From cf90db8b708b01909ecdc1ca1f579db1f49005ce Mon Sep 17 00:00:00 2001
From: Bouke van der Bijl <i@bou.ke>
Date: Tue, 14 Mar 2023 14:15:17 +0100
Subject: [PATCH] nixiso/opentelemetry-collector: init

---
 nixos/modules/module-list.nix                 |  1 +
 .../monitoring/opentelemetry-collector.nix    | 73 +++++++++++++++++++
 .../misc/opentelemetry-collector/default.nix  |  1 +
 3 files changed, 75 insertions(+)
 create mode 100644 nixos/modules/services/monitoring/opentelemetry-collector.nix

diff --git a/nixos/modules/module-list.nix b/nixos/modules/module-list.nix
index 314d67419b7..9457ac15ab5 100644
--- a/nixos/modules/module-list.nix
+++ b/nixos/modules/module-list.nix
@@ -733,6 +733,7 @@
   ./services/monitoring/munin.nix
   ./services/monitoring/nagios.nix
   ./services/monitoring/netdata.nix
+  ./services/monitoring/opentelemetry-collector.nix
   ./services/monitoring/parsedmarc.nix
   ./services/monitoring/prometheus/alertmanager.nix
   ./services/monitoring/prometheus/default.nix
diff --git a/nixos/modules/services/monitoring/opentelemetry-collector.nix b/nixos/modules/services/monitoring/opentelemetry-collector.nix
new file mode 100644
index 00000000000..1d211b68977
--- /dev/null
+++ b/nixos/modules/services/monitoring/opentelemetry-collector.nix
@@ -0,0 +1,73 @@
+{ config, lib, pkgs, ... }:
+
+let
+  inherit (lib) mkEnableOption mkIf mkOption types getExe;
+
+  cfg = config.services.opentelemetry-collector;
+  opentelemetry-collector = cfg.package;
+
+  settingsFormat = pkgs.formats.yaml {};
+in {
+  options.services.opentelemetry-collector = {
+    enable = mkEnableOption (lib.mdDoc "Opentelemetry Collector");
+
+    package = mkOption {
+      type = types.package;
+      default = pkgs.opentelemetry-collector;
+      defaultText = lib.literalExpression "pkgs.opentelemetry-collector";
+      description = lib.mdDoc "The opentelemetry-collector package to use.";
+    };
+
+    settings = mkOption {
+      type = settingsFormat.type;
+      default = {};
+      description = lib.mdDoc ''
+        Specify the configuration for Opentelemetry Collector in Nix.
+
+        See https://opentelemetry.io/docs/collector/configuration/ for available options.
+      '';
+    };
+
+    configFile = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = lib.mdDoc ''
+        Specify a path to a configuration file that Opentelemetry Collector should use.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    assertions = [{
+      assertion = (
+        (cfg.settings == {}) != (cfg.configFile == null)
+      );
+      message  = ''
+        Please specify a configuration for Opentelemetry Collector with either
+        'services.opentelemetry-collector.settings' or
+        'services.opentelemetry-collector.configFile'.
+      '';
+    }];
+
+    systemd.services.opentelemetry-collector = {
+      description = "Opentelemetry Collector Service Daemon";
+      wantedBy = [ "multi-user.target" ];
+
+      serviceConfig = let
+        conf = if cfg.configFile == null
+               then settingsFormat.generate "config.yaml" cfg.settings
+               else cfg.configFile;
+      in
+      {
+        ExecStart = "${getExe opentelemetry-collector} --config=file:${conf}";
+        DynamicUser = true;
+        Restart = "always";
+        ProtectSystem = "full";
+        DevicePolicy = "closed";
+        NoNewPrivileges = true;
+        WorkingDirectory = "/var/lib/opentelemetry-collector";
+        StateDirectory = "opentelemetry-collector";
+      };
+    };
+  };
+}
diff --git a/pkgs/tools/misc/opentelemetry-collector/default.nix b/pkgs/tools/misc/opentelemetry-collector/default.nix
index e9448f84fd2..ce412ec844f 100644
--- a/pkgs/tools/misc/opentelemetry-collector/default.nix
+++ b/pkgs/tools/misc/opentelemetry-collector/default.nix
@@ -48,5 +48,6 @@ buildGoModule rec {
     '';
     license = licenses.asl20;
     maintainers = with maintainers; [ uri-canva jk ];
+    mainProgram = "otelcorecol";
   };
 }