diff options
Diffstat (limited to 'nixos/modules/services/logging/journalwatch.nix')
| -rw-r--r-- | nixos/modules/services/logging/journalwatch.nix | 265 |
1 files changed, 265 insertions, 0 deletions
diff --git a/nixos/modules/services/logging/journalwatch.nix b/nixos/modules/services/logging/journalwatch.nix new file mode 100644 index 00000000000..fb86904d1ea --- /dev/null +++ b/nixos/modules/services/logging/journalwatch.nix @@ -0,0 +1,265 @@ +{ config, lib, pkgs, ... }: +with lib; + +let + cfg = config.services.journalwatch; + user = "journalwatch"; + # for journal access + group = "systemd-journal"; + dataDir = "/var/lib/${user}"; + + journalwatchConfig = pkgs.writeText "config" ('' + # (File Generated by NixOS journalwatch module.) + [DEFAULT] + mail_binary = ${cfg.mailBinary} + priority = ${toString cfg.priority} + mail_from = ${cfg.mailFrom} + '' + + optionalString (cfg.mailTo != null) '' + mail_to = ${cfg.mailTo} + '' + + cfg.extraConfig); + + journalwatchPatterns = pkgs.writeText "patterns" '' + # (File Generated by NixOS journalwatch module.) + + ${mkPatterns cfg.filterBlocks} + ''; + + # empty line at the end needed to to separate the blocks + mkPatterns = filterBlocks: concatStringsSep "\n" (map (block: '' + ${block.match} + ${block.filters} + + '') filterBlocks); + + # can't use joinSymlinks directly, because when we point $XDG_CONFIG_HOME + # to the /nix/store path, we still need the subdirectory "journalwatch" inside that + # to match journalwatch's expectations + journalwatchConfigDir = pkgs.runCommand "journalwatch-config" + { preferLocalBuild = true; allowSubstitutes = false; } + '' + mkdir -p $out/journalwatch + ln -sf ${journalwatchConfig} $out/journalwatch/config + ln -sf ${journalwatchPatterns} $out/journalwatch/patterns + ''; + + +in { + options = { + services.journalwatch = { + enable = mkOption { + type = types.bool; + default = false; + description = '' + If enabled, periodically check the journal with journalwatch and report the results by mail. + ''; + }; + + priority = mkOption { + type = types.int; + default = 6; + description = '' + Lowest priority of message to be considered. + A value between 7 ("debug"), and 0 ("emerg"). Defaults to 6 ("info"). + If you don't care about anything with "info" priority, you can reduce + this to e.g. 5 ("notice") to considerably reduce the amount of + messages without needing many <option>filterBlocks</option>. + ''; + }; + + # HACK: this is a workaround for journalwatch's usage of socket.getfqdn() which always returns localhost if + # there's an alias for the localhost on a separate line in /etc/hosts, or take for ages if it's not present and + # then return something right-ish in the direction of /etc/hostname. Just bypass it completely. + mailFrom = mkOption { + type = types.str; + default = "journalwatch@${config.networking.hostName}"; + defaultText = literalExpression ''"journalwatch@''${config.networking.hostName}"''; + description = '' + Mail address to send journalwatch reports from. + ''; + }; + + mailTo = mkOption { + type = types.nullOr types.str; + default = null; + description = '' + Mail address to send journalwatch reports to. + ''; + }; + + mailBinary = mkOption { + type = types.path; + default = "/run/wrappers/bin/sendmail"; + description = '' + Sendmail-compatible binary to be used to send the messages. + ''; + }; + + extraConfig = mkOption { + type = types.str; + default = ""; + description = '' + Extra lines to be added verbatim to the journalwatch/config configuration file. + You can add any commandline argument to the config, without the '--'. + See <literal>journalwatch --help</literal> for all arguments and their description. + ''; + }; + + filterBlocks = mkOption { + type = types.listOf (types.submodule { + options = { + match = mkOption { + type = types.str; + example = "SYSLOG_IDENTIFIER = systemd"; + description = '' + Syntax: <literal>field = value</literal> + Specifies the log entry <literal>field</literal> this block should apply to. + If the <literal>field</literal> of a message matches this <literal>value</literal>, + this patternBlock's <option>filters</option> are applied. + If <literal>value</literal> starts and ends with a slash, it is interpreted as + an extended python regular expression, if not, it's an exact match. + The journal fields are explained in systemd.journal-fields(7). + ''; + }; + + filters = mkOption { + type = types.str; + example = '' + (Stopped|Stopping|Starting|Started) .* + (Reached target|Stopped target) .* + ''; + description = '' + The filters to apply on all messages which satisfy <option>match</option>. + Any of those messages that match any specified filter will be removed from journalwatch's output. + Each filter is an extended Python regular expression. + You can specify multiple filters and separate them by newlines. + Lines starting with '#' are comments. Inline-comments are not permitted. + ''; + }; + }; + }); + + example = [ + # examples taken from upstream + { + match = "_SYSTEMD_UNIT = systemd-logind.service"; + filters = '' + New session [a-z]?\d+ of user \w+\. + Removed session [a-z]?\d+\. + ''; + } + + { + match = "SYSLOG_IDENTIFIER = /(CROND|crond)/"; + filters = '' + pam_unix\(crond:session\): session (opened|closed) for user \w+ + \(\w+\) CMD .* + ''; + } + ]; + + # another example from upstream. + # very useful on priority = 6, and required as journalwatch throws an error when no pattern is defined at all. + default = [ + { + match = "SYSLOG_IDENTIFIER = systemd"; + filters = '' + (Stopped|Stopping|Starting|Started) .* + (Created slice|Removed slice) user-\d*\.slice\. + Received SIGRTMIN\+24 from PID .* + (Reached target|Stopped target) .* + Startup finished in \d*ms\. + ''; + } + ]; + + + description = '' + filterBlocks can be defined to blacklist journal messages which are not errors. + Each block matches on a log entry field, and the filters in that block then are matched + against all messages with a matching log entry field. + + All messages whose PRIORITY is at least 6 (INFO) are processed by journalwatch. + If you don't specify any filterBlocks, PRIORITY is reduced to 5 (NOTICE) by default. + + All regular expressions are extended Python regular expressions, for details + see: http://doc.pyschools.com/html/regex.html + ''; + }; + + interval = mkOption { + type = types.str; + default = "hourly"; + description = '' + How often to run journalwatch. + + The format is described in systemd.time(7). + ''; + }; + accuracy = mkOption { + type = types.str; + default = "10min"; + description = '' + The time window around the interval in which the journalwatch run will be scheduled. + + The format is described in systemd.time(7). + ''; + }; + }; + }; + + config = mkIf cfg.enable { + + users.users.${user} = { + isSystemUser = true; + home = dataDir; + group = group; + }; + + systemd.tmpfiles.rules = [ + # present since NixOS 19.09: remove old stateful symlink join directory, + # which has been replaced with the journalwatchConfigDir store path + "R ${dataDir}/config" + ]; + + systemd.services.journalwatch = { + + environment = { + # journalwatch stores the last processed timpestamp here + # the share subdirectory is historic now that config home lives in /nix/store, + # but moving this in a backwards-compatible way is much more work than what's justified + # for cleaning that up. + XDG_DATA_HOME = "${dataDir}/share"; + XDG_CONFIG_HOME = journalwatchConfigDir; + }; + serviceConfig = { + User = user; + Group = group; + Type = "oneshot"; + # requires a relative directory name to create beneath /var/lib + StateDirectory = user; + StateDirectoryMode = 0750; + ExecStart = "${pkgs.python3Packages.journalwatch}/bin/journalwatch mail"; + # lowest CPU and IO priority, but both still in best-effort class to prevent starvation + Nice=19; + IOSchedulingPriority=7; + }; + }; + + systemd.timers.journalwatch = { + description = "Periodic journalwatch run"; + wantedBy = [ "timers.target" ]; + timerConfig = { + OnCalendar = cfg.interval; + AccuracySec = cfg.accuracy; + Persistent = true; + }; + }; + + }; + + meta = { + maintainers = with lib.maintainers; [ florianjacob ]; + }; +} |