Nix has built-in support for storing and fetching store paths from Amazon S3 and S3 compatible services. This uses the same binary cache mechanism that Nix usually uses to fetch prebuilt binaries from cache.nixos.org. The following options can be specified as URL parameters to the S3 URL: profile The name of the AWS configuration profile to use. By default Nix will use the default profile. region The region of the S3 bucket. us–east-1 by default. If your bucket is not in us–east-1, you should always explicitly specify the region parameter. endpoint The URL to your S3-compatible service, for when not using Amazon S3. Do not specify this value if you're using Amazon S3. This endpoint must support HTTPS and will use path-based addressing instead of virtual host based addressing. 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. HTTPS should be used if the cache might contain sensitive information. In this example we will use the bucket named example-nix-cache.

If your binary cache is publicly accessible and does not require authentication, the simplest and easiest way to use Nix with your S3 compatible binary cache is to use the HTTP URL for that cache. For AWS S3 the binary cache URL for example bucket will be exactly https://example-nix-cache.s3.amazonaws.com or s3://example-nix-cache. For S3 compatible binary caches, consult that cache's documentation. Your bucket will need the following bucket policy:

For AWS S3 the binary cache URL for example bucket will be exactly s3://example-nix-cache. Nix will use the default credential provider chain for authenticating requests to Amazon S3. Nix supports authenticated reads from Amazon S3 and S3 compatible binary caches. Your bucket will need a bucket policy allowing the desired users to perform the s3:GetObject and s3:GetBucketLocation action on all objects in the bucket. The anonymous policy in can be updated to have a restricted Principal to support this.

Nix support fully supports writing to Amazon S3 and S3 compatible buckets. The binary cache URL for our example bucket will be s3://example-nix-cache. Nix will use the default credential provider chain for authenticating requests to Amazon S3. Your account will need the following IAM policy to upload to the cache: nix copy --to 's3://example-nix-cache?profile=cache-upload&region=eu-west-2' nixpkgs.hello nix copy --to 's3://example-nix-cache?profile=cache-upload&scheme=https&endpoint=minio.example.com' nixpkgs.hello