nixpkgs/maintainers/scripts/bootstrap-files/README.md
Sergei Trofimovich 8a256ed0a7 maintainers/scripts/bootstrap-files: documentation and a script to update tarballs
This script attempts to document the exact procedure used to upload
bootstrap binaries used previously. I modeled it after most recent
https://github.com/NixOS/nixpkgs/pull/282517 upload.

There is one deviation from it to make it easier to handle mass updates
for https://github.com/NixOS/nixpkgs/issues/253713:

The binaries are expected to be stored in `stdenv/$target` (and not
something like `stdenv-linux/i686`.

The script handles both native and cross- linux targets. `darwin` will
need a bit more work to fin into this scheme, but it should be easy.

Example run to generate `i686-linux` update:

    $ maintainers/scripts/bootstrap-files/refresh-tarballs.bash --commit --targets=i686-unknown-linux-gnu
2024-01-28 14:48:18 +00:00

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Markdown

# Bootstrap files
Currently `nixpkgs` builds most of it's packages using bootstrap seed
binaries (without the reliance on external inputs):
- `bootstrap-tools`: an archive with the compiler toolchain and other
helper tools enough to build the rest of the `nixpkgs`.
- initial binaries needed to unpack `bootstrap-tools.*`. On `linux`
it's just `busybox`, on `darwin` it's `sh`, `bzip2`, `mkdir` and
`cpio`. These binaries can be executed directly from the store.
These are called "bootstrap files".
Bootstrap files should always be fetched from hydra and uploaded to
`tarballs.nixos.org` to guarantee that all the binaries were built from
the code committed into `nixpkgs` repository.
The uploads to `tarballs.nixos.org` are done by `@lovesegfault` today.
This document describes the procedure of updating bootstrap files in
`nixpkgs`.
## How to request the bootstrap seed update
To get the tarballs updated let's use an example `i686-unknown-linux-gnu`
target:
1. Create a local update:
```
$ maintainers/scripts/bootstrap-files/refresh-tarballs.bash --commit --targets=i686-unknown-linux-gnu
```
2. Test the update locally. I'll build local `hello` derivation with
the result:
```
$ nix-build -A hello --argstr system i686-linux
```
To validate cross-targets `binfmt` `NixOS` helper can be useful.
For `riscv64-unknown-linux-gnu` the `/etc/nixox/configuraqtion.nix`
entry would be `boot.binfmt.emulatedSystems = [ "riscv64-linux" ]`.
3. Propose the commit as a PR to update bootstrap tarballs, tag people
who can help you test the updated architecture and once reviewed tag
`@lovesegfault` to upload the tarballs.
## Bootstrap files job definitions
There are two types of bootstrap files:
- natively built `stdenvBootstrapTools.build` hydra jobs in
[`nixpkgs:trunk`](https://hydra.nixos.org/jobset/nixpkgs/trunk#tabs-jobs)
jobset. Incomplete list of examples is:
* `aarch64-unknown-linux-musl.nix`
* `i686-unknown-linux-gnu.nix`
These are Tier 1 hydra platforms.
- cross-built by `bootstrapTools.build` hydra jobs in
[`nixpkgs:cross-trunk`](https://hydra.nixos.org/jobset/nixpkgs/cross-trunk#tabs-jobs)
jobset. Incomplete list of examples is:
* `mips64el-unknown-linux-gnuabi64.nix`
* `mips64el-unknown-linux-gnuabin32.nix`
* `mipsel-unknown-linux-gnu.nix`
* `powerpc64le-unknown-linux-gnu.nix`
* `riscv64-unknown-linux-gnu.nix`
These are usually Tier 2 and lower targets.
The `.build` job contains `/on-server/` subdirectory with binaries to
be uploaded to `tarballs.nixos.org`.
The files are uploaded to `tarballs.nixos.org` by writers to `S3` store.
## TODOs
- `pkgs/stdenv/darwin` file layout is slightly different from
`pkgs/stdenv/linux`. Once `linux` seed update becomes a routine we can
bring `darwin` in sync if it's feasible.
- `darwin` definition of `.build` `on-server/` directory layout differs
and should be updated.