diff options
Diffstat (limited to 'system/services/nix-sync/default.nix')
| -rw-r--r-- | system/services/nix-sync/default.nix | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/system/services/nix-sync/default.nix b/system/services/nix-sync/default.nix new file mode 100644 index 0000000..44348c0 --- /dev/null +++ b/system/services/nix-sync/default.nix @@ -0,0 +1,262 @@ +{ + config, + lib, + pkgs, + ... +}: let + cfg = config.services.nix-sync; + + mkTimer = name: repo: { + description = "Nix sync ${name} timer"; + wantedBy = ["timers.target"]; + timerConfig = { + OnActiveSec = repo.interval; + }; + after = ["network-online.target"]; + }; + + parents = path: let + split_path = builtins.split "/" path; + filename = builtins.elemAt split_path (builtins.length split_path - 1); + in + lib.strings.removeSuffix "/" (builtins.replaceStrings [filename] [""] path); + esa = lib.strings.escapeShellArg; + mkUnit = name: repo: let + optionalPathSeparator = + if lib.strings.hasPrefix "/" repo.path + then "" + else "/"; + repoCachePath = cfg.cachePath + optionalPathSeparator + repo.path; + execStartScript = pkgs.writeScript "nix-sync-exec" '' + #! /usr/bin/env dash + export XDG_CACHE_HOME="$CACHE_DIRECTORY"; + cd ${esa repoCachePath}; + + git fetch + origin="$(git rev-parse @{u})"; + branch="$(git rev-parse @)"; + + if ! [ "$origin" = "$branch" ]; then + git pull; + + out_paths=$(mktemp); + nix build . --print-out-paths --experimental-features 'nix-command flakes' > "$out_paths"; + [ "$(wc -l < "$out_paths")" -gt 1 ] && (echo "To many out-paths"; exit 1) + out_path="$(cat "$out_paths")"; + rm ${esa repo.path}; + ln -s "$out_path" ${esa repo.path}; + rm "$out_paths"; + fi + ''; + execStartPreScript = '' + export XDG_CACHE_HOME="$CACHE_DIRECTORY"; + + if ! [ -d ${esa repoCachePath}/.git ]; then + mkdir --parents ${esa repoCachePath}; + git clone ${esa repo.uri} ${esa repoCachePath}; + + out_paths=$(mktemp); + nix build ${esa repoCachePath} --print-out-paths --experimental-features 'nix-command flakes' > "$out_paths"; + [ "$(wc -l < "$out_paths")" -gt 1 ] && (echo "To many out-paths"; exit 1) + out_path="$(cat "$out_paths")"; + ln -s "$out_path" ${esa repo.path}; + rm "$out_paths"; + fi + + if ! [ -L ${esa repo.path} ]; then + cd ${esa repoCachePath}; + + git pull; + + out_paths=$(mktemp); + nix build . --print-out-paths --experimental-features 'nix-command flakes' > "$out_paths"; + [ "$(wc -l < "$out_paths")" -gt 1 ] && (echo "To many out-paths"; exit 1) + out_path="$(cat "$out_paths")"; + + [ -d ${esa repo.path} ] && rm -d ${esa repo.path}; + [ -e ${esa repo.path} ] && rm ${esa repo.path}; + + ln -s "$out_path" ${esa repo.path}; + rm "$out_paths"; + fi + ''; + in { + description = "Nix Sync ${name}"; + wantedBy = ["default.target"]; + after = ["network.target"]; + path = with pkgs; [openssh git nix mktemp coreutils dash]; + preStart = execStartPreScript; + + serviceConfig = { + ExecStart = execStartScript; + Restart = "on-abort"; + # User and group + User = cfg.user; + Group = cfg.group; + # Runtime directory and mode + RuntimeDirectory = "nix-sync"; + RuntimeDirectoryMode = "0750"; + # Cache directory and mode + CacheDirectory = "nix-sync"; + CacheDirectoryMode = "0750"; + # Logs directory and mode + LogsDirectory = "nix-sync"; + LogsDirectoryMode = "0750"; + # Proc filesystem + ProcSubset = "all"; + ProtectProc = "invisible"; + # New file permissions + UMask = "0027"; # 0640 / 0750 + # Capabilities + AmbientCapabilities = ["CAP_CHOWN"]; + CapabilityBoundingSet = ["CAP_CHOWN"]; + # Security + NoNewPrivileges = true; + # Sandboxing (sorted by occurrence in https://www.freedesktop.org/software/systemd/man/systemd.exec.html) + ReadWritePaths = ["${esa (parents repo.path)}" "-${esa repoCachePath}" "-${esa cfg.cachePath}"]; + ReadOnlyPaths = ["/nix"]; + ProtectSystem = "strict"; + ProtectHome = true; + PrivateTmp = true; + PrivateDevices = true; + ProtectHostname = true; + ProtectClock = true; + ProtectKernelTunables = true; + ProtectKernelModules = true; + ProtectKernelLogs = true; + ProtectControlGroups = true; + RestrictAddressFamilies = ["AF_UNIX" "AF_INET" "AF_INET6"]; + RestrictNamespaces = true; + LockPersonality = true; + MemoryDenyWriteExecute = true; + RestrictRealtime = true; + RestrictSUIDSGID = true; + RemoveIPC = true; + PrivateMounts = true; + # System Call Filtering + SystemCallArchitectures = "native"; + SystemCallFilter = ["~@cpu-emulation @debug @keyring @mount @obsolete @privileged @setuid"]; + }; + }; + + services = + lib.mapAttrs' (name: repo: { + name = "nix-sync-${name}"; + value = mkUnit name repo; + }) + cfg.repositories; + timers = + lib.mapAttrs' (name: repo: { + name = "nix-sync-${name}"; + value = mkTimer name repo; + }) + cfg.repositories; + + # generate the websites directory, so systemd can mount it read write + generatedDirectories = + lib.mapAttrsToList ( + _: repo: "d ${esa (parents repo.path)} 0755 ${cfg.user} ${cfg.group}" + ) + cfg.repositories; + + repositoryType = lib.types.submodule ({name, ...}: { + options = { + name = lib.mkOption { + internal = true; + default = name; + type = lib.types.str; + description = "The name that should be given to this unit."; + }; + + path = lib.mkOption { + type = lib.types.str; + description = "The path at which to sync the repository"; + }; + + uri = lib.mkOption { + type = lib.types.str; + example = "ssh://user@example.com:/~[user]/path/to/repo.git"; + description = '' + The URI of the remote to be synchronized. This is only used in the + event that the directory does not already exist. See + <link xlink:href="https://git-scm.com/docs/git-clone#_git_urls"/> + for the supported URIs. + ''; + }; + + interval = lib.mkOption { + type = lib.types.int; + default = 500; + description = '' + The interval, specified in seconds, at which the synchronization will + be triggered. + ''; + }; + }; + }); +in { + options = { + services.nix-sync = { + enable = lib.mkEnableOption "nix-sync services"; + + user = lib.mkOption { + type = lib.types.str; + default = "nix-sync"; + description = lib.mdDoc "User account under which nix-sync units runs."; + }; + + group = lib.mkOption { + type = lib.types.str; + default = "nix-sync"; + description = lib.mdDoc "Group account under which nix-sync units runs."; + }; + + cachePath = lib.mkOption { + type = lib.types.str; + default = "/var/lib/nix-sync"; + description = lib.mdDoc '' + Where to cache git directories. Should not end with a slash ("/") + ''; + }; + + repositories = lib.mkOption { + type = with lib.types; attrsOf repositoryType; + description = '' + The repositories that should be synchronized. + ''; + }; + }; + }; + + config = lib.mkIf cfg.enable { + assertions = [ + { + assertion = !lib.strings.hasSuffix "/" cfg.cachePath; + message = "Your cachePath ('${cfg.cachePath}') ends with a slash ('/'), please use: '${lib.strings.removeSuffix "/" cfg.cachePath}'."; + } + ]; + + systemd.tmpfiles.rules = + generatedDirectories; + + systemd.services = services; + systemd.timers = timers; + users.users = + if cfg.user == "nix-sync" + then { + nix-sync = { + group = "${cfg.group}"; + isSystemUser = true; + }; + } + else lib.warnIf (cfg.user != "nix-sync") "The user (${cfg.user}) is not \"nix-sync\", thus you are responible for generating it."; + users.groups = + if cfg.group == "nix-sync" + then { + nix-sync = { + members = ["${cfg.user}"]; + }; + } + else lib.warnIf (cfg.group != "nix-sync") "The group (${cfg.group}) is not \"nix-sync\", thus you are responible for generating it."; + }; +} |