nixos/{consul-template,vault-agent}: init

nixos/doc/manual/release-notes/rl-2305.section.md

···
 
 - [keyd](https://github.com/rvaiya/keyd), a key remapping daemon for linux. Available as [services.keyd](#opt-services.keyd.enable).
 
+- [consul-template](https://github.com/hashicorp/consul-template/), a template rendering, notifier, and supervisor for HashiCorp Consul and Vault data. Available as [services.consul-template](#opt-services.consul-template.instances).
+
+- [vault-agent](https://developer.hashicorp.com/vault/docs/agent), a template rendering and API auth proxy for HashiCorp Vault, similar to `consul-template`. Available as [services.vault-agent](#opt-services.vault-agent.instances).
+
 - [v2rayA](https://v2raya.org), a Linux web GUI client of Project V which supports V2Ray, Xray, SS, SSR, Trojan and Pingtunnel. Available as [services.v2raya](options.html#opt-services.v2raya.enable).
 
 - [wstunnel](https://github.com/erebe/wstunnel), a proxy tunnelling arbitrary TCP or UDP traffic through a WebSocket connection. Instances may be configured via [services.wstunnel](options.html#opt-services.wstunnel.enable).

nixos/modules/module-list.nix

···
   ./services/security/torsocks.nix
   ./services/security/usbguard.nix
   ./services/security/vault.nix
+  ./services/security/vault-agent.nix
   ./services/security/vaultwarden/default.nix
   ./services/security/yubikey-agent.nix
   ./services/system/automatic-timezoned.nix

nixos/modules/services/security/vault-agent.nix

···
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  format = pkgs.formats.json { };
+  commonOptions = { pkgName, flavour ? pkgName }: mkOption {
+    default = { };
+    description = mdDoc ''
+      Attribute set of ${flavour} instances.
+      Creates independent `${flavour}-''${name}.service` systemd units for each instance defined here.
+    '';
+    type = with types; attrsOf (submodule ({ name, ... }: {
+      options = {
+        enable = mkEnableOption (mdDoc "this ${flavour} instance") // { default = true; };
+
+        package = mkPackageOptionMD pkgs pkgName { };
+
+        user = mkOption {
+          type = types.str;
+          default = "root";
+          description = mdDoc ''
+            User under which this instance runs.
+          '';
+        };
+
+        group = mkOption {
+          type = types.str;
+          default = "root";
+          description = mdDoc ''
+            Group under which this instance runs.
+          '';
+        };
+
+        settings = mkOption {
+          type = types.submodule {
+            freeformType = format.type;
+
+            options = {
+              pid_file = mkOption {
+                default = "/run/${flavour}/${name}.pid";
+                type = types.str;
+                description = mdDoc ''
+                  Path to use for the pid file.
+                '';
+              };
+
+              template = mkOption {
+                default = [ ];
+                type = with types; listOf (attrsOf anything);
+                description =
+                  let upstreamDocs =
+                    if flavour == "vault-agent"
+                    then "https://developer.hashicorp.com/vault/docs/agent/template"
+                    else "https://github.com/hashicorp/consul-template/blob/main/docs/configuration.md#templates";
+                  in
+                  mdDoc ''
+                    Template section of ${flavour}.
+                    Refer to <${upstreamDocs}> for supported values.
+                  '';
+              };
+            };
+          };
+
+          default = { };
+
+          description =
+            let upstreamDocs =
+              if flavour == "vault-agent"
+              then "https://developer.hashicorp.com/vault/docs/agent#configuration-file-options"
+              else "https://github.com/hashicorp/consul-template/blob/main/docs/configuration.md#configuration-file";
+            in
+            mdDoc ''
+              Free-form settings written directly to the `config.json` file.
+              Refer to <${upstreamDocs}> for supported values.
+
+              ::: {.note}
+              Resulting format is JSON not HCL.
+              Refer to <https://www.hcl2json.com/> if you are unsure how to convert HCL options to JSON.
+              :::
+            '';
+        };
+      };
+    }));
+  };
+
+  createAgentInstance = { instance, name, flavour }:
+    let
+      configFile = format.generate "${name}.json" instance.settings;
+    in
+    mkIf (instance.enable) {
+      description = "${flavour} daemon - ${name}";
+      wantedBy = [ "multi-user.target" ];
+      after = [ "network.target" ];
+      path = [ pkgs.getent ];
+      startLimitIntervalSec = 60;
+      startLimitBurst = 3;
+      serviceConfig = {
+        User = instance.user;
+        Group = instance.group;
+        RuntimeDirectory = flavour;
+        ExecStart = "${getExe instance.package} ${optionalString ((getName instance.package) == "vault") "agent"} -config ${configFile}";
+        ExecReload = "${pkgs.coreutils}/bin/kill -SIGHUP $MAINPID";
+        KillSignal = "SIGINT";
+        TimeoutStopSec = "30s";
+        Restart = "on-failure";
+      };
+    };
+in
+{
+  options = {
+    services.consul-template.instances = commonOptions { pkgName = "consul-template"; };
+    services.vault-agent.instances = commonOptions { pkgName = "vault"; flavour = "vault-agent"; };
+  };
+
+  config = mkMerge (map
+    (flavour:
+      let cfg = config.services.${flavour}; in
+      mkIf (cfg.instances != { }) {
+        systemd.services = mapAttrs'
+          (name: instance: nameValuePair "${flavour}-${name}" (createAgentInstance { inherit name instance flavour; }))
+          cfg.instances;
+      })
+    [ "consul-template" "vault-agent" ]);
+
+  meta.maintainers = with maintainers; [ indeednotjames tcheronneau ];
+}
+