "*"
        }
    ]
}

Authentication

Nix will use the default credential provider chain for authenticating requests to Amazon S3.

Note that this means Nix will read environment variables and files with different idioms than with Nix's own settings, as implemented by the AWS SDK. Consult the documentation linked above for further details.

Authenticated reads to your S3 binary cache

Your bucket will need a bucket policy allowing the desired users to perform the s3:GetObject, s3:GetBucketLocation, and s3:ListBucket actions on all objects in the bucket. The anonymous policy given above can be updated to have a restricted Principal to support this.

Authenticated writes to your S3-compatible binary cache

Your account will need an IAM policy to support uploading to the bucket:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "UploadToCache",
      "Effect": "Allow",
      "Action": [
        "s3:AbortMultipartUpload",
        "s3:GetBucketLocation",
        "s3:GetObject",
        "s3:ListBucket",
        "s3:ListBucketMultipartUploads",
        "s3:ListMultipartUploadParts",
        "s3:PutObject"
      ],
      "Resource": [
        "arn:aws:s3:::example-nix-cache",
        "arn:aws:s3:::example-nix-cache/*"
      ]
    }
  ]
}

Examples

With bucket policies and authentication set up as described above, uploading works via nix copy (experimental).

  • To upload with a specific credential profile for Amazon S3:

    $ nix copy nixpkgs.hello \
  --to 's3://example-nix-cache?profile=cache-upload&region=eu-west-2'

  • To upload to an S3-compatible binary cache:

    $ nix copy nixpkgs.hello --to \
  's3://example-nix-cache?profile=cache-upload&scheme=https&endpoint=minio.example.com'

Settings

  • compression

    NAR compression method (xz, bzip2, gzip, zstd, or none).

    Default: xz

  • compression-level

    The preset level to be used when compressing NARs. The meaning and accepted values depend on the compression method selected. -1 specifies that the default compression level should be used.

    Default: -1

  • endpoint

    The S3 endpoint to use. When empty (default), uses AWS S3 with region-specific endpoints (e.g., s3.us-east-1.amazonaws.com). For S3-compatible services such as MinIO, set this to your service's endpoint.

    Note

    Custom endpoints must support HTTPS and use path-based addressing instead of virtual host based addressing.

    Default: empty

  • index-debug-info

    Whether to index DWARF debug info files by build ID. This allows dwarffs to fetch debug info on demand

    Default: false

  • local-nar-cache

    Path to a local cache of NARs fetched from this binary cache, used by commands such as nix store cat.

    Default: empty

  • log-compression

    Compression method for log/* files. It is recommended to use a compression method supported by most web browsers (e.g. brotli).

    Default: empty

  • ls-compression

    Compression method for .ls files.

    Default: empty

  • multipart-chunk-size

    The size (in bytes) of each part in multipart uploads. Must be at least 5 MiB (AWS S3 requirement). Larger chunk sizes reduce the number of requests but use more memory. Default is 5 MiB.

    Default: 5242880

    Deprecated alias: buffer-size

  • multipart-threshold

    The minimum file size (in bytes) for using multipart uploads. Files smaller than this threshold will use regular PUT requests. Default is 100 MiB. Only takes effect when multipart-upload is enabled.

    Default: 104857600

  • multipart-upload

    Whether to use multipart uploads for large files. When enabled, files exceeding the multipart threshold will be uploaded in multiple parts, which is required for files larger than 5 GiB and can improve performance and reliability for large uploads.

    Default: false

  • narinfo-compression

    Compression method for .narinfo files.

    Default: empty

  • parallel-compression

    Enable multi-threaded compression of NARs. This is currently only available for xz and zstd.

    Default: false

  • path-info-cache-size

    Size of the in-memory store path metadata cache.

    Default: 65536

  • priority

    Priority of this store when used as a substituter. A lower value means a higher priority.

    Default: 0

  • profile

    The name of the AWS configuration profile to use. By default Nix uses the default profile.

    Default: default

  • region

    The region of the S3 bucket. If your bucket is not in us-east-1, you should always explicitly specify the region parameter.

    Default: us-east-1

  • scheme

    The scheme used for S3 requests, https (default) or http. This option allows you to disable HTTPS for binary caches which don't support it.

    Note

    HTTPS should be used if the cache might contain sensitive information.

    Default: https

  • secret-key

    Path to the secret key used to sign the binary cache.

    Default: empty

  • secret-keys

    List of comma-separated paths to the secret keys used to sign the binary cache.

    Default: empty

  • storage-class

    The S3 storage class to use for uploaded objects. When not set (default), uses the bucket's default storage class. Valid values include:

    • STANDARD (default, frequently accessed data)
    • REDUCED_REDUNDANCY (less frequently accessed data)
    • STANDARD_IA (infrequent access)
    • ONEZONE_IA (infrequent access, single AZ)
    • INTELLIGENT_TIERING (automatic cost optimization)
    • GLACIER (archival with retrieval times in minutes to hours)
    • DEEP_ARCHIVE (long-term archival with 12-hour retrieval)
    • GLACIER_IR (instant retrieval archival)

    See AWS S3 documentation for detailed storage class descriptions and pricing: https://docs.aws.amazon.com/AmazonS3/latest/userguide/storage-class-intro.html

    Default: ``

  • store

    Logical location of the Nix store, usually /nix/store. Note that you can only copy store paths between stores if they have the same store setting.

    Default: /nix/store

  • system-features

    Optional system features available on the system this store uses to build derivations.

    Example: "kvm"

    Default: machine-specific

  • trusted

    Whether paths from this store can be used as substitutes even if they are not signed by a key listed in the trusted-public-keys setting.

    Default: false

  • want-mass-query

    Whether this store can be queried efficiently for path validity when used as a substituter.

    Default: false

  • write-nar-listing

    Whether to write a JSON file that lists the files in each NAR.

    Default: false