nixpkgs/nixos/modules/services/security/hologram-server.nix

{pkgs, config, lib, ...}:

with lib;

let
  cfg = config.services.hologram-server;

  cfgFile = pkgs.writeText "hologram-server.json" (builtins.toJSON {
    ldap = {
      host = cfg.ldapHost;
      bind = {
        dn       = cfg.ldapBindDN;
        password = cfg.ldapBindPassword;
      };
      insecureldap    = cfg.ldapInsecure;
      userattr        = cfg.ldapUserAttr;
      baseDN          = cfg.ldapBaseDN;
      enableldapRoles = cfg.enableLdapRoles;
      roleAttr        = cfg.roleAttr;
      groupClassAttr  = cfg.groupClassAttr;
    };
    aws = {
      account     = cfg.awsAccount;
      defaultrole = cfg.awsDefaultRole;
    };
    stats        = cfg.statsAddress;
    listen       = cfg.listenAddress;
    cachetimeout = cfg.cacheTimeoutSeconds;
  });
in {
  options = {
    services.hologram-server = {
      enable = mkOption {
        type = types.bool;
        default = false;
        description = "Whether to enable the Hologram server for AWS instance credentials";
      };

      listenAddress = mkOption {
        type        = types.str;
        default     = "0.0.0.0:3100";
        description = "Address and port to listen on";
      };

      ldapHost = mkOption {
        type        = types.str;
        description = "Address of the LDAP server to use";
      };

      ldapInsecure = mkOption {
        type        = types.bool;
        default     = false;
        description = "Whether to connect to LDAP over SSL or not";
      };

      ldapUserAttr = mkOption {
        type        = types.str;
        default     = "cn";
        description = "The LDAP attribute for usernames";
      };

      ldapBaseDN = mkOption {
        type        = types.str;
        description = "The base DN for your Hologram users";
      };

      ldapBindDN = mkOption {
        type        = types.str;
        description = "DN of account to use to query the LDAP server";
      };

      ldapBindPassword = mkOption {
        type        = types.str;
        description = "Password of account to use to query the LDAP server";
      };

      enableLdapRoles = mkOption {
        type        = types.bool;
        default     = false;
        description = "Whether to assign user roles based on the user's LDAP group memberships";
      };

      groupClassAttr = mkOption {
        type = types.str;
        default = "groupOfNames";
        description = "The objectclass attribute to search for groups when enableLdapRoles is true";
      };

      roleAttr = mkOption {
        type        = types.str;
        default     = "businessCategory";
        description = "Which LDAP group attribute to search for authorized role ARNs";
      };

      awsAccount = mkOption {
        type        = types.str;
        description = "AWS account number";
      };

      awsDefaultRole = mkOption {
        type        = types.str;
        description = "AWS default role";
      };

      statsAddress = mkOption {
        type        = types.str;
        default     = "";
        description = "Address of statsd server";
      };

      cacheTimeoutSeconds = mkOption {
        type        = types.int;
        default     = 3600;
        description = "How often (in seconds) to refresh the LDAP cache";
      };
    };
  };

  config = mkIf cfg.enable {
    systemd.services.hologram-server = {
      description = "Provide EC2 instance credentials to machines outside of EC2";
      after       = [ "network.target" ];
      wantedBy    = [ "multi-user.target" ];

      serviceConfig = {
        ExecStart = "${pkgs.hologram.bin}/bin/hologram-server --debug --conf ${cfgFile}";
      };
    };
  };
}