config(modules/nethermind): Add argsFromFile option

Author: MartinNikov

modules/nethermind/default.nix

@@ -4,31 +4,20 @@
   pkgs,
   ...
 }: let
-  inherit
-    (builtins)
-    isBool
-    isList
-    toString
-    ;
-  inherit
-    (lib)
-    boolToString
-    concatStringsSep
-    filterAttrs
-    findFirst
-    flatten
-    hasPrefix
-    mapAttrs'
-    mapAttrsToList
-    mkIf
-    mkMerge
-    nameValuePair
-    optionals
-    zipAttrsWith
-    ;
+  serviceArgs =
+    lib.mapAttrs (
+      nethermindName: let
+        serviceName = "nethermind-${nethermindName}";
+      in
+        cfg: ((import ./service-args.nix {inherit lib pkgs;}).argsCreate serviceName cfg)
+    )
+    eachNethermind;
+
+  inherit (builtins) toString;
+  inherit (lib) filterAttrs flatten mapAttrs' mapAttrsToList mkIf mkMerge nameValuePair optionals zipAttrsWith;
 
   modulesLib = import ../lib.nix lib;
-  inherit (modulesLib) mkArgs baseServiceConfig;
+  inherit (modulesLib) baseServiceConfig;
 
   # capture config for all configured netherminds
   eachNethermind = config.services.ethereum.nethermind;
@@ -58,67 +47,29 @@ in {
     in
       zipAttrsWith (_name: flatten) perService;
 
+    environment = lib.mapAttrs' (nethermindName: cfg:
+      lib.nameValuePair "etc" {
+        "ethereum/nethermind-${nethermindName}-args" = let
+          argsFromFile = cfg.argsFromFile;
+        in
+          lib.mkIf argsFromFile.enable {
+            source = builtins.toFile "nethermind-${nethermindName}-args" ''
+              ARGS="${serviceArgs.${nethermindName}.scriptArgs}"
+            '';
+            group = argsFromFile.group;
+            mode = argsFromFile.mode;
+          };
+      })
+    eachNethermind;
+
     # create a service for each instance
     systemd.services =
       mapAttrs' (
         nethermindName: let
           serviceName = "nethermind-${nethermindName}";
         in
           cfg: let
-            scriptArgs = let
-              # custom arg reducer for nethermind
-              argReducer = value:
-                if (isList value)
-                then concatStringsSep "," value
-                else if (isBool value)
-                then boolToString value
-                else toString value;
-
-              # remove modules from arguments
-              pathReducer = path: let
-                arg = concatStringsSep "." (lib.lists.remove "modules" path);
-              in "--${arg}";
-
-              # custom arg formatter for nethermind
-              argFormatter = {
-                path,
-                value,
-                argReducer,
-                pathReducer,
-                ...
-              }: let
-                arg = pathReducer path;
-              in "${arg} ${argReducer value}";
-
-              jwtSecret =
-                if cfg.args.modules.JsonRpc.JwtSecretFile != null
-                then "--JsonRpc.JwtSecretFile %d/jwtsecret"
-                else "";
-              datadir =
-                if cfg.args.datadir != null
-                then "--datadir ${cfg.args.datadir}"
-                else "--datadir %S/${serviceName}";
-
-              # generate flags
-              args = let
-                opts = import ./args.nix lib;
-              in
-                mkArgs {
-                  inherit pathReducer argReducer argFormatter opts;
-                  inherit (cfg) args;
-                };
-
-              # filter out certain args which need to be treated differently
-              specialArgs = ["--JsonRpc.JwtSecretFile"];
-              isNormalArg = name: (findFirst (arg: hasPrefix arg name) null specialArgs) == null;
-
-              filteredArgs = builtins.filter isNormalArg args;
-            in ''
-              ${datadir} \
-              ${jwtSecret} \
-              ${concatStringsSep " \\\n" filteredArgs} \
-              ${lib.escapeShellArgs cfg.extraArgs}
-            '';
+            inherit (serviceArgs."${nethermindName}") execStartCommand;
           in
             nameValuePair serviceName (mkIf cfg.enable {
               after = ["network.target"];
@@ -134,9 +85,10 @@ in {
               serviceConfig = mkMerge [
                 {
                   User = serviceName;
+                  EnvironmentFile = lib.mkIf cfg.argsFromFile.enable "/etc/ethereum/nethermind-${nethermindName}-args";
                   StateDirectory = serviceName;
                   MemoryDenyWriteExecute = false; # setting this option is incompatible with JIT
-                  ExecStart = "${cfg.package}/bin/nethermind ${scriptArgs}";
+                  ExecStart = execStartCommand;
                 }
                 baseServiceConfig
                 (mkIf (cfg.args.modules.JsonRpc.JwtSecretFile != null) {

modules/nethermind/options.nix

@@ -30,6 +30,22 @@
         description = "Open ports in the firewall for any enabled networking services";
       };
 
+      argsFromFile = {
+        enable = mkEnableOption (mdDoc "Create a file in the etc directory from which arguments can be modified");
+        group = mkOption {
+          type = types.str;
+          default = "";
+          example = "devops";
+          description = lib.mdDoc "Group which can modify the arguments file";
+        };
+        mode = mkOption {
+          type = types.str;
+          default = "0664";
+          example = "0060";
+          description = lib.mdDoc "Arguments file mode";
+        };
+      };
+
       # mixin backup options
       backup = let
         inherit (import ../backup/lib.nix lib) options;

modules/nethermind/service-args.nix

@@ -0,0 +1,75 @@
+{
+  lib,
+  pkgs,
+  ...
+}: let
+  modulesLib = import ../lib.nix lib;
+  inherit (builtins) isBool isList toString;
+  inherit (lib) boolToString concatStringsSep findFirst hasPrefix;
+  inherit (modulesLib) mkArgs;
+in {
+  argsCreate = serviceName: cfg: let
+    jwtSecret =
+      if cfg.args.modules.JsonRpc.JwtSecretFile != null
+      then "--JsonRpc.JwtSecretFile %d/jwtsecret"
+      else "";
+    datadir =
+      if cfg.args.datadir != null
+      then "--datadir ${cfg.args.datadir}"
+      else "--datadir %S/${serviceName}";
+  in rec {
+    scriptArgs = let
+      # custom arg reducer for nethermind
+      argReducer = value:
+        if (isList value)
+        then concatStringsSep "," value
+        else if (isBool value)
+        then boolToString value
+        else toString value;
+
+      # remove modules from arguments
+      pathReducer = path: let
+        arg = concatStringsSep "." (lib.lists.remove "modules" path);
+      in "--${arg}";
+
+      # custom arg formatter for nethermind
+      argFormatter = {
+        path,
+        value,
+        argReducer,
+        pathReducer,
+        ...
+      }: let
+        arg = pathReducer path;
+      in "${arg} ${argReducer value}";
+
+      # generate flags
+      args = let
+        opts = import ./args.nix lib;
+      in
+        mkArgs {
+          inherit pathReducer argReducer argFormatter opts;
+          inherit (cfg) args;
+        };
+
+      # filter out certain args which need to be treated differently
+      specialArgs = ["--JsonRpc.JwtSecretFile"];
+      isNormalArg = name: (findFirst (arg: hasPrefix arg name) null specialArgs) == null;
+
+      filteredArgs = builtins.filter isNormalArg args;
+    in ''
+      ${concatStringsSep " \\\n" filteredArgs} \
+      ${lib.escapeShellArgs cfg.extraArgs}
+    '';
+
+    systemdPathsArgs = ''
+      ${datadir} \
+      ${jwtSecret} \
+    '';
+
+    execStartCommand =
+      if cfg.argsFromFile.enable
+      then ''${cfg.package}/bin/nethermind ${systemdPathsArgs} $ARGS''
+      else ''${cfg.package}/bin/nethermind ${systemdPathsArgs} ${scriptArgs}'';
+  };
+}