From 734ec4ae00c93d48297b7c3ee226ef890187bfa3 Mon Sep 17 00:00:00 2001
From: tv <tv@shackspace.de>
Date: Fri, 24 Jul 2015 11:50:23 +0200
Subject: 3 {tv -> krebs}.nginx

---
 3modules/krebs/nginx.nix | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 3modules/krebs/nginx.nix

(limited to '3modules/krebs')

diff --git a/3modules/krebs/nginx.nix b/3modules/krebs/nginx.nix
new file mode 100644
index 000000000..702e8a7f6
--- /dev/null
+++ b/3modules/krebs/nginx.nix
@@ -0,0 +1,72 @@
+{ config, pkgs, lib, ... }:
+
+with builtins;
+with lib;
+let
+  cfg = config.krebs.nginx;
+
+  out = {
+    options.krebs.nginx = api;
+    config = mkIf cfg.enable imp;
+  };
+
+  api = {
+    enable = mkEnableOption "krebs.nginx";
+
+    servers = mkOption {
+      type = with types; attrsOf optionSet;
+      options = singleton {
+        server-names = mkOption {
+          type = with types; listOf str;
+          # TODO use identity
+          default = [
+            "${config.networking.hostName}"
+            "${config.networking.hostName}.retiolum"
+          ];
+        };
+        locations = mkOption {
+          type = with types; listOf (attrsOf str);
+        };
+      };
+      default = {};
+    };
+  };
+
+  imp = {
+    services.nginx = {
+      enable = true;
+      httpConfig = ''
+        include           ${pkgs.nginx}/conf/mime.types;
+        default_type      application/octet-stream;
+        sendfile          on;
+        keepalive_timeout 65;
+        gzip              on;
+        server {
+          listen 80 default_server;
+          server_name _;
+          return 404;
+        }
+        ${concatStrings (mapAttrsToList (_: to-server) cfg.servers)}
+      '';
+    };
+  };
+
+  
+  indent = replaceChars ["\n"] ["\n  "];
+
+  to-location = { name, value }: ''
+    location ${name} {
+      ${indent value}
+    }
+  '';
+
+  to-server = { server-names, locations, ... }: ''
+    server {
+      listen 80;
+      server_name ${toString server-names};
+      ${indent (concatStrings (map to-location locations))}
+    }
+  '';
+
+in
+out
-- 
cgit v1.2.3


From 5f63c4071c7b1680e75671c0acede8a9bce4b14c Mon Sep 17 00:00:00 2001
From: tv <tv@shackspace.de>
Date: Fri, 24 Jul 2015 11:44:49 +0200
Subject: 3: {tv -> krebs}.git

---
 3modules/krebs/git.nix | 484 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 484 insertions(+)
 create mode 100644 3modules/krebs/git.nix

(limited to '3modules/krebs')

diff --git a/3modules/krebs/git.nix b/3modules/krebs/git.nix
new file mode 100644
index 000000000..3c3e93426
--- /dev/null
+++ b/3modules/krebs/git.nix
@@ -0,0 +1,484 @@
+{ config, pkgs, lib, ... }:
+
+# 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 builtins;
+with lib;
+let
+  cfg = config.krebs.git;
+
+  out = {
+    # TODO don't import krebs.nginx here
+    imports = [
+      ../../3modules/krebs/nginx.nix
+    ];
+    options.krebs.git = api;
+    config = mkIf cfg.enable (mkMerge [
+      (mkIf cfg.cgit cgit-imp)
+      git-imp
+    ]);
+  };
+
+  api = {
+    enable = mkEnableOption "krebs.git";
+
+    cgit = mkOption {
+      type = types.bool;
+      default = true;
+      description = "Enable cgit."; # TODO better desc; talk about nginx
+    };
+    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 {
+      type = types.attrsOf (types.submodule ({
+        options = {
+          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;
+            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.
+          };
+        };
+      }));
+
+      default = {};
+
+      example = literalExample ''
+        {
+          testing = {
+            name = "testing";
+            hooks.post-update = '''
+              #! /bin/sh
+              set -euf
+              echo post-update hook: $* >&2
+            ''';
+          };
+          testing2 = { name = "testing2"; };
+        }
+      '';
+
+      description = ''
+        Repositories.
+      '';
+    };
+    root-desc = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = ''
+        Text printed below the heading on the repository index page.
+        Default value: "a fast webinterface for the git dscm".
+      '';
+    };
+    root-title = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = ''
+        Text printed as heading on the repository index page.
+        Default value: "Git Repository Browser".
+      '';
+    };
+    rules = mkOption {
+      type = types.unspecified;
+    };
+    users = mkOption {
+      type = types.unspecified;
+    };
+  };
+
+  git-imp = {
+    system.activationScripts.git-init = "${init-script}";
+    
+    # TODO maybe put all scripts here and then use PATH?
+    environment.etc."${etc-base}".source =
+      scriptFarm "git-ssh-authorizers" {
+        authorize-command = makeAuthorizeScript (map ({ repo, user, perm }: [
+          (map getName (ensureList user))
+          (map getName (ensureList repo))
+          (map getName perm.allow-commands)
+        ]) cfg.rules);
+    
+        authorize-push = makeAuthorizeScript (map ({ repo, user, perm }: [
+          (map getName (ensureList user))
+          (map getName (ensureList repo))
+          (ensureList perm.allow-receive-ref)
+          (map getName perm.allow-receive-modes)
+        ]) (filter (x: hasAttr "allow-receive-ref" x.perm) cfg.rules));
+      };
+    
+    users.extraUsers = singleton {
+      description = "Git repository hosting user";
+      name = "git";
+      shell = "/bin/sh";
+      openssh.authorizedKeys.keys =
+        mapAttrsToList (_: makeAuthorizedKey git-ssh-command) cfg.users;
+      uid = 129318403; # genid git
+    };
+  };
+
+  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
+
+      # if you do not want that webcrawler (like google) index your site
+      robots=noindex, nofollow
+
+      virtual-root=/
+
+      # 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}"}
+
+      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
+    '';
+
+    krebs.nginx = {
+      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;
+          '')
+        ];
+      };
+    };
+  };
+
+  fcgitwrap-user = {
+    name = "fcgiwrap";
+    uid = 2867890860; # genid fcgiwrap
+    group = "fcgiwrap";
+  };
+
+  fcgitwrap-group = {
+    name = fcgitwrap-user.name;
+    gid = fcgitwrap-user.uid;
+  };
+
+
+  ensureList = x:
+    if typeOf x == "list" then x else [x];
+
+  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 "|" (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 $SSH_ORIGINAL_COMMAND"
+
+    # References: The Base Definitions volume of
+    # POSIX.1‐2013, Section 3.278, Portable Filename Character Set
+    portable_filename_bre="^[A-Za-z0-9._-]\\+$"
+
+    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
-- 
cgit v1.2.3


From b6987329fe6dca5aca96fc651f06867c26dbf236 Mon Sep 17 00:00:00 2001
From: tv <tv@shackspace.de>
Date: Fri, 24 Jul 2015 11:55:16 +0200
Subject: 3: {tv -> krebs}.urlwatch

---
 3modules/krebs/urlwatch.nix | 136 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100644 3modules/krebs/urlwatch.nix

(limited to '3modules/krebs')

diff --git a/3modules/krebs/urlwatch.nix b/3modules/krebs/urlwatch.nix
new file mode 100644
index 000000000..58de72fc6
--- /dev/null
+++ b/3modules/krebs/urlwatch.nix
@@ -0,0 +1,136 @@
+{ config, lib, pkgs, ... }:
+
+# TODO multiple users
+# TODO inform about unused caches
+# cache = url: "${cfg.dataDir}/.urlwatch/cache/${hashString "sha1" url}"
+# TODO hooks.py
+
+with builtins;
+with lib;
+let
+  cfg = config.krebs.urlwatch;
+
+  # TODO assert sendmail's existence
+  out = {
+    options.krebs.urlwatch = api;
+    config = mkIf cfg.enable imp;
+  };
+
+  api = {
+    enable = mkEnableOption "krebs.urlwatch";
+
+    dataDir = mkOption {
+      type = types.str;
+      default = "/var/lib/urlwatch";
+      description = ''
+        Directory where the urlwatch service should store its state.
+      '';
+    };
+    from = mkOption {
+      type = types.str;
+      default = "${user.name}@${config.networking.hostName}.retiolum";
+      description = ''
+        Content of the From: header of the generated mails.
+      '';
+    };
+    mailto = mkOption {
+      type = types.str;
+      description = ''
+        Content of the To: header of the generated mails. [AKA recipient :)]
+      '';
+    };
+    onCalendar = mkOption {
+      type = types.str;
+      description = ''
+        Run urlwatch at this interval.
+        The format is described in systemd.time(7), CALENDAR EVENTS.
+      '';
+      example = "04:23";
+    };
+    urls = mkOption {
+      type = with types; listOf str;
+      description = "URL to watch.";
+      example = [
+        https://nixos.org/channels/nixos-unstable/git-revision
+      ];
+    };
+  };
+
+  urlsFile = toFile "urls" (concatStringsSep "\n" cfg.urls);
+
+  imp = {
+    systemd.timers.urlwatch = {
+      wantedBy = [ "timers.target" ];
+      timerConfig = {
+        OnCalendar = cfg.onCalendar;
+        Persistent = "true";
+      };
+    };
+    systemd.services.urlwatch = {
+      path = with pkgs; [
+        coreutils
+        gnused
+        urlwatch
+      ];
+      environment = {
+        HOME = cfg.dataDir;
+        LC_ALL = "en_US.UTF-8";
+        LOCALE_ARCHIVE = "${pkgs.glibcLocales}/lib/locale/locale-archive";
+        SSL_CERT_FILE = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
+      };
+      serviceConfig = {
+        User = user.name;
+        PermissionsStartOnly = "true";
+        PrivateTmp = "true";
+        Type = "oneshot";
+        ExecStartPre =
+          pkgs.writeScript "urlwatch-prestart" ''
+            #! /bin/sh
+            set -euf
+
+            dataDir=$HOME
+
+            if ! test -e "$dataDir"; then
+              mkdir -m 0700 -p "$dataDir"
+              chown ${user.name}: "$dataDir"
+            fi
+          '';
+        ExecStart = pkgs.writeScript "urlwatch" ''
+          #! /bin/sh
+          set -euf
+
+          from=${escapeShellArg cfg.from}
+          mailto=${escapeShellArg cfg.mailto}
+          urlsFile=${escapeShellArg urlsFile}
+
+          cd /tmp
+
+          urlwatch -e --urls="$urlsFile" > changes 2>&1 || :
+
+          if test -s changes; then
+            date=$(date -R)
+            subject=$(sed -n 's/^\(CHANGED\|ERROR\|NEW\): //p' changes \
+              | tr \\n \ )
+            {
+              echo "Date: $date"
+              echo "From: $from"
+              echo "Subject: $subject"
+              echo "To: $mailto"
+              echo
+              cat changes
+            } | /var/setuid-wrappers/sendmail -t
+          fi
+        '';
+      };
+    };
+    users.extraUsers = singleton {
+      inherit (user) name uid;
+    };
+  };
+
+  user = {
+    name = "urlwatch";
+    uid = 3467631196; # genid urlwatch
+  };
+in
+out
-- 
cgit v1.2.3


From e3b72bb66e7c6bf410c8db81ff04e355a7b22116 Mon Sep 17 00:00:00 2001
From: tv <tv@shackspace.de>
Date: Fri, 24 Jul 2015 12:03:51 +0200
Subject: 3: {tv -> krebs}.github-hosts-sync

---
 3modules/krebs/github-hosts-sync.nix | 83 ++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 3modules/krebs/github-hosts-sync.nix

(limited to '3modules/krebs')

diff --git a/3modules/krebs/github-hosts-sync.nix b/3modules/krebs/github-hosts-sync.nix
new file mode 100644
index 000000000..c3b56ef94
--- /dev/null
+++ b/3modules/krebs/github-hosts-sync.nix
@@ -0,0 +1,83 @@
+{ config, lib, pkgs, ... }:
+
+with builtins;
+with lib;
+let
+  cfg = config.krebs.github-hosts-sync;
+
+  out = {
+    options.krebs.github-hosts-sync = api;
+    config = mkIf cfg.enable imp;
+  };
+
+  api = {
+    enable = mkEnableOption "krebs.github-hosts-sync";
+    port = mkOption {
+      type = types.int; # TODO port type
+      default = 1028;
+    };
+    dataDir = mkOption {
+      type = types.str; # TODO path (but not just into store)
+      default = "/var/lib/github-hosts-sync";
+    };
+    ssh-identity-file = mkOption {
+      type = types.str; # TODO must be named *.ssh.{id_rsa,id_ed25519}
+      default = "/root/src/secrets/github-hosts-sync.ssh.id_rsa";
+    };
+  };
+
+  imp = {
+    systemd.services.github-hosts-sync = {
+      after = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+      environment = {
+        port = toString cfg.port;
+      };
+      serviceConfig = {
+        PermissionsStartOnly = "true";
+        SyslogIdentifier = "github-hosts-sync";
+        User = user.name;
+        Restart = "always";
+        ExecStartPre = pkgs.writeScript "github-hosts-sync-init" ''
+          #! /bin/sh
+          set -euf
+
+          ssh_identity_file_target=$(
+            case ${cfg.ssh-identity-file} in
+              *.ssh.id_rsa|*.ssh.id_ed25519) echo ${cfg.dataDir}/.ssh/id_rsa;;
+              *.ssh.id_ed25519) echo ${cfg.dataDir}/.ssh/id_ed25519;;
+              *)
+                echo "bad identity file name: ${cfg.ssh-identity-file}" >&2
+                exit 1
+            esac
+          )
+
+          mkdir -p ${cfg.dataDir}
+          chown ${user.name}: ${cfg.dataDir}
+
+          install \
+            -o ${user.name} \
+            -m 0400 \
+            ${cfg.ssh-identity-file} \
+            "$ssh_identity_file_target"
+
+          ln -snf ${Zpkgs.github-known_hosts} ${cfg.dataDir}/.ssh/known_hosts
+        '';
+        ExecStart = "${Zpkgs.github-hosts-sync}/bin/github-hosts-sync";
+      };
+    };
+
+    users.extraUsers = singleton {
+      inherit (user) name uid;
+      home = cfg.dataDir;
+    };
+  };
+
+  user = {
+    name = "github-hosts-sync";
+    uid = 3220554646; # genid github-hosts-sync
+  };
+
+  Zpkgs = import ../../Zpkgs/krebs { inherit pkgs; };
+in
+out
-- 
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