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 config.krebs.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 [
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(mkIf cfg.cgit cgit-imp)
git-imp
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]);
};
api = {
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enable = mkEnableOption "krebs.git";
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cgit = mkOption {
type = types.bool;
default = true;
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description = ''
Enable cgit.
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
deploys a http://cgit.<hostname> nginx configuration and enables nginx
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 = types.str;
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.
'';
};
root-desc = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
Text printed below the heading on the repository index page.
Default value: "a fast webinterface for the git dscm".
'';
};
root-title = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
Text printed as heading on the repository index page.
Default value: "Git Repository Browser".
'';
};
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 config.krebs.lib.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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};
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# TODO put into krebs/4lib/types.nix?
subtypes = {
repo = types.submodule ({
options = {
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.
'';
};
desc = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
Repository description.
'';
};
section = mkOption {
type = types.nullOr types.str;
default = null;
description = ''
Repository section.
'';
};
name = mkOption {
type = types.str;
description = ''
Repository name.
'';
};
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."${etc-base}".source =
scriptFarm "git-ssh-authorizers" {
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authorize-command = makeAuthorizeScript (map (rule: [
(map getName (ensureList rule.user))
(map getName (ensureList rule.repo))
(map getName rule.perm.allow-commands)
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]) cfg.rules);
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authorize-push = makeAuthorizeScript (map (rule: [
(map getName (ensureList rule.user))
(map getName (ensureList rule.repo))
(ensureList rule.perm.allow-receive-ref)
(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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# TODO cfg.user
users.users.git = rec {
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description = "Git repository hosting user";
name = "git";
shell = "/bin/sh";
openssh.authorizedKeys.keys =
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mapAttrsToList (_: makeAuthorizedKey git-ssh-command)
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(filterAttrs (_: user: isString user.pubkey)
config.krebs.users);
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uid = genid name;
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};
};
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cgit-imp = {
users.extraUsers = lib.singleton {
inherit (fcgitwrap-user) group name uid;
home = toString (pkgs.runCommand "empty" {} "mkdir -p $out");
};
users.extraGroups = lib.singleton {
inherit (fcgitwrap-group) gid name;
};
services.fcgiwrap = {
enable = true;
user = fcgitwrap-user.name;
group = fcgitwrap-user.group;
# socketAddress = "/run/fcgiwrap.sock" (default)
# socketType = "unix" (default)
};
environment.etc."cgitrc".text = ''
css=/static/cgit.css
logo=/static/cgit.png
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# if you do not want that webcrawler (like google) index your site
robots=noindex, nofollow
virtual-root=/
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# TODO make this nicer (and/or somewhere else)
cache-root=/tmp/cgit
cache-size=1000
enable-commit-graph=1
enable-index-links=1
enable-index-owner=0
enable-log-filecount=1
enable-log-linecount=1
enable-remote-branches=1
${optionalString (cfg.root-title != null) "root-title=${cfg.root-title}"}
${optionalString (cfg.root-desc != null) "root-desc=${cfg.root-desc}"}
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snapshots=0
max-stats=year
${concatMapStringsSep "\n" (repo: ''
repo.url=${repo.name}
repo.path=${cfg.dataDir}/${repo.name}
${optionalString (repo.section != null) "repo.section=${repo.section}"}
${optionalString (repo.desc != null) "repo.desc=${repo.desc}"}
'') (filter isPublicRepo (attrValues cfg.repos))}
'';
system.activationScripts.cgit = ''
mkdir -m 0700 -p /tmp/cgit
chown ${toString fcgitwrap-user.uid}:${toString fcgitwrap-group.gid} /tmp/cgit
'';
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krebs.nginx = {
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enable = true;
servers.cgit = {
server-names = [
"cgit.${config.networking.hostName}"
"cgit.${config.networking.hostName}.retiolum"
];
locations = [
(nameValuePair "/" ''
include ${pkgs.nginx}/conf/fastcgi_params;
fastcgi_param SCRIPT_FILENAME ${pkgs.cgit}/cgit/cgit.cgi;
fastcgi_param PATH_INFO $uri;
fastcgi_param QUERY_STRING $args;
fastcgi_param HTTP_HOST $server_name;
fastcgi_pass unix:${config.services.fcgiwrap.socketAddress};
'')
(nameValuePair "/static/" ''
root ${pkgs.cgit}/cgit;
rewrite ^/static(/.*)$ $1 break;
'')
];
};
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};
};
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fcgitwrap-user = rec {
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name = "fcgiwrap";
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uid = genid name;
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group = "fcgiwrap";
};
fcgitwrap-group = {
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name = fcgitwrap-user.name;
gid = fcgitwrap-user.uid;
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};
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ensureList = x:
if typeOf x == "list" then x else [x];
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
to-pattern = x: concatStringsSep "|" (ensureList 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
${concatStringsSep "\n" (map (go 1) patterns)}
exit -1
'';
reponames = rules: sort lessThan (unique (map (x: x.repo.name) rules));
# TODO makeGitHooks that uses runCommand instead of scriptFarm?
scriptFarm =
farm-name: scripts:
let
makeScript = script-name: script-string: {
name = script-name;
path = pkgs.writeScript "${farm-name}_${script-name}" script-string;
};
in
pkgs.linkFarm farm-name (mapAttrsToList makeScript scripts);
git-ssh-command = pkgs.writeScript "git-ssh-command" ''
#! /bin/sh
set -euf
PATH=${makeSearchPath "bin" (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" "$repodir"
'';
init-script = pkgs.writeScript "git-init" ''
#! /bin/sh
set -euf
PATH=${makeSearchPath "bin" (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 "$repodir"
chown -R git:nogroup "$repodir"
fi
ln -s ${hooks} "$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 "$unknown_repos" | sed 's/^/ /')" \
>&2
fi
'';
makeHooks = repo: removeAttrs repo.hooks [ "pre-receive" ] // {
pre-receive = ''
#! /bin/sh
set -euf
PATH=${makeSearchPath "bin" (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}''}
'';
};
etc-base =
assert (hasPrefix "/etc/" cfg.etcDir);
removePrefix "/etc/" cfg.etcDir;
in
out