master..c7f802a · nix-container

git.iko.soy/nix-container

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README.md+26−35

since splitsnapshots

unifiedsplit

@@ -5,10 +5,8 @@ A Nix flake that builds an **OCI image** (via

5Apple's [`container`](https://github.com/apple/container) CLI on macOS.

7It's a plain, single-process image — no NixOS, no systemd — defined in

8−[`flake.nix`](./flake.nix). `c start` drops you into a

8+[`flake.nix`](./flake.nix). It runs `fish` by default (with a configured

9−[`herdr`](https://herdr.dev) session whose panes use your host login shell

10−(detected and bundled by `c init`). You choose what else it ships via a

11−per-project `container.nix`.

9+prompt); you choose what else it ships via a per-project `container.nix`.

13## Prerequisites

11## Prerequisites

@@ -27,31 +25,24 @@ per-project `container.nix`.

28## Packages

26## Packages

30−`init` builds the image from a **`container.nix`** in the current directory — an

28+`init` builds the image from a **`container.nix`** in the current directory — a

31−attrset with a `packages` function (`{ pkgs, nur }` returning the package list;

29+`{ pkgs, nur }` function returning the package list (`nur` is

32−`nur` is [NUR](https://github.com/nix-community/NUR), for packages outside

30+[NUR](https://github.com/nix-community/NUR), for packages outside nixpkgs). It

33−nixpkgs) and an optional `mounts` list. It is **required**; there is no default.

31+is **required**; there is no default set.

35```nix

33```nix

36# ./container.nix

34# ./container.nix

37−{

38− packages = { pkgs, nur }: with pkgs; [

35+{ pkgs, nur }: with pkgs; [

36+ coreutils

39− git

37+ git

40− go

38+ go

41− nur.repos.charmbracelet.crush

39+ nur.repos.charmbracelet.crush

42− ];

43− # Extra "host:container" bind mounts, on top of $PWD → /workspace. A leading

44− # ~/ in the host path expands to $HOME. Optional.

45− mounts = [

46− "~/data:/data"

47− ];

40+]

48−}

49```

41```

51−Your **host login shell** (detected by `c init`, bash fallback), **coreutils**,

43+**fish** (the default command, with a configured prompt) and **Nix** itself

52−[**herdr**](https://herdr.dev) (the session `c start` launches), **Nix** itself

53−(with CA certs and `nix-command`/`flakes` enabled, single-user), and the ncurses

44+(with CA certs and `nix-command`/`flakes` enabled, single-user) are always

54−**terminfo** database are always included — no need to list them.

45+included — no need to list them.

56Point at a different file with `-c`/`--config`:

47Point at a different file with `-c`/`--config`:

@@ -68,17 +59,18 @@ that holds a `container.nix`; the container is named after that directory.

68# build the image, load it, and create the container (named after $PWD):

59# build the image, load it, and create the container (named after $PWD):

69nix run github:ilyakooo0/nix-container -- init

60nix run github:ilyakooo0/nix-container -- init

71−# start it and attach — drops you into a herdr session:

62+# start it and attach — drops you into fish:

72nix run github:ilyakooo0/nix-container -- start

63nix run github:ilyakooo0/nix-container -- start

73```

64```

75- `init` builds the OCI archive in a temp dir, loads it into `container`,

66- `init` builds the OCI archive in a temp dir, loads it into `container`,

76 deletes the temp file, then (re)creates the container. It mounts the current

67 deletes the temp file, then (re)creates the container. It mounts the current

77− directory at `/workspace` (the container's working directory).

68+ directory at `/workspace` (the container's working directory) and your

69+ `~/.config` at `/root/.config` (fish runs with `--no-config`, so this won't

70+ override its bundled prompt; other tools still read it).

78- `--ssh` forwards your host SSH agent socket into the container (so `git` over

71- `--ssh` forwards your host SSH agent socket into the container (so `git` over

79 SSH works with your keys).

72 SSH works with your keys).

80−- Add more mounts persistently via `mounts` in `container.nix` (above), or

81− ad-hoc by passing them through to `create` (mounts can only be set at creation):

73+- Add more mounts by passing them through (mounts can only be set at creation):

83 ```sh

75 ```sh

84 nix run github:ilyakooo0/nix-container -- init -v $HOME/data:/data

76 nix run github:ilyakooo0/nix-container -- init -v $HOME/data:/data

@@ -99,19 +91,18 @@ nix run github:ilyakooo0/nix-container -- init

99## Customize further

91## Customize further

100

101Fork or clone to change what isn't per-project — `config.cmd`/`env` or the image

93Fork or clone to change what isn't per-project — `config.cmd`/`env` or the image

102−name — in [`flake.nix`](./flake.nix). The flake also exposes build helpers:

94+name — in [`flake.nix`](./flake.nix). The flake also exposes build helpers, both

95+taking a `{ pkgs, nur }: [ ... ]` function:

103

97+- `lib.<system>.mkImage` → an OCI image.

104−- `lib.<system>.copyWith` → a skopeo copy app for a `{ pkgs, nur }: [ ... ]`

98+- `lib.<system>.copyWith` → a skopeo copy app, for building/pushing the image

105− function, for building/pushing the image anywhere skopeo can write (e.g. a

99+ anywhere skopeo can write (e.g. a registry):

106− registry):

107

100

108 ```sh

101 ```sh

109 drv=$(nix build --no-link --print-out-paths --impure --expr \

102 drv=$(nix build --no-link --print-out-paths --impure --expr \

110− '(builtins.getFlake "github:ilyakooo0/nix-container").lib.${builtins.currentSystem}.copyWith (import ./container.nix).packages')

103+ '(builtins.getFlake "github:ilyakooo0/nix-container").lib.${builtins.currentSystem}.copyWith (import ./container.nix)')

111 $drv/bin/copy-to docker://ghcr.io/me/img:latest

104 $drv/bin/copy-to docker://ghcr.io/me/img:latest

112 ```

105 ```

113−- `lib.<system>.mkImage <name> <shell>` → the underlying OCI image (`copyWith`

114− defaults these to `nix-container` / `bash`).

115

106

116The flake uses `flake-utils` over `{aarch64,x86_64}-{darwin,linux}`; the host

107The flake uses `flake-utils` over `{aarch64,x86_64}-{darwin,linux}`; the host

117system maps to the matching Linux target automatically (an Intel Mac builds an

108system maps to the matching Linux target automatically (an Intel Mac builds an

c+13−43

@@ -1,7 +1,7 @@

1#!/usr/bin/env fish

2# Manage a container named after the current directory.

3# c init [-c FILE] [extra create args] build + load the image, then (re)create it

4−# (config from FILE, default ./container.nix)

4+# (packages from FILE, default ./container.nix)

5# c start start it and attach

7set -l name (path basename $PWD)

@@ -22,23 +22,17 @@ switch $argv[1]

22 end

24 if not test -e $config

25− echo "c: config file not found: $config" >&2

25+ echo "c: package file not found: $config" >&2

26− echo " create one ('{ packages = { pkgs, nur }: [ ... ]; mounts = [ ]; }') or pass -c FILE" >&2

26+ echo " create one ('{ pkgs, nur }: [ ... ]') or pass -c FILE" >&2

27 exit 1

28 end

30− # Host login shell (by name): added to the image automatically and baked

31− # in as the cmd + default $SHELL (what herdr panes etc. spawn), so it

32− # needn't be listed in container.nix. Falls back to bash.

33− set -l shell bash

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

35−

36− # Build an image with the config's `packages` (plus the shell) into a

30+ # Build an image with the packages from $config into a temp dir, load

37− # temp dir, load it, then clean up.

31+ # it, then clean up.

38 set -l tmp (mktemp -d)

32 set -l tmp (mktemp -d)

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

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

40− set -lx NIX_CONTAINER_CONFIG (path resolve $config)

34+ set -lx NIX_CONTAINER_PKGS (path resolve $config)

41− set -l expr "(builtins.getFlake \"$flake\").lib.\${builtins.currentSystem}.copyWithShell \"nix-container-$name\" \"$shell\" (import (/. + builtins.getEnv \"NIX_CONTAINER_CONFIG\")).packages"

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

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

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

43 set -l rc $status

37 set -l rc $status

44 if test $rc -eq 0

38 if test $rc -eq 0

@@ -53,40 +47,16 @@ switch $argv[1]

53 rm -rf $tmp

47 rm -rf $tmp

54 test $rc -eq 0; or exit $rc

48 test $rc -eq 0; or exit $rc

56− # Mount the project at /workspace (the default cwd), plus any extra

50+ # Mount the project at /workspace (the default cwd) and host ~/.config.

57− # mounts from the config (`mounts = [ "host:container" … ]`). A leading

51+ # (fish runs with --no-config, so the mount can't shadow the prompt.)

58− # ~/ in the host path expands to $HOME (nix leaves it literal).

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

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

60− for m in (nix eval --impure --raw --expr "builtins.concatStringsSep \"\n\" ((import (/. + builtins.getEnv \"NIX_CONTAINER_CONFIG\")).mounts or [])")

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

61− set -a mounts -v (string replace -r '^~/' "$HOME/" -- $m)

62− end

63−

64− # TERM to bake into the container env (`-e TERM`): the runtime hands the

65− # `start -ai` session a bare "xterm", so set the host's real terminal,

66− # mapped to an entry the bundled ncurses ships — Ghostty reports

67− # "xterm-ghostty", which ncurses ships as "ghostty" — falling back to

68− # xterm-256color for an empty or bare-"xterm" value.

69− set -l term xterm-256color

70− if test "$TERM" = xterm-ghostty

71− set term ghostty

72− else if test -n "$TERM"; and test "$TERM" != xterm

73− set term $TERM

74− end

76− # Replace any existing container of the same name, then create it running

55+ # Replace any existing container of the same name. The image's cmd is

77− # herdr in a session named after the project (`<dir>-container`). This

56+ # /bin/fish, so no command is passed.

78− # overrides the image's default plain-herdr cmd; `c start` attaches to it.

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

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

80− # The image only lays down /bin and /etc, so /tmp and /run don't exist;

81− # without them anything that writes temp files (herdr, build tools, …)

82− # fails with ENOENT. Mount writable tmpfs at both.

83− container create --name $name --ssh -it -e "TERM=$term" \

58+ container create --name $name --ssh -it --cpus 8 --memory 8g --cwd /workspace $mounts $argv $image

84− --tmpfs /tmp --tmpfs /run --memory 8g --cwd /workspace $mounts $argv \

85− $image /bin/herdr session attach "$name-container"

86 case start

59 case start

87− # Start the container and attach to its cmd (herdr). TERM was baked into

88− # the container env at create time (`-e TERM`), which survives this path.

89− # Exiting herdr (PID1) stops the container; `c start` boots it again.

90 container start -ai $name

60 container start -ai $name

91 case '*'

61 case '*'

92 echo "usage: c init [-c FILE] [create args] | start" >&2

62 echo "usage: c init [-c FILE] [create args] | start" >&2

flake.nix+65−50

@@ -72,22 +72,53 @@

72 # Host package set, for the wrapper app below.

73 pkgsHost = nixpkgs.legacyPackages.${system};

75− # Default image name (for `copyWith`); `c init` passes a per-directory

75+ # Name/tag baked into the image's OCI config.

76− # name (`nix-container-<dir>`) to `copyWithShell` instead.

77 imageName = "nix-container";

76 imageName = "nix-container";

78 imageTag = "latest";

77 imageTag = "latest";

79+ # Fish prompt config. Installed at /etc/fish/prompt.fish and loaded via

80+ # `fish --no-config --init-command` (see `cmd` below), NOT from

81+ # $HOME/.config/fish — so the `~/.config` mount can't shadow it. Built

82+ # on the host arch (just a text file), so no Linux builder is needed.

83+ fishConfig = pkgsHost.writeText "prompt.fish" ''

84+ # No welcome banner.

85+ set -g fish_greeting

86+

87+ # Define the prompt as a function so fish renders it before every

88+ # command; at top level it would run once at startup and be ignored.

89+ function fish_prompt

90+ set -l nix_shell_info

91+ if set -q IN_NIX_SHELL; or set -q IN_NIX_RUN

92+ set nix_shell_info ' ❄️'

93+ end

94+

95+ set -l cwd (prompt_pwd)

96+

97+ set -l bookmark_info

98+ if jj root 2>/dev/null >/dev/null

99+ set -l jj_bookmark (jj log -r 'heads(::@ & bookmarks())' -T 'local_bookmarks ++ "\n"' --no-graph 2>/dev/null | tail -1)

100+ if test -n "$jj_bookmark"

101+ set bookmark_info ' ' (set_color brmagenta) $jj_bookmark (set_color normal)

102+ end

103+ end

104+

105+ echo -n -s (set_color $fish_color_cwd) $cwd (set_color normal) $bookmark_info ' 🏗️' $nix_shell_info '> '

106+ end

107+ '';

108+

109+ # Lay the prompt out at the path the cmd sources.

110+ fishRoot = pkgsHost.runCommand "fish-prompt" { } ''

111+ mkdir -p "$out/etc/fish"

112+ cp ${fishConfig} "$out/etc/fish/prompt.fish"

113+ '';

114+

80− # Build the OCI image (named `name`) from a `{ pkgs, nur }: [ ... ]`

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

81− # package function, for the named shell. The image's `cmd` is herdr

116+ # The image always runs /bin/fish; fish, its prompt config, and Nix are

82− # (the session `c start` attaches to); the shell is the default `$SHELL`

83− # (what herdr panes spawn) and is added automatically, so `container.nix`

117+ # bundled automatically, so `container.nix` lists only your extras.

84− # lists only your extras. Nix (+ CA certs) and the ncurses terminfo

85− # database are always shipped too. Nothing here is fish-specific: the

86− # TERM fixup happens host-side in `c` (passed via `-e TERM` at create).

87 mkImage =

118 mkImage =

88− name: shell: packages:

119+ packages:

89 n2c.buildImage {

120 n2c.buildImage {

90− inherit name;

121+ name = imageName;

91 tag = imageTag;

122 tag = imageTag;

92 inherit arch;

123 inherit arch;

124

@@ -95,6 +126,10 @@

95 # buildEnv only *symlinks* paths (never runs them), so build it on

126 # buildEnv only *symlinks* paths (never runs them), so build it on

96 # the host arch — the tree is arch-neutral and links the

127 # the host arch — the tree is arch-neutral and links the

97 # (substituted) Linux store paths, sparing the Linux builder.

128 # (substituted) Linux store paths, sparing the Linux builder.

129+ #

130+ # Always shipped: fish (the cmd) + its prompt, and Nix (+ CA certs)

131+ # so every container can use Nix; `initializeNixDatabase` registers

132+ # the baked store.

98 copyToRoot = pkgsHost.buildEnv {

133 copyToRoot = pkgsHost.buildEnv {

99 name = "root";

134 name = "root";

100 paths =

135 paths =

@@ -102,27 +137,19 @@

102 pkgs = pkgsLinux;

137 pkgs = pkgsLinux;

103 nur = nurPkgs;

138 nur = nurPkgs;

104 }

139 }

105− # The shell (cmd + $SHELL), when it exists in nixpkgs.

106− ++ pkgsLinux.lib.optional (pkgsLinux ? ${shell}) pkgsLinux.${shell}

107 ++ [

140 ++ [

141+ pkgsLinux.fish

142+ fishRoot

108 pkgsLinux.nix

143 pkgsLinux.nix

109 pkgsLinux.cacert

144 pkgsLinux.cacert

110− # Basic userland (ls, cat, cp, sleep, …) so the container is

111− # usable out of the box and tools that shell out don't fail.

112− pkgsLinux.coreutils-full

113 # Networking glue glibc needs: /etc/nsswitch.conf (+passwd,

145 # Networking glue glibc needs: /etc/nsswitch.conf (+passwd,

114 # group) so DNS/host lookups resolve, and /etc/protocols,

146 # group) so DNS/host lookups resolve, and /etc/protocols,

115 # /etc/services. Without these, hostname resolution fails.

147 # /etc/services. Without these, hostname resolution fails.

116 pkgsLinux.fakeNss

148 pkgsLinux.fakeNss

117 pkgsLinux.iana-etc

149 pkgsLinux.iana-etc

118− # The terminfo database (+ tput/clear/reset) so TUIs find the

119− # entry for whatever TERM `c` passes in and render correctly.

120− pkgsLinux.ncurses

121− # The session `c start` always launches.

122− pkgsLinux.herdr

123 ];

150 ];

124 # Link all of /etc so the above files (nsswitch.conf, protocols,

151 # Link all of /etc so the above files (nsswitch.conf, protocols,

125− # services, passwd, group, ssl certs) are present.

152+ # services, passwd, group, ssl certs, fish prompt) are present.

126 pathsToLink = [

153 pathsToLink = [

127 "/bin"

154 "/bin"

128 "/etc"

155 "/etc"

@@ -133,25 +160,20 @@

133

160

134 config = {

161 config = {

135 # `cmd` (not `entrypoint`): the default command, *replaced* by any

162 # `cmd` (not `entrypoint`): the default command, *replaced* by any

136− # command passed to `container run/create`. Plain herdr here;

163+ # command passed to `container run/create`. `--no-config` skips

137− # `c init` overrides it with `herdr session attach <dir>-container` so

164+ # $HOME/.config/fish (so a mounted ~/.config can't override the

138− # the session is named per project. `c start` attaches via

165+ # prompt); `--init-command` loads the bundled prompt instead.

139− # `container start -ai`; exiting herdr (PID1) stops the container.

140− cmd = [ "/bin/herdr" ];

166+ cmd = [

167+ "/bin/fish"

168+ "--no-config"

169+ "--init-command"

170+ "source /etc/fish/prompt.fish"

171+ ];

141 env = [

172 env = [

142 "PATH=/bin"

173 "PATH=/bin"

143 "HOME=/root"

174 "HOME=/root"

144− # Default shell for tools that spawn one (herdr panes, etc.).

145− "SHELL=/bin/${shell}"

146 # Marker so shells/scripts can detect they're in here.

175 # Marker so shells/scripts can detect they're in here.

147 "NIX_CONTAINER=1"

176 "NIX_CONTAINER=1"

148− # Advertise truecolor for 24-bit-aware tools; `c` passes the

149− # resolved TERM via -e (the runtime would otherwise force xterm).

150− "COLORTERM=truecolor"

151− # A UTF-8 locale so tools handle multibyte/wide characters

152− # correctly. glibc ships C.UTF-8 built in, so this needs no

153− # locale-archive.

154− "LANG=C.UTF-8"

155 # CA trust for every TLS client (curl/git/…) and Nix.

177 # CA trust for every TLS client (curl/git/…) and Nix.

156 "SSL_CERT_FILE=/etc/ssl/certs/ca-bundle.crt"

178 "SSL_CERT_FILE=/etc/ssl/certs/ca-bundle.crt"

157 "NIX_SSL_CERT_FILE=/etc/ssl/certs/ca-bundle.crt"

179 "NIX_SSL_CERT_FILE=/etc/ssl/certs/ca-bundle.crt"

@@ -164,7 +186,7 @@

164

186

165 # `nix run . -- init|start` runs the bundled `c` manager script. Its

187 # `nix run . -- init|start` runs the bundled `c` manager script. Its

166 # `init` builds the image from the project's `container.nix` (via

188 # `init` builds the image from the project's `container.nix` (via

167− # `lib.copyWithShell`); the script finds the flake from its own (store)

189+ # `lib.copyWith`); the script finds the flake from its own (store)

168 # location, so this works from a checkout or straight from

190 # location, so this works from a checkout or straight from

169 # `nix run github:…/nix-container`.

191 # `nix run github:…/nix-container`.

170 cApp = pkgsHost.writeShellScriptBin "c" ''

192 cApp = pkgsHost.writeShellScriptBin "c" ''

@@ -177,22 +199,15 @@

177 default = flake-utils.lib.mkApp { drv = cApp; };

199 default = flake-utils.lib.mkApp { drv = cApp; };

178 };

200 };

179

201

180− # Build helpers take a `{ pkgs, nur }: [ ... ]` packages function (the

202+ # Build helpers. `c init` uses `copyWith` to honour a per-project

181− # `packages` attr of a project's `container.nix`). `c init` uses

203+ # `container.nix`:

182− # `copyWithShell` (host shell baked in); `copyWith` is the generic form:

183 # (builtins.getFlake "github:…/nix-container")

204 # (builtins.getFlake "github:…/nix-container")

184− # .lib.<system>.copyWith (import ./container.nix).packages

205+ # .lib.<system>.copyWith (import ./container.nix)

185 lib = {

206 lib = {

186 inherit mkImage;

207 inherit mkImage;

187− # Build the image's `copyTo` script (a skopeo-copy wrapper) from a

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

188− # `{ pkgs, nur }: [ ... ]` function, named `imageName`. Defaults the

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

189− # shell (cmd + $SHELL) to bash; use `copyWithShell` to pick another.

190− copyWith = packages: (mkImage imageName "bash" packages).copyTo;

210+ copyWith = packages: (mkImage packages).copyTo;

191− # Like `copyWith`, but for the given image `name` and shell — `c init`

192− # passes `nix-container-<dir>` and the host login shell, which is added

193− # to the image and used as cmd + $SHELL without being listed in

194− # `container.nix`.

195− copyWithShell = name: shell: packages: (mkImage name shell packages).copyTo;

196 };

211 };

197 }

212 }

198 );

213 );