686fc14 · nix-container

git.iko.soy/nix-container

Auto-add the host shell package so container.nix needn't list it

commit686fc14a9879b2c0f433f440c4b7d38ed0e408a3 authoriko <mail@iko.soy> dateSat 27 Jun 2026, 21:40 (3 months ago) parentbd3aac1

3 files changed+22−12

compare with master

unifiedsplit

README.md+2−1 c+8−8 flake.nix+12−3

README.md+2−1

@@ -32,7 +32,6 @@ is **required**; there is no default set.

3232```nix

3333# ./container.nix

3434{ pkgs, nur }: with pkgs; [

35− fish # `init` runs your host shell — include it (here, fish)

3635 coreutils

3736 git

3837 go

@@ -40,6 +39,8 @@ is **required**; there is no default set.

4039]

4140```

4241

42+Your host shell (`$SHELL`) is added and run automatically — no need to list it.

43+

4344Point at a different file with `-c`/`--config`:

4445

4546```sh

c+8−8

@@ -27,12 +27,17 @@ switch $argv[1]

2727 exit 1

2828 end

2929

30− # Build an image with exactly the packages from $config, into a temp

31− # dir, load it, then clean up.

30+ # Host login shell (by name): run as the container cmd and added to the

31+ # image automatically, so it needn't be listed in container.nix.

32+ set -l shell fish

33+ test -n "$SHELL"; and set shell (path basename $SHELL)

34+

35+ # Build an image with the packages from $config (plus the shell) into a

36+ # temp dir, load it, then clean up.

3237 set -l tmp (mktemp -d)

3338 set -l archive $tmp/image.tar.gz

3439 set -lx NIX_CONTAINER_PKGS (path resolve $config)

35− set -l expr "(builtins.getFlake \"$flake\").lib.\${builtins.currentSystem}.copyWith (import (/. + builtins.getEnv \"NIX_CONTAINER_PKGS\"))"

40+ set -l expr "(builtins.getFlake \"$flake\").lib.\${builtins.currentSystem}.copyWithShell \"$shell\" (import (/. + builtins.getEnv \"NIX_CONTAINER_PKGS\"))"

3641 set -l copyer (nix build --impure --no-link --print-out-paths --expr "$expr")

3742 set -l rc $status

3843 if test $rc -eq 0

@@ -51,11 +56,6 @@ switch $argv[1]

5156 set -l mounts -v "$PWD:/workspace"

5257 test -d $HOME/.config; and set -a mounts -v "$HOME/.config:/root/.config"

5358

54− # Run the host's login shell (by name) instead of the image's default

55− # cmd. The shell must be in the package set.

56− set -l shell fish

57− test -n "$SHELL"; and set shell (path basename $SHELL)

58−

5959 # Replace any existing container of the same name.

6060 container rm --force $name 2>/dev/null

6161 container create --name $name --ssh -it --cwd /workspace $mounts $argv $image /bin/$shell

flake.nix+12−3

@@ -77,9 +77,9 @@

7777 imageTag = "latest";

7878

7979 # Build the OCI image from a `{ pkgs, nur }: [ ... ]` package function.

80− # The default `cmd` is /bin/fish, but `c init` runs your host login

81− # shell instead — so include that shell in the package set (a missing

82− # shell is warned about below).

80+ # The default `cmd` is /bin/fish; `c init` runs your host login shell

81+ # instead and adds it automatically (see `copyWithShell`). The warning

82+ # below only catches an image left with no shell at all.

8383 mkImage =

8484 packages:

8585 let

@@ -153,6 +153,15 @@

153153 # skopeo copy app (`skopeo copy nix:<image> "$@"`) for an image built

154154 # from a `{ pkgs, nur }: [ ... ]` function.

155155 copyWith = packages: (mkImage packages).copyTo;

156+ # Like `copyWith`, but also adds the named shell package (when it

157+ # exists in nixpkgs) so `c init` can run the host shell without it

158+ # being listed in `container.nix`.

159+ copyWithShell =

160+ shell: packages:

161+ (mkImage (

162+ { pkgs, nur }:

163+ packages { inherit pkgs nur; } ++ pkgs.lib.optional (pkgs ? ${shell}) pkgs.${shell}

164+ )).copyTo;

156165 };

157166 }

158167 );