nix-hermes-agent/module.nix
Ciphercat 3dd03ba2ae feat: declarative NixOS module following nix-openclaw patterns
- Deep-merge config attrset → cli-config.yaml (like nix-openclaw's JSON config)
- Declarative documents option (SOUL.md, AGENTS.md, USER.md — inline or file paths)
- MCP servers as structured Nix options (merged into config)
- Environment files for secrets (systemd EnvironmentFile, outside Nix store)
- Non-secret environment vars (separate from secrets)
- Proper tmpfiles rules, activation scripts for config + document linking
- systemd hardening (NoNewPrivileges, ProtectSystem, PrivateTmp)
- Comprehensive README with full usage examples
2026-03-15 23:59:09 +00:00

332 lines
12 KiB
Nix

self:
{ config, lib, pkgs, ... }:
let
cfg = config.services.hermes-agent;
hermes-agent = self.packages.${pkgs.system}.hermes-agent;
# Deep-merge config type (same pattern as nix-openclaw)
deepConfigType = lib.types.mkOptionType {
name = "hermes-config-attrs";
description = "Hermes YAML config (attrset), merged deeply via lib.recursiveUpdate.";
check = builtins.isAttrs;
merge = _loc: defs: lib.foldl' lib.recursiveUpdate { } (map (d: d.value) defs);
};
# Convert Nix attrset → YAML via JSON intermediary
# (Hermes reads YAML but YAML is a superset of JSON, so JSON works)
configJson = builtins.toJSON cfg.config;
generatedConfigFile = pkgs.writeText "cli-config.yaml" configJson;
configFile = if cfg.configFile != null then cfg.configFile else generatedConfigFile;
# Generate .env file from environment attrset (non-secret env vars)
envFileContent = lib.concatStringsSep "\n" (
lib.mapAttrsToList (k: v: "${k}=${v}") cfg.environment
);
generatedEnvFile = pkgs.writeText "hermes-env" envFileContent;
# Document files → symlinked into workspace
documentDerivation = pkgs.runCommand "hermes-documents" { } (
''
mkdir -p $out
'' + lib.concatStringsSep "\n" (
lib.mapAttrsToList (name: value:
if builtins.isPath value || lib.isStorePath value
then "cp ${value} $out/${name}"
else "cat > $out/${name} <<'HERMES_DOC_EOF'\n${value}\nHERMES_DOC_EOF"
) cfg.documents
)
);
in
{
options.services.hermes-agent = with lib; {
enable = mkEnableOption "Hermes Agent gateway service";
# ── Package ──────────────────────────────────────────────────────────
package = mkOption {
type = types.package;
default = hermes-agent;
description = "The hermes-agent package to use.";
};
# ── Service identity ─────────────────────────────────────────────────
unitName = mkOption {
type = types.str;
default = "hermes-agent";
description = "systemd unit name (<unitName>.service).";
};
user = mkOption {
type = types.str;
default = "hermes";
description = "System user running the gateway.";
};
group = mkOption {
type = types.str;
default = "hermes";
description = "System group running the gateway.";
};
createUser = mkOption {
type = types.bool;
default = true;
description = "Create the user/group automatically.";
};
# ── Directories ──────────────────────────────────────────────────────
stateDir = mkOption {
type = types.str;
default = "/var/lib/hermes";
description = "State directory (HERMES_HOME base). Contains .hermes/ subdir.";
};
workingDirectory = mkOption {
type = types.str;
default = "${cfg.stateDir}/workspace";
defaultText = literalExpression ''"''${cfg.stateDir}/workspace"'';
description = "Working directory for the agent (MESSAGING_CWD).";
};
# ── Config (declarative YAML) ────────────────────────────────────────
configFile = mkOption {
type = types.nullOr types.path;
default = null;
description = ''
Path to an existing cli-config.yaml. If set, takes precedence over
the declarative `config` option.
'';
};
config = mkOption {
type = deepConfigType;
default = { };
description = ''
Declarative Hermes config (attrset). Deep-merged across module definitions
and rendered as cli-config.yaml. See upstream cli-config.yaml.example for
all available keys.
'';
example = literalExpression ''
{
model = {
default = "anthropic/claude-sonnet-4-20250514";
provider = "openrouter";
};
terminal = {
backend = "local";
timeout = 180;
};
agent = {
max_turns = 60;
reasoning_effort = "medium";
};
memory = {
memory_enabled = true;
user_profile_enabled = true;
};
toolsets = [ "all" ];
}
'';
};
# ── Secrets / environment ────────────────────────────────────────────
environmentFiles = mkOption {
type = types.listOf types.str;
default = [ ];
description = ''
Paths to environment files containing secrets (API keys, tokens).
These are passed as systemd EnvironmentFile= entries.
Use leading '-' to ignore missing files.
Example file contents:
ANTHROPIC_API_KEY=sk-ant-...
OPENROUTER_API_KEY=sk-or-...
TELEGRAM_TOKEN=123456:ABC...
'';
};
environment = mkOption {
type = types.attrsOf types.str;
default = { };
description = ''
Non-secret environment variables for Hermes. These are written to
an env file (visible in the Nix store do NOT put secrets here).
Use `environmentFiles` for secrets.
'';
example = literalExpression ''
{
LLM_MODEL = "anthropic/claude-opus-4.6";
MESSAGING_CWD = "/var/lib/hermes/workspace";
}
'';
};
# ── Documents (SOUL.md, AGENTS.md, etc.) ─────────────────────────────
documents = mkOption {
type = types.attrsOf (types.either types.str types.path);
default = { };
description = ''
Workspace document files. Keys are filenames, values are either
inline strings or paths to files. These are symlinked into the
workspace directory on activation.
'';
example = literalExpression ''
{
"SOUL.md" = '''
# SOUL.md
You are a helpful AI assistant.
''';
"AGENTS.md" = ./my-agents.md;
"USER.md" = '''
# USER.md
Name: Fay
''';
}
'';
};
# ── Service behavior ─────────────────────────────────────────────────
logPath = mkOption {
type = types.str;
default = "${cfg.stateDir}/logs/gateway.log";
defaultText = literalExpression ''"''${cfg.stateDir}/logs/gateway.log"'';
description = "Log file path.";
};
extraArgs = mkOption {
type = types.listOf types.str;
default = [ ];
description = "Extra command-line arguments for `hermes gateway`.";
};
execStart = mkOption {
type = types.nullOr types.str;
default = null;
description = "Override ExecStart command. If unset, runs: hermes gateway.";
};
extraPackages = mkOption {
type = types.listOf types.package;
default = [ ];
description = "Extra packages to make available on PATH.";
};
restart = mkOption {
type = types.str;
default = "always";
description = "systemd Restart= policy.";
};
restartSec = mkOption {
type = types.int;
default = 5;
description = "systemd RestartSec= value.";
};
# ── MCP servers ──────────────────────────────────────────────────────
mcpServers = mkOption {
type = types.attrsOf (types.submodule {
options = {
command = mkOption { type = types.str; description = "MCP server command."; };
args = mkOption { type = types.listOf types.str; default = [ ]; };
env = mkOption { type = types.attrsOf types.str; default = { }; };
timeout = mkOption { type = types.nullOr types.int; default = null; };
};
});
default = { };
description = "MCP server configurations (merged into config.mcp_servers).";
};
};
config = lib.mkIf cfg.enable {
# ── Merge MCP servers into config ────────────────────────────────────
services.hermes-agent.config = lib.mkIf (cfg.mcpServers != { }) {
mcp_servers = lib.mapAttrs (_name: srv:
{ inherit (srv) command args; }
// lib.optionalAttrs (srv.env != { }) { inherit (srv) env; }
// lib.optionalAttrs (srv.timeout != null) { inherit (srv) timeout; }
) cfg.mcpServers;
};
# ── User / group ─────────────────────────────────────────────────────
users.groups.${cfg.group} = lib.mkIf cfg.createUser { };
users.users.${cfg.user} = lib.mkIf cfg.createUser {
isSystemUser = true;
group = cfg.group;
home = cfg.stateDir;
createHome = true;
shell = pkgs.bashInteractive;
};
# ── Directories ──────────────────────────────────────────────────────
systemd.tmpfiles.rules = [
"d ${cfg.stateDir} 0750 ${cfg.user} ${cfg.group} - -"
"d ${cfg.stateDir}/.hermes 0750 ${cfg.user} ${cfg.group} - -"
"d ${cfg.workingDirectory} 0750 ${cfg.user} ${cfg.group} - -"
"d ${builtins.dirOf cfg.logPath} 0750 ${cfg.user} ${cfg.group} - -"
];
# ── Activation: link config + documents into state dir ───────────────
system.activationScripts."hermes-agent-setup" = lib.stringAfter [ "users" ] ''
# Link config file
install -o ${cfg.user} -g ${cfg.group} -m 0640 -D ${configFile} ${cfg.stateDir}/.hermes/cli-config.yaml
# Link documents into workspace
${lib.concatStringsSep "\n" (lib.mapAttrsToList (name: _value: ''
install -o ${cfg.user} -g ${cfg.group} -m 0644 ${documentDerivation}/${name} ${cfg.workingDirectory}/${name}
'') cfg.documents)}
'';
# ── systemd service ──────────────────────────────────────────────────
systemd.services.${cfg.unitName} = {
description = "Hermes Agent Gateway";
wantedBy = [ "multi-user.target" ];
after = [ "network-online.target" ];
wants = [ "network-online.target" ];
environment = {
HOME = cfg.stateDir;
HERMES_HOME = "${cfg.stateDir}/.hermes";
MESSAGING_CWD = cfg.workingDirectory;
};
serviceConfig = {
User = cfg.user;
Group = cfg.group;
WorkingDirectory = cfg.workingDirectory;
EnvironmentFile =
[ generatedEnvFile ]
++ cfg.environmentFiles;
ExecStart =
if cfg.execStart != null then cfg.execStart
else lib.concatStringsSep " " ([
"${cfg.package}/bin/hermes"
"gateway"
] ++ cfg.extraArgs);
Restart = cfg.restart;
RestartSec = cfg.restartSec;
StandardOutput = "append:${cfg.logPath}";
StandardError = "append:${cfg.logPath}";
# Hardening
NoNewPrivileges = true;
ProtectSystem = "strict";
ProtectHome = false;
ReadWritePaths = [ cfg.stateDir ];
PrivateTmp = true;
};
path = [
cfg.package
pkgs.bash
pkgs.coreutils
pkgs.git
] ++ cfg.extraPackages;
};
};
}