stockholm/krebs/3modules/git.nix
2024-06-05 20:43:48 +02:00

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{ config, lib, pkgs, ... }:
# TODO unify logging of shell scripts to user and journal
# TODO move all scripts to ${etcDir}, so ControlMaster connections
# immediately pick up new authenticators
# TODO when authorized_keys changes, then restart ssh
# (or kill already connected users somehow)
with import ../../lib/pure.nix { inherit lib; };
let
cfg = config.krebs.git;
out = {
options.krebs.git = api;
config = with lib; lib.mkIf cfg.enable (mkMerge [
(lib.mkIf cfg.cgit.enable cgit-imp)
git-imp
]);
};
api = {
enable = mkEnableOption "krebs.git";
cgit = mkOption {
type = types.submodule {
options = {
enable = mkEnableOption "krebs.git.cgit" // { default = true; };
fcgiwrap = {
group = mkOption {
type = types.group;
default = {
name = "fcgiwrap";
};
};
user = mkOption {
type = types.user;
default = {
name = "fcgiwrap";
home = toString pkgs.emptyDirectory;
};
};
};
settings = mkOption {
apply = flip removeAttrs ["_module"];
default = {};
type = subtypes.cgit-settings;
};
};
};
default = {};
description = ''
Cgit is an attempt to create a fast web interface for the git version
control system, using a built in cache to decrease pressure on the
git server.
cgit in this module is being served via fastcgi nginx.This module
deploys a http://cgit.hostname nginx configuration and enables nginx
if not yet enabled.
'';
};
dataDir = mkOption {
type = types.str;
default = "/var/lib/git";
description = "Directory used to store repositories.";
};
etcDir = mkOption {
type = mkOptionType {
name = "${types.absolute-pathname.name} starting with `/etc/'";
check = x: types.absolute-pathname.check x && hasPrefix "/etc/" x;
merge = mergeOneOption;
};
default = "/etc/git";
};
repos = mkOption {
type = types.attrsOf subtypes.repo;
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 {
type = types.listOf subtypes.rule;
default = [];
example = literalExample ''
singleton {
user = [ config.krebs.users.tv ];
repo = [ testing ]; # see literal example of repos
perm = push "refs/*" (with git; [
non-fast-forward create delete merge
]);
}
'';
description = ''
access and permission rules for git repositories.
'';
};
user = mkOption {
type = types.user;
default = {
name = "git";
home = toString pkgs.emptyDirectory;
};
};
};
# 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, ... }: {
options = {
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
used to create rules. See e.g. stockholm/lass/2configs/git.nix for
an example.
'';
};
cgit = {
desc = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
Repository description.
'';
};
path = mkOption {
type = types.str;
default = "${cfg.dataDir}/${config.name}";
defaultText = "${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;
defaultText = "reponame";
description = ''
The relative url used to access the repository.
'';
};
};
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
used to create rules. See e.g. stockholm/tv/2configs/git.nix for
an example.
'';
};
name = mkOption {
type = types.str;
description = ''
Repository name.
'';
defaultText = "reponame";
};
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.
'';
};
};
});
};
git-imp = {
system.activationScripts.git-init = "${init-script}";
# TODO maybe put all scripts here and then use PATH?
environment.etc.${removePrefix "/etc/" cfg.etcDir}.source =
scriptFarm "git-ssh-authorizers" {
authorize-command = makeAuthorizeScript (map (rule: [
(map getName (toList rule.user))
(map getName (toList rule.repo))
(map getName rule.perm.allow-commands)
]) cfg.rules);
authorize-push = makeAuthorizeScript (map (rule: [
(map getName (toList rule.user))
(map getName (toList rule.repo))
(toList rule.perm.allow-receive-ref)
(map getName rule.perm.allow-receive-modes)
]) (filter (rule: rule.perm.allow-receive-ref != null) cfg.rules));
};
users.users.${cfg.user.name} = {
inherit (cfg.user) home name uid;
description = "Git repository hosting user";
# To allow running cgit-clear-cache via hooks.
group = cfg.cgit.fcgiwrap.group.name;
isSystemUser = true;
shell = "/bin/sh";
openssh.authorizedKeys.keys =
unique
(sort lessThan
(map (makeAuthorizedKey git-ssh-command)
(filter (user: isString user.pubkey)
(concatMap (getAttr "user") cfg.rules))));
};
users.groups.${cfg.cgit.fcgiwrap.group.name} = {};
};
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;
};
};
services.fcgiwrap = {
enable = true;
user = cfg.cgit.fcgiwrap.user.name;
group = cfg.cgit.fcgiwrap.group.name;
# 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.${k}")
(removeAttrs repo.cgit ["url"])))
]);
kv-to-cgitrc = k: v: getAttr (typeOf v) {
bool = kv-to-cgitrc k (if v then 1 else 0);
null = []; # This will be removed by `flatten`.
list = {
readme = map (x: "readme=${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
));
environment.systemPackages = [
(pkgs.cgit-clear-cache.override { inherit (cfg.cgit.settings) cache-root; })
];
system.activationScripts.cgit = ''
mkdir -m 0770 -p ${cfg.cgit.settings.cache-root}
chmod 0770 ${cfg.cgit.settings.cache-root}
chown ${toString cfg.cgit.fcgiwrap.user.name}:${toString cfg.cgit.fcgiwrap.group.name} ${cfg.cgit.settings.cache-root}
'';
services.nginx.virtualHosts.cgit = {
serverAliases = [
"cgit.${config.networking.hostName}"
"cgit.${config.networking.hostName}.r"
];
locations."/".extraConfig = ''
include ${pkgs.nginx}/conf/fastcgi_params;
fastcgi_param SCRIPT_FILENAME ${pkgs.writers.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};
'';
# Smart HTTP transport. Regex based on.
# https://github.com/git/git/blob/v2.27.0/http-backend.c#L708-L721
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 = ''
include ${pkgs.nginx}/conf/fastcgi_params;
fastcgi_param GIT_HTTP_EXPORT_ALL "";
fastcgi_param GIT_PROJECT_ROOT ${cfg.dataDir};
fastcgi_param HOME ${pkgs.write "git-http-backend.home" {
"/.gitconfig".text = /* ini */ ''
[safe]
directory = .
${concatMapStrings
(repo: "directory = ${cfg.dataDir}/${repo.name}\n")
(attrValues cfg.repos)
}
'';
}};
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;
'';
};
};
getName = x: x.name;
isPublicRepo = getAttr "public"; # TODO this is also in ./cgit.nix
makeAuthorizedKey = git-ssh-command: user@{ name, pubkey, ... }:
# 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
to-pattern = x: concatStringsSep "|" (toList x);
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
${concatStringsSep "\n" (map (go 1) patterns)}
exit -1
'';
reponames = rules: sort lessThan (unique (map (x: x.repo.name) rules));
# TODO use pkgs.write (from nix-writers)
scriptFarm =
farm-name: scripts:
let
makeScript = script-name: script-string: {
name = script-name;
path = pkgs.writeScript "${farm-name}_${script-name}" script-string;
};
in
pkgs.linkFarm farm-name (mapAttrsToList makeScript scripts);
git-ssh-command = pkgs.writeScript "git-ssh-command" ''
#! /bin/sh
set -euf
PATH=${makeBinPath (with pkgs; [
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" "$repodir"
'';
init-script = pkgs.writeScript "git-init" ''
#! /bin/sh
set -euf
PATH=${makeBinPath (with pkgs; [
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"
# TODO fix correctly with stringAfter
chown -R ${toString config.users.users.git.uid}:nogroup "$repodir"
fi
ln -Tfs ${hooks} "$repodir/hooks"
''
) (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 "$unknown_repos" | sed 's/^/ /')" \
>&2
fi
'';
makeHooks = repo: removeAttrs repo.hooks [ "pre-receive" ] // {
pre-receive = ''
#! /bin/sh
set -euf
PATH=${makeBinPath (with pkgs; [
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