{ hosts, pkgs, ... }:
let
  # https://github.com/element-hq/synapse/tree/master/contrib/prometheus/
  synapseRules = pkgs.fetchurl {
    url = "https://raw.githubusercontent.com/element-hq/synapse/refs/heads/master/contrib/prometheus/synapse-v2.rules";
    hash = "sha256-WldlBdCMzul49OlFhJMsrx4MYFakHTa36Y9HnV22EwI=";
  };
in
{
  services.prometheus = {
    enable = true;
    retentionTime = "90d";
    ruleFiles = [ synapseRules ];
    scrapeConfigs = [
      {
        job_name = "node";
        static_configs = builtins.map (name: {
          targets = [
            "${name}.${hosts.${name}.site}.grzb.de:9100"
          ];
          labels = {
            host = "${name}.${hosts.${name}.site}.grzb.de";
          };
        }) (builtins.attrNames hosts);
      }
      {
        job_name = "synapse";
        scrape_interval = "15s";
        metrics_path = "/_synapse/metrics";
        static_configs = [{
          targets = [ "matrix.vs.grzb.de:9000" ];
        }];
      }
    ];
  };
}