{ config, pkgs, ... }: with pkgs.lib; let cfg = config.services.logstash; listToConfig = list: "[ " + (concatStringsSep ", " (map exprToConfig list)) + " ]"; hashToConfig = attrs: let attrNameToConfigList = name: [ (exprToConfig name) (exprToConfig (getAttr name attrs)) ]; in "[ " + (concatStringsSep ", " (map attrNameToConfigList (attrNames attrs))) + " ]"; valueToConfig = nvpair: let name = nvpair.name; value = nvpair.value; in if (isAttrs value) && ((!(value ? __type)) || value.__type == "repeated") then '' ${name} { ${exprToConfig value} } '' else "${name} => ${exprToConfig value}"; repeatedAttrsToConfig = values: concatStringsSep "\n" (map valueToConfig values); attrsToConfig = attrs: let attrToConfig = name: valueToConfig { inherit name; value = (getAttr name attrs); }; in concatStringsSep "\n" (map attrToConfig (attrNames attrs)); exprToConfig = expr: let isCustomType = expr: (isAttrs expr) && (expr ? __type); isFloat = expr: (isCustomType expr) && (expr.__type == "float"); isHash = expr: (isCustomType expr) && (expr.__type == "hash"); isRepeatedAttrs = expr: (isCustomType expr) && (expr.__type == "repeated"); in if builtins.isBool expr then (if expr then "true" else "false") else if builtins.isString expr then ''"${expr}"'' else if builtins.isInt expr then toString expr else if isFloat expr then expr.value else if isList expr then listToConfig expr else if isHash expr then hashToConfig expr.value else if isRepeatedAttrs expr then repeatedAttrsToConfig expr.values else attrsToConfig expr; mergeConfigs = configs: let op = attrs: newAttrs: let isRepeated = newAttrs ? __type && newAttrs.__type == "repeated"; in { values = attrs.values ++ (if isRepeated then newAttrs.values else map (name: { inherit name; value = getAttr name newAttrs; }) (attrNames newAttrs)); }; in (foldl op { values = []; } configs) // { __type = "repeated"; }; in { ###### interface options = { services.logstash = { enable = mkOption { default = false; description = '' Enable logstash. ''; }; inputConfig = mkOption { default = {}; description = '' An attribute set (or an expression generated by mkNameValuePairs) representing a logstash configuration's input section. Logstash configs are name-value pairs, where values can be bools, strings, numbers, arrays, hashes, or other name-value pairs, and names are strings that can be repeated. Name-value pairs with no repeats are represented by attr sets. Bools, strings, ints, and arrays are mapped directly. Name-value pairs with repeats can be generated by the config.lib.logstash.mkNameValuePairs function, which takes a list of attrsets and combines them while preserving attribute name duplicates if they occur. Similarly, there are the mkFloat and mkHash functions, which take a string representation of a float and an attrset, respectively. ''; apply = mergeConfigs; }; filterConfig = mkOption { default = {}; description = '' An attribute set (or an expression generated by mkNameValuePairs) representing a logstash configuration's filter section. See inputConfig description for details. ''; apply = mergeConfigs; }; outputConfig = mkOption { default = {}; description = '' An attribute set (or an expression generated by mkNameValuePairs) representing a logstash configuration's output section. See inputConfig description for details. ''; apply = mergeConfigs; }; }; }; ###### implementation config = mkMerge [ { lib.logstash = { mkFloat = stringRep: { __type = "float"; value = stringRep; }; mkHash = attrs: { __type = "hash"; value = attrs; }; mkNameValuePairs = mergeConfigs; }; } ( mkIf cfg.enable { systemd.services.logstash = with pkgs; { description = "Logstash daemon"; wantedBy = [ "multi-user.target" ]; path = [ jre ]; script = "cd /tmp && exec java -jar ${logstash} agent -f ${writeText "logstash.conf" '' input { ${exprToConfig cfg.inputConfig} } filter { ${exprToConfig cfg.filterConfig} } output { ${exprToConfig cfg.outputConfig} } ''} &> /var/log/logstash.log"; }; })]; }