stockholm/krebs/3modules/git.nix

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{ config, lib, pkgs, ... }:
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# TODO unify logging of shell scripts to user and journal
# TODO move all scripts to ${etcDir}, so ControlMaster connections
# immediately pick up new authenticators
# TODO when authorized_keys changes, then restart ssh
# (or kill already connected users somehow)
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with import <stockholm/lib>;
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let
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cfg = config.krebs.git;
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out = {
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options.krebs.git = api;
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config = with lib; mkIf cfg.enable (mkMerge [
(mkIf cfg.cgit.enable cgit-imp)
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git-imp
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]);
};
api = {
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enable = mkEnableOption "krebs.git";
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cgit = mkOption {
type = types.submodule {
options = {
enable = mkEnableOption "krebs.git.cgit" // { default = true; };
fcgiwrap = {
group = mkOption {
type = types.group;
default = {
name = "fcgiwrap";
};
};
user = mkOption {
type = types.user;
default = {
name = "fcgiwrap";
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home = toString pkgs.emptyDirectory;
};
};
};
settings = mkOption {
apply = flip removeAttrs ["_module"];
default = {};
type = subtypes.cgit-settings;
};
};
};
default = {};
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description = ''
Cgit is an attempt to create a fast web interface for the git version
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control system, using a built in cache to decrease pressure on the
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git server.
cgit in this module is being served via fastcgi nginx.This module
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deploys a http://cgit.hostname nginx configuration and enables nginx
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if not yet enabled.
'';
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};
dataDir = mkOption {
type = types.str;
default = "/var/lib/git";
description = "Directory used to store repositories.";
};
etcDir = mkOption {
type = mkOptionType {
name = "${types.absolute-pathname.name} starting with `/etc/'";
check = x: types.absolute-pathname.check x && hasPrefix "/etc/" x;
merge = mergeOneOption;
};
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default = "/etc/git";
};
repos = mkOption {
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type = types.attrsOf subtypes.repo;
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default = {};
example = literalExample ''
{
testing = {
name = "testing";
hooks.post-update = '''
#! /bin/sh
set -euf
echo post-update hook: $* >&2
''';
};
testing2 = { name = "testing2"; };
}
'';
description = ''
Repositories.
'';
};
rules = mkOption {
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type = types.listOf subtypes.rule;
default = [];
example = literalExample ''
singleton {
user = [ config.krebs.users.tv ];
repo = [ testing ]; # see literal example of repos
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perm = push "refs/*" (with git; [
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non-fast-forward create delete merge
]);
}
'';
description = ''
access and permission rules for git repositories.
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'';
};
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user = mkOption {
type = types.user;
default = {
name = "git";
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home = toString pkgs.emptyDirectory;
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};
};
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};
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# TODO put into krebs/4lib/types.nix?
subtypes = {
cgit-settings = types.submodule {
# A setting's value of `null` means cgit's default should be used.
options = {
about-filter = mkOption {
type = types.nullOr types.package;
default = null;
};
cache-root = mkOption {
type = types.absolute-pathname;
default = "/tmp/cgit";
};
cache-size = mkOption {
type = types.uint;
default = 1000;
};
css = mkOption {
type = types.absolute-pathname;
default = "/static/cgit.css";
};
enable-commit-graph = mkOption {
type = types.bool;
default = true;
};
enable-index-links = mkOption {
type = types.bool;
default = true;
};
enable-index-owner = mkOption {
type = types.bool;
default = false;
};
enable-log-filecount = mkOption {
type = types.bool;
default = true;
};
enable-log-linecount = mkOption {
type = types.bool;
default = true;
};
enable-remote-branches = mkOption {
type = types.bool;
default = true;
};
logo = mkOption {
type = types.absolute-pathname;
default = "/static/cgit.png";
};
max-stats = mkOption {
type =
types.nullOr (types.enum ["week" "month" "quarter" "year"]);
default = "year";
};
readme = mkOption {
type = types.listOf types.str;
default = [];
};
robots = mkOption {
type = types.nullOr (types.listOf types.str);
default = ["nofollow" "noindex"];
};
root-desc = mkOption {
type = types.nullOr types.str;
default = null;
};
root-title = mkOption {
type = types.nullOr types.str;
default = null;
};
source-filter = mkOption {
type = types.nullOr types.absolute-pathname;
default = null;
example = literalExample
"\${pkgs.cgit}/lib/cgit/filters/syntax-highlighting.py";
};
virtual-root = mkOption {
type = types.nullOr types.absolute-pathname;
default = "/";
};
};
};
repo = types.submodule ({ config, ... }: {
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options = {
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admins = mkOption {
type = types.listOf types.user;
default = [];
description = ''
List of users that should be able to do everything with this repo.
This option is currently not used by krebs.git but instead can be
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used to create rules. See e.g. stockholm/lass/2configs/git.nix for
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an example.
'';
};
cgit = {
desc = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
Repository description.
'';
};
path = mkOption {
type = types.str;
default = "${cfg.dataDir}/${config.name}";
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defaultText = "${cfg.dataDir}/reponame";
description = ''
An absolute path to the repository directory. For non-bare
repositories this is the .git-directory.
'';
};
section = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
Repository section.
'';
};
url = mkOption {
type = types.str;
default = config.name;
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defaultText = "reponame";
description = ''
The relative url used to access the repository.
'';
};
};
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collaborators = mkOption {
type = types.listOf types.user;
default = [];
description = ''
List of users that should be able to fetch from this repo.
This option is currently not used by krebs.git but instead can be
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used to create rules. See e.g. stockholm/tv/2configs/git.nix for
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an example.
'';
};
name = mkOption {
type = types.str;
description = ''
Repository name.
'';
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defaultText = "reponame";
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};
hooks = mkOption {
type = types.attrsOf types.str;
default = {};
description = ''
Repository-specific hooks.
'';
};
public = mkOption {
type = types.bool;
default = false;
description = ''
Allow everybody to read the repository via HTTP if cgit enabled.
'';
# TODO allow every configured user to fetch the repository via SSH.
};
};
});
rule = types.submodule ({ config, ... }: {
options = {
user = mkOption {
type = types.listOf types.user;
description = ''
List of users this rule should apply to.
Checked by authorize-command.
'';
};
repo = mkOption {
type = types.listOf subtypes.repo;
description = ''
List of repos this rule should apply to.
Checked by authorize-command.
'';
};
perm = mkOption {
type = types.submodule {
# TODO generate enum argument from krebs/4lib/git.nix
options = {
allow-commands = mkOption {
type = types.listOf (types.enum (with git; [
git-receive-pack
git-upload-pack
]));
default = [];
description = ''
List of commands the rule's users are allowed to execute.
Checked by authorize-command.
'';
};
allow-receive-ref = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
Ref that can receive objects.
Checked by authorize-push.
'';
};
allow-receive-modes = mkOption {
type = types.listOf (types.enum (with git; [
fast-forward
non-fast-forward
create
delete
merge
]));
default = [];
description = ''
List of allowed receive modes.
Checked by pre-receive hook.
'';
};
};
};
description = ''
Permissions granted.
'';
};
};
});
};
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git-imp = {
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system.activationScripts.git-init = "${init-script}";
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# TODO maybe put all scripts here and then use PATH?
environment.etc.${removePrefix "/etc/" cfg.etcDir}.source =
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scriptFarm "git-ssh-authorizers" {
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authorize-command = makeAuthorizeScript (map (rule: [
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(map getName (toList rule.user))
(map getName (toList rule.repo))
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(map getName rule.perm.allow-commands)
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]) cfg.rules);
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authorize-push = makeAuthorizeScript (map (rule: [
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(map getName (toList rule.user))
(map getName (toList rule.repo))
(toList rule.perm.allow-receive-ref)
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(map getName rule.perm.allow-receive-modes)
]) (filter (rule: rule.perm.allow-receive-ref != null) cfg.rules));
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};
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users.users.${cfg.user.name} = {
inherit (cfg.user) home name uid;
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description = "Git repository hosting user";
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# To allow running cgit-clear-cache via hooks.
group = cfg.cgit.fcgiwrap.group.name;
isSystemUser = true;
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shell = "/bin/sh";
openssh.authorizedKeys.keys =
unique
(sort lessThan
(map (makeAuthorizedKey git-ssh-command)
(filter (user: isString user.pubkey)
(concatMap (getAttr "user") cfg.rules))));
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};
};
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cgit-imp = {
users = {
groups.${cfg.cgit.fcgiwrap.group.name} = {
inherit (cfg.cgit.fcgiwrap.group) name gid;
};
users.${cfg.cgit.fcgiwrap.user.name} = {
inherit (cfg.cgit.fcgiwrap.user) home name uid;
group = cfg.cgit.fcgiwrap.group.name;
isSystemUser = true;
};
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};
services.fcgiwrap = {
enable = true;
user = cfg.cgit.fcgiwrap.user.name;
group = cfg.cgit.fcgiwrap.group.name;
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# socketAddress = "/run/fcgiwrap.sock" (default)
# socketType = "unix" (default)
};
environment.etc."cgitrc".text = let
repo-to-cgitrc = _: repo:
optionals (isPublicRepo repo) (concatLists [
[""] # empty line
[(kv-to-cgitrc "repo.url" repo.cgit.url)]
(mapAttrsToList kv-to-cgitrc
(mapAttrs' (k: nameValuePair "repo.${k}")
(removeAttrs repo.cgit ["url"])))
]);
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kv-to-cgitrc = k: v: getAttr (typeOf v) {
bool = kv-to-cgitrc k (if v then 1 else 0);
null = []; # This will be removed by `flatten`.
list = {
readme = map (x: "readme=${x}") v;
}.${k} or "${k}=${concatStringsSep ", " v}";
int = "${k}=${toString v}";
set =
if subtypes.cgit-settings.check v
then "${k}=${v}"
else error "kv-to-cgitrc: unhandled type: set";
string = "${k}=${v}";
};
in
concatStringsSep "\n"
(flatten (
mapAttrsToList kv-to-cgitrc cfg.cgit.settings
++
mapAttrsToList repo-to-cgitrc cfg.repos
));
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environment.systemPackages = [
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(pkgs.cgit-clear-cache.override { inherit (cfg.cgit.settings) cache-root; })
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];
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system.activationScripts.cgit = ''
mkdir -m 0770 -p ${cfg.cgit.settings.cache-root}
chmod 0770 ${cfg.cgit.settings.cache-root}
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chown ${toString cfg.cgit.fcgiwrap.user.name}:${toString cfg.cgit.fcgiwrap.group.name} ${cfg.cgit.settings.cache-root}
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'';
services.nginx.virtualHosts.cgit = {
serverAliases = [
"cgit.${config.networking.hostName}"
"cgit.${config.networking.hostName}.r"
];
locations."/".extraConfig = ''
include ${pkgs.nginx}/conf/fastcgi_params;
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fastcgi_param SCRIPT_FILENAME ${pkgs.writeDash "cgit-wrapper" ''
set -efu
exec 3>&1
${pkgs.cgit}/cgit/cgit.cgi "$@" 2>&1 >&3 3>&- \
| ${pkgs.gnused}/bin/sed \
'
\|^${pkgs.cgit}/cgit/cgit.cgi: Relink |d
'
exec 3>&-
''};
fastcgi_param PATH_INFO $uri;
fastcgi_param QUERY_STRING $args;
fastcgi_param HTTP_HOST $server_name;
fastcgi_pass unix:${config.services.fcgiwrap.socketAddress};
'';
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# Smart HTTP transport. Regex based on.
# https://github.com/git/git/blob/v2.27.0/http-backend.c#L708-L721
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locations."~ \"^/[0-9A-Za-z._-]+/(HEAD|info/refs|objects/info/(alternates|http-alternates|packs)|[0-9a-f]{2}/([0-9a-f]{38}|[0-9a-f]{62})|pack/pack-([0-9a-f]{40}|[0-9a-f]{64})\\.(pack|idx)|git-upload-pack|git-receive-pack)$\"".extraConfig = ''
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include ${pkgs.nginx}/conf/fastcgi_params;
fastcgi_param GIT_HTTP_EXPORT_ALL "";
fastcgi_param GIT_PROJECT_ROOT ${cfg.dataDir};
fastcgi_param PATH_INFO $fastcgi_script_name;
fastcgi_param SCRIPT_FILENAME ${pkgs.git}/bin/git-http-backend;
fastcgi_pass unix:${config.services.fcgiwrap.socketAddress};
'';
locations."/static/".extraConfig = ''
root ${pkgs.cgit}/cgit;
rewrite ^/static(/.*)$ $1 break;
'';
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};
};
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getName = x: x.name;
isPublicRepo = getAttr "public"; # TODO this is also in ./cgit.nix
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makeAuthorizedKey = git-ssh-command: user@{ name, pubkey, ... }:
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# TODO assert name
# TODO assert pubkey
let
options = concatStringsSep "," [
''command="exec ${git-ssh-command} ${name}"''
"no-agent-forwarding"
"no-port-forwarding"
"no-pty"
"no-X11-forwarding"
];
in
"${options} ${pubkey}";
# [case-pattern] -> shell-script
# Create a shell script that succeeds (exit 0) when all its arguments
# match the case patterns (in the given order).
makeAuthorizeScript =
let
# TODO escape
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to-pattern = x: concatStringsSep "|" (toList x);
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go = i: ps:
if ps == []
then "exit 0"
else ''
case ''$${toString i} in ${to-pattern (head ps)})
${go (i + 1) (tail ps)}
esac'';
in
patterns: ''
#! /bin/sh
set -euf
${concatStringsSep "\n" (map (go 1) patterns)}
exit -1
'';
reponames = rules: sort lessThan (unique (map (x: x.repo.name) rules));
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# TODO use pkgs.write (from nix-writers)
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scriptFarm =
farm-name: scripts:
let
makeScript = script-name: script-string: {
name = script-name;
path = pkgs.writeScript "${farm-name}_${script-name}" script-string;
};
in
pkgs.linkFarm farm-name (mapAttrsToList makeScript scripts);
git-ssh-command = pkgs.writeScript "git-ssh-command" ''
#! /bin/sh
set -euf
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PATH=${makeBinPath (with pkgs; [
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coreutils
git
gnugrep
gnused
systemd
])}
abort() {
echo "error: $1" >&2
systemd-cat -p err -t git echo "error: $1"
exit -1
}
GIT_SSH_USER=$1
systemd-cat -p info -t git echo \
"authorizing $GIT_SSH_USER $SSH_CONNECTION $SSH_ORIGINAL_COMMAND"
# References: The Base Definitions volume of
# POSIX.12013, Section 3.278, Portable Filename Character Set
portable_filename_bre="^[A-Za-z0-9._-]\\+$"
command=$(echo "$SSH_ORIGINAL_COMMAND" \
| sed -n 's/^\([^ ]*\) '"'"'\(.*\)'"'"'/\1/p' \
| grep "$portable_filename_bre" \
|| abort 'cannot read command')
GIT_SSH_REPO=$(echo "$SSH_ORIGINAL_COMMAND" \
| sed -n 's/^\([^ ]*\) '"'"'\(.*\)'"'"'/\2/p' \
| grep "$portable_filename_bre" \
|| abort 'cannot read reponame')
${cfg.etcDir}/authorize-command \
"$GIT_SSH_USER" "$GIT_SSH_REPO" "$command" \
|| abort 'access denied'
repodir=${escapeShellArg cfg.dataDir}/$GIT_SSH_REPO
systemd-cat -p info -t git \
echo "authorized exec $command $repodir"
export GIT_SSH_USER
export GIT_SSH_REPO
exec "$command" "$repodir"
'';
init-script = pkgs.writeScript "git-init" ''
#! /bin/sh
set -euf
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PATH=${makeBinPath (with pkgs; [
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coreutils
findutils
gawk
git
gnugrep
gnused
])}
dataDir=${escapeShellArg cfg.dataDir}
mkdir -p "$dataDir"
# Notice how the presence of hooks symlinks determine whether
# we manage a repositry or not.
# Make sure that no existing repository has hooks. We can delete
# symlinks because we assume we created them.
find "$dataDir" -mindepth 2 -maxdepth 2 -name hooks -type l -delete
bad_hooks=$(find "$dataDir" -mindepth 2 -maxdepth 2 -name hooks)
if echo "$bad_hooks" | grep -q .; then
printf 'error: unknown hooks:\n%s\n' \
"$(echo "$bad_hooks" | sed 's/^/ /')" \
>&2
exit -1
fi
# Initialize repositories.
${concatMapStringsSep "\n" (repo:
let
hooks = scriptFarm "git-hooks" (makeHooks repo);
in
''
reponame=${escapeShellArg repo.name}
repodir=$dataDir/$reponame
mode=${toString (if isPublicRepo repo then 0711 else 0700)}
if ! test -d "$repodir"; then
mkdir -m "$mode" "$repodir"
git init --bare --template=/var/empty "$repodir"
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# TODO fix correctly with stringAfter
chown -R ${toString config.users.users.git.uid}:nogroup "$repodir"
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fi
ln -Tfs ${hooks} "$repodir/hooks"
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''
) (attrValues cfg.repos)}
# Warn about repositories that exist but aren't mentioned in the
# current configuration (and thus didn't receive a hooks symlink).
unknown_repos=$(find "$dataDir" -mindepth 1 -maxdepth 1 \
-type d \! -exec test -e '{}/hooks' \; -print)
if echo "$unknown_repos" | grep -q .; then
printf 'warning: stale repositories:\n%s\n' \
"$(echo "$unknown_repos" | sed 's/^/ /')" \
>&2
fi
'';
makeHooks = repo: removeAttrs repo.hooks [ "pre-receive" ] // {
pre-receive = ''
#! /bin/sh
set -euf
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PATH=${makeBinPath (with pkgs; [
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coreutils # env
git
systemd
])}
accept() {
#systemd-cat -p info -t git echo "authorized $1"
accept_string="''${accept_string+$accept_string
}authorized $1"
}
reject() {
#systemd-cat -p err -t git echo "denied $1"
#echo 'access denied' >&2
#exit_code=-1
reject_string="''${reject_string+$reject_string
}access denied: $1"
}
empty=0000000000000000000000000000000000000000
accept_string=
reject_string=
while read oldrev newrev ref; do
if [ $oldrev = $empty ]; then
receive_mode=create
elif [ $newrev = $empty ]; then
receive_mode=delete
elif [ "$(git merge-base $oldrev $newrev)" = $oldrev ]; then
receive_mode=fast-forward
else
receive_mode=non-fast-forward
fi
if ${cfg.etcDir}/authorize-push \
"$GIT_SSH_USER" "$GIT_SSH_REPO" "$ref" "$receive_mode"; then
accept "$receive_mode $ref"
else
reject "$receive_mode $ref"
fi
done
if [ -n "$reject_string" ]; then
systemd-cat -p err -t git echo "$reject_string"
exit -1
fi
systemd-cat -p info -t git echo "$accept_string"
${optionalString (hasAttr "post-receive" repo.hooks) ''
# custom post-receive hook
${repo.hooks.post-receive}''}
'';
};
in
out