This adds a new `imageStream` option that can be used in conjunction
with `pkgs.dockerTools.streamLayeredImage` so that the image archive
never needs to be materialized in the `/nix/store`. This greatly
improves the disk utilization for systems that use container images
built using Nix because they only need to store image layers instead of
the full image. Additionally, when deploying the new system and only
new layers need to be built/copied.
Since version 2.0.0, proc-macro-crate has assumed it can exec()
`env::var("CARGO")` in order to run `cargo locate-project`.
This commit adds a crate override to proc-macro-crate which simply writes the
path to buildPlatform.cargo into the proc-macro-crate sources.
This way we don't need to set `env.CARGO` for every build that depends on
proc-macro-crate -- if we do that, the $CARGO environment variable would be
visible to the entire build. This could potentially lead to incredibly
hard-to-troubleshoot heisenbugs if there is some other crate that expects
`env::var("CARGO")` to exist -- that other crate would mysteriously work only
in projects that use proc-macro-crate but not anywhere else!
Fixes two bugs:
- pass a forgotten `{}` to `compressDrv`.
- remove incorrect usage of `lndir` in `compressDrv`. I added a brief
comment on why, see [this comment][1] for more details.
Tested with:
```
$ nix build .#legacyPackages.x86_64-linux.gitea.passthru.data-compressed
$ ls -lh result/public/assets/licenses.txt*
lrwxrwxrwx 1 root root 90 Jan 1 1970 result/public/assets/licenses.txt -> /nix/store/p21irsr57hckd3x3ym18aa0cr9zmm3an-gitea-1.22.1-data/./public/assets/licenses.txt
-r--r--r-- 1 root root 30K Jan 1 1970 result/public/assets/licenses.txt.br
-r--r--r-- 1 root root 82K Jan 1 1970 result/public/assets/licenses.txt.gz
```
[1]: https://github.com/NixOS/nixpkgs/pull/332752#discussion_r1721043286
String-interpolation converts path objects inside `contents` into store
paths to ensure they are properly included in the result image.
See tests.trivial-builders.references for the necessity of
string-interpolation.
Quote each string-interpolated content member to accomodates spaces
inside.
Was trying out the recommended example for `writePython3Bin` and it
failed with:
```
Traceback (most recent call last):
File "/nix/store/gcmhfm7mslpndjasfhvs66f1ca24vxim-test_py3/bin/test_py3", line 4, in <module>
y = yaml.load("""
TypeError: load() missing 1 required positional argument: 'Loader'
```
Looks like `yaml.load(input)` was deprecated in 5.1: https://msg.pyyaml.org/load
`nixos-24.05` uses `6.0.1` so we're in the clear.
Place the VM disk image in a local directory "disk-image" instead of
"$out", so that we don't have to delete it to reserve "$out" for the
container image.
