Tobserver/modules/mempool.nix

{ config, pkgs, lib, ...}:
{
  virtualisation.oci-containers = {
    backend = "podman";

    containers = {
      mempool-db = {
        image = "mariadb:11";
        autoStart = true;
        environment = {
          MARIADB_DATABASE = "mempool";
          MARIADB_USER = "mempool";
          MARIADB_PASSWORD = "mempool";
          MARIADB_ROOT_PASSWORD = "root";
        };
        volumes = [
          "/srv/mempool/mysql:/var/lib/mysql"
        ];
      };

      mempool-backend = {
        image = "mempool/backend:latest";
        autoStart = true;
        dependsOn = [ "mempool-db" ];
        ports = [ "127.0.0.1:8999:8999" ];
        extraOptions = [
          "--add-host=host.containers.internal:host-gateway"
        ];
        environment = {
          MEMPOOL_NETWORK = "mainnet";
          MEMPOOL_BACKEND = "electrum";
          MEMPOOL_HTTP_PORT = "8999";

          ELECTRUM_HOST = "host.containers.internal";
          ELECTRUM_PORT = "50001";
          ELECTRUM_TLS_ENABLED = "false";

          CORE_RPC_HOST = "host.containers.internal";
          CORE_RPC_PORT = "8332";

          CORE_RPC_COOKIE = "true";
          CORE_RPC_COOKIE_PATH = "/bitcoin/.cookie";

          DATABASE_ENABLED = "true";
          DATABASE_HOST = "mempool-db";
          DATABASE_PORT = "3306";
          DATABASE_DATABASE = "mempool";
          DATABASE_USERNAME = "mempool";
          DATABASE_PASSWORD = "mempool";

          STATISTICS_ENABLED = "true";
        };
       volumes = [
         "/run/mempool/bitcoind.cookie:/bitcoin/.cookie:ro"
       ];
      };

      mempool-frontend = {
        image = "mempool/frontend:latest";
        autoStart = true;
        ports = [ "127.0.0.1:8998:8080" ];
        environment = {
          NGINX_HOSTNAME = "mempool.tobiasostner.de";
          NGINX_PORT = "443";
          NGINX_PROTOCOL = "https";
        };
      };
    };
  };

  systemd.tmpfiles.rules = lib.mkAfter [
    "d /run/mempool 0755 root root - -"
  ];

  # Copy cookie once
  systemd.services.mempool-cookie = {
    description = "Expose bitcoind cookie for mempool-backend";
    after = [ "bitcoind-mainnet.service" ];
    wants = [ "bitcoind-mainnet.service" ];

    serviceConfig = {
      Type = "oneshot";
      ExecStart = pkgs.writeShellScript "mempool-cookie" ''
        set -euo pipefail
        for i in $(seq 1 60); do
          if [ -f /var/lib/bitcoind/.cookie ]; then
            install -m 0644 -o root -g root /var/lib/bitcoind/.cookie /run/mempool/bitcoind.cookie
            exit 0
          fi
          sleep 1
        done
        echo "Cookie not found after 60s" >&2
        exit 1
    '';
    };
  };

  # Re-run the cookie copy whenever bitcoind rotates the cookie
  systemd.paths.mempool-cookie = {
    description = "Watch bitcoind cookie and refresh mempool copy";
    wantedBy = [ "multi-user.target" ];

    pathConfig = {
      PathChanged = "/var/lib/bitcoind/.cookie";
    };
  };

  # When the path triggers, it starts the service
  systemd.services.mempool-cookie.wantedBy = lib.mkForce [ ];
  systemd.paths.mempool-cookie.unitConfig = {
    Unit = "mempool-cookie.service";
  };

  systemd.services.podman-mempool-backend = {
    after = [ "mempool-cookie.service" ];
    wants = [ "mempool-cookie.service" ];
  };

  services.nginx = {
    appendHttpConfig = ''
      limit_req_zone $binary_remote_addr zone=mempool_api:10m rate=60r/m;
      limit_conn_zone $binary_remote_addr zone=mempool_ws:10m;
    '';

    virtualHosts."mempool.tobiasostner.de" = {
      enableACME = true;
      forceSSL = true;

      locations."/" = {
        proxyPass = "http://127.0.0.1:8998";
        extraConfig = ''
          proxy_set_header Host $host;
          proxy_set_header X-Real-IP $remote_addr;
          proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
          proxy_set_header X-Forwarded-Proto $scheme;
        '';
      };

      locations."/api/" = {
        proxyPass = "http://127.0.0.1:8999";
        extraConfig = ''
          limit_req zone=mempool_api burst=30 nodelay;

          proxy_http_version 1.1;
          proxy_set_header Host $host;
          proxy_set_header X-Real-IP $remote_addr;
          proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
          proxy_set_header X-Forwarded-Proto $scheme;

          proxy_connect_timeout 2s;
          proxy_read_timeout 60s;
          proxy_send_timeout 60s;
          proxy_next_upstream error timeout http_502 http_503 http_504;
          proxy_next_upstream_tries 3;
          proxy_next_upstream_timeout 10s;
        '';
      };

      locations."/api/v1/ws" = {
        proxyPass = "http://127.0.0.1:8999/api/v1/ws";
        proxyWebsockets = true;
        extraConfig = ''
          limit_conn mempool_ws 3;

          proxy_set_header Host $host;
          proxy_set_header X-Real-IP $remote_addr;
          proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
          proxy_set_header X-Forwarded-Proto $scheme;

          proxy_connect_timeout 2s;
          proxy_read_timeout 60s;
          proxy_send_timeout 60s;
          proxy_next_upstream error timeout http_502 http_503 http_504;
          proxy_next_upstream_tries 3;
          proxy_next_upstream_timeout 10s;
        '';
      };
    };
  };

  networking.firewall.interfaces."podman0".allowedTCPPorts = [ 8332 50001 ];
}