streamLayeredImage Input Details: Architecture, Timestamps, User Credentials, and Layer Management

Must be an attribute set, with each attribute as listed in the [Docker Image Specification v1.3.0](https://github.com/moby/moby/blob/46f7ab808b9504d735d600e259ca0723f76fb164/image/spec/spec.md#image-json-field-descriptions). If any packages are used directly in `config`, they will be automatically included in the generated image. See [](#ex-dockerTools-streamLayeredImage-configclosure) for an example. _Default value:_ `null`. `architecture` (String; _optional_) : Used to specify the image architecture. This is useful for multi-architecture builds that don't need cross compiling. If specified, its value should follow the [OCI Image Configuration Specification](https://github.com/opencontainers/image-spec/blob/main/config.md#properties), which should still be compatible with Docker. According to the linked specification, all possible values for `$GOARCH` in [the Go docs](https://go.dev/doc/install/source#environment) should be valid, but will commonly be one of `386`, `amd64`, `arm`, or `arm64`. _Default value:_ the same value from `pkgs.go.GOARCH`. `created` (String; _optional_) : Specifies the time of creation of the generated image. This date will be used for the image metadata. This should be either a date and time formatted according to [ISO-8601](https://en.wikipedia.org/wiki/ISO_8601) or `"now"`, in which case the current date will be used. :::{.caution} Using `"now"` means that the generated image will not be reproducible anymore (because the date will always change whenever it's built). ::: _Default value:_ `"1970-01-01T00:00:01Z"`. `mtime` (String; _optional_) : Specifies the time used for the modification timestamp of files within the layers of the generated image. This should be either a date and time formatted according to [ISO-8601](https://en.wikipedia.org/wiki/ISO_8601) or `"now"`, in which case the current date will be used. :::{.caution} Using a non-constant date will cause built layers to have a different hash each time, preventing deduplication. Using `"now"` also means that the generated image will not be reproducible anymore (because the date will always change whenever it's built). ::: _Default value:_ `"1970-01-01T00:00:01Z"`. `uid` (Number; _optional_) []{#dockerTools-buildLayeredImage-arg-uid} `gid` (Number; _optional_) []{#dockerTools-buildLayeredImage-arg-gid} `uname` (String; _optional_) []{#dockerTools-buildLayeredImage-arg-uname} `gname` (String; _optional_) []{#dockerTools-buildLayeredImage-arg-gname} : Credentials for Nix store ownership. Can be overridden to e.g. `1000` / `1000` / `"user"` / `"user"` to enable building a container where Nix can be used as an unprivileged user in single-user mode. _Default value:_ `0` / `0` / `"root"` / `"root"` `maxLayers` (Number; _optional_) []{#dockerTools-buildLayeredImage-arg-maxLayers} : The maximum number of layers that will be used by the generated image. If a `fromImage` was specified, the number of layers used by `fromImage` will be subtracted from `maxLayers` to ensure that the image generated will have at most `maxLayers`. :::{.caution} Depending on the tool/runtime where the image will be used, there might be a limit to the number of layers that an image can have. For Docker, see [this issue on GitHub](https://github.com/docker/docs/issues/8230). ::: _Default value:_ 100. `extraCommands` (String; _optional_) : A bash script that will run in the context of the layer created with the contents specified by `contents`. At the moment this script runs, only the contents directly specified by `contents` will be available as links. _Default value:_ `""`. `fakeRootCommands` (String; _optional_) : A bash script that will run in the context of the layer created with the contents specified by `contents`. During the process to generate that layer, the script in `extraCommands` will be run first, if specified. After that, a {manpage}`fakeroot(1)` environment will be entered.

This section details the remaining inputs for the `streamLayeredImage` function. It covers `architecture` (specifying the image architecture), `created` (setting the image creation timestamp), `mtime` (setting file modification timestamps within layers), `uid`, `gid`, `uname`, `gname` (overriding Nix store ownership credentials), `maxLayers` (limiting the maximum number of layers), `extraCommands` (executing a bash script in the content layer context), and `fakeRootCommands` (executing a bash script in a fakeroot environment within the content layer). It emphasizes the importance of using static dates for reproducibility and the implications of exceeding layer limits.