feat: introduce a Vault module for secrets management

Via a fork of the Linux Foundation, called OpenBao.

The module supports high availability but we only have one node for now.

Signed-off-by: Raito Bezarius <masterancpp@gmail.com>

services/default.nix

@@ -16,6 +16,7 @@
     ./buildbot
     ./newsletter
     ./s3-revproxy
+    ./vault
     ./extra-builders
   ];
 }

services/vault/default.nix

@@ -0,0 +1,65 @@
+{ config, lib, ... }:
+let
+  cfg = config.bagel.infra.vault;
+  inherit (lib) mkEnableOption mkOption mkIf concatStringsSep types;
+  mkPeerNode = fqdn: ''
+    retry_join {
+      leader_api_addr = "https://${fqdn}"
+      leader_tls_servername = "${fqdn}"
+    }
+  '';
+  wanAddress = if config.bagel.infra.self.wan.family == "inet6" then "[${config.bagel.infra.self.wan.address}]" else "${config.bagel.infra.self.wan.address}";
+in
+{
+  options.bagel.infra.vault = {
+    enable = mkEnableOption "the OpenBao (Vault fork) service";
+    peers = mkOption {
+      type = types.listOf types.str;
+      description = "List of FQDN that are peers of this service";
+    };
+  };
+
+  imports = [
+    ./module.nix
+  ];
+
+  config = mkIf cfg.enable {
+    networking.firewall.allowedTCPPorts = [
+      # NGINX HTTP API access
+      80
+      443
+      # mTLS backed cluster port
+      8201
+    ];
+    services.nginx = {
+      enable = true;
+      recommendedProxySettings = true;
+      virtualHosts."${config.networking.fqdn}" = {
+        enableACME = true;
+        forceSSL = true;
+
+        locations."/" = {
+          proxyPass = "http://127.0.0.1:8200";
+        };
+      };
+    };
+
+    services.openbao = {
+      enable = true;
+      storageBackend = "raft";
+      listenerExtraConfig = ''
+        cluster_address = "${wanAddress}:8201"
+      '';
+      storageConfig = ''
+        node_id = "${config.networking.fqdn}"
+
+        # Other nodes of the cluster.
+        ${concatStringsSep "\n" (map mkPeerNode cfg.peers)}
+      '';
+      extraConfig = ''
+        cluster_addr = "http://${config.networking.fqdn}:8201"
+        api_addr = "https://${config.networking.fqdn}"
+      '';
+    };
+  };
+}

services/vault/module.nix

@@ -0,0 +1,237 @@
+{ config, lib, options, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.openbao;
+  opt = options.services.openbao;
+
+  configFile = pkgs.writeText "openbao.hcl" ''
+    # vault in dev mode will refuse to start if its configuration sets listener
+    ${lib.optionalString (!cfg.dev) ''
+    listener "tcp" {
+      address = "${cfg.address}"
+      ${if (cfg.tlsCertFile == null || cfg.tlsKeyFile == null) then ''
+          tls_disable = "true"
+        '' else ''
+          tls_cert_file = "${cfg.tlsCertFile}"
+          tls_key_file = "${cfg.tlsKeyFile}"
+        ''}
+      ${cfg.listenerExtraConfig}
+    }
+    ''}
+    storage "${cfg.storageBackend}" {
+      ${optionalString (cfg.storagePath   != null) ''path = "${cfg.storagePath}"''}
+      ${optionalString (cfg.storageConfig != null) cfg.storageConfig}
+    }
+    ${optionalString (cfg.telemetryConfig != "") ''
+        telemetry {
+          ${cfg.telemetryConfig}
+        }
+      ''}
+    ${cfg.extraConfig}
+  '';
+
+  allConfigPaths = [configFile] ++ cfg.extraSettingsPaths;
+  configOptions = escapeShellArgs
+    (lib.optional cfg.dev "-dev" ++
+     lib.optional (cfg.dev && cfg.devRootTokenID != null) "-dev-root-token-id=${cfg.devRootTokenID}"
+      ++ (concatMap (p: ["-config" p]) allConfigPaths));
+
+in
+
+{
+  options = {
+    services.openbao = {
+      enable = mkEnableOption "OpenBao daemon";
+
+      package = mkPackageOption pkgs "openbao" { };
+
+      dev = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          In this mode, the Vault runs in-memory and starts unsealed. This option is not meant production but for development and testing i.e. for nixos tests.
+        '';
+      };
+
+      devRootTokenID = mkOption {
+        type = types.nullOr types.str;
+        default = null;
+        description = ''
+          Initial root token. This only applies when {option}`services.vault.dev` is true
+        '';
+      };
+
+      address = mkOption {
+        type = types.str;
+        default = "127.0.0.1:8200";
+        description = "The name of the ip interface to listen to";
+      };
+
+      tlsCertFile = mkOption {
+        type = types.nullOr types.str;
+        default = null;
+        example = "/path/to/your/cert.pem";
+        description = "TLS certificate file. TLS will be disabled unless this option is set";
+      };
+
+      tlsKeyFile = mkOption {
+        type = types.nullOr types.str;
+        default = null;
+        example = "/path/to/your/key.pem";
+        description = "TLS private key file. TLS will be disabled unless this option is set";
+      };
+
+      listenerExtraConfig = mkOption {
+        type = types.lines;
+        default = ''
+          tls_min_version = "tls12"
+        '';
+        description = "Extra text appended to the listener section.";
+      };
+
+      storageBackend = mkOption {
+        type = types.enum [ "inmem" "file" "consul" "zookeeper" "s3" "azure" "dynamodb" "etcd" "mssql" "mysql" "postgresql" "swift" "gcs" "raft" ];
+        default = "inmem";
+        description = "The name of the type of storage backend";
+      };
+
+      storagePath = mkOption {
+        type = types.nullOr types.path;
+        default = if cfg.storageBackend == "file" || cfg.storageBackend == "raft" then "/var/lib/vault" else null;
+        defaultText = literalExpression ''
+          if config.${opt.storageBackend} == "file" || cfg.storageBackend == "raft"
+          then "/var/lib/vault"
+          else null
+        '';
+        description = "Data directory for file backend";
+      };
+
+      storageConfig = mkOption {
+        type = types.nullOr types.lines;
+        default = null;
+        description = ''
+          HCL configuration to insert in the storageBackend section.
+
+          Confidential values should not be specified here because this option's
+          value is written to the Nix store, which is publicly readable.
+          Provide credentials and such in a separate file using
+          [](#opt-services.vault.extraSettingsPaths).
+        '';
+      };
+
+      telemetryConfig = mkOption {
+        type = types.lines;
+        default = "";
+        description = "Telemetry configuration";
+      };
+
+      extraConfig = mkOption {
+        type = types.lines;
+        default = "";
+        description = "Extra text appended to {file}`vault.hcl`.";
+      };
+
+      extraSettingsPaths = mkOption {
+        type = types.listOf types.path;
+        default = [];
+        description = ''
+          Configuration files to load besides the immutable one defined by the NixOS module.
+          This can be used to avoid putting credentials in the Nix store, which can be read by any user.
+
+          Each path can point to a JSON- or HCL-formatted file, or a directory
+          to be scanned for files with `.hcl` or
+          `.json` extensions.
+
+          To upload the confidential file with NixOps, use for example:
+
+          ```
+          # https://releases.nixos.org/nixops/latest/manual/manual.html#opt-deployment.keys
+          deployment.keys."vault.hcl" = let db = import ./db-credentials.nix; in {
+            text = ${"''"}
+              storage "postgresql" {
+                connection_url = "postgres://''${db.username}:''${db.password}@host.example.com/exampledb?sslmode=verify-ca"
+              }
+            ${"''"};
+            user = "vault";
+          };
+          services.vault.extraSettingsPaths = ["/run/keys/vault.hcl"];
+          services.vault.storageBackend = "postgresql";
+          users.users.vault.extraGroups = ["keys"];
+          ```
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    nixpkgs.overlays = [ (self: super: {
+      openbao = super.callPackage ./package.nix { };
+    }) ];
+
+    environment.systemPackages = [
+      pkgs.openbao
+    ];
+
+    assertions = [
+      {
+        assertion = cfg.storageBackend == "inmem" -> (cfg.storagePath == null && cfg.storageConfig == null);
+        message = ''The "inmem" storage expects no services.vault.storagePath nor services.vault.storageConfig'';
+      }
+      {
+        assertion = (
+          (cfg.storageBackend == "file" -> (cfg.storagePath != null && cfg.storageConfig == null)) &&
+          (cfg.storagePath != null -> (cfg.storageBackend == "file" || cfg.storageBackend == "raft"))
+        );
+        message = ''You must set services.vault.storagePath only when using the "file" or "raft" backend'';
+      }
+    ];
+
+    users.users.openbao = {
+      name = "openbao";
+      group = "openbao";
+      uid = config.ids.uids.vault;
+      description = "OpenBao daemon user";
+    };
+    users.groups.openbao.gid = config.ids.gids.vault;
+
+    systemd.tmpfiles.rules = optional (cfg.storagePath != null)
+      "d '${cfg.storagePath}' 0700 openbao openbao - -";
+
+    systemd.services.openbao = {
+      description = "OpenBao server daemon";
+
+      wantedBy = ["multi-user.target"];
+      after = [ "network.target" ]
+           ++ optional (config.services.consul.enable && cfg.storageBackend == "consul") "consul.service";
+
+      restartIfChanged = false; # do not restart on "nixos-rebuild switch". It would seal the storage and disrupt the clients.
+
+      startLimitIntervalSec = 60;
+      startLimitBurst = 3;
+      serviceConfig = {
+        User = "openbao";
+        Group = "openbao";
+        ExecStart = "${lib.getExe cfg.package} server ${configOptions}";
+        ExecReload = "${pkgs.coreutils}/bin/kill -SIGHUP $MAINPID";
+        StateDirectory = "vault";
+        # In `dev` mode vault will put its token here
+        Environment = lib.optional (cfg.dev) "HOME=/var/lib/vault";
+        PrivateDevices = true;
+        PrivateTmp = true;
+        ProtectSystem = "full";
+        ProtectHome = "read-only";
+        AmbientCapabilities = "cap_ipc_lock";
+        NoNewPrivileges = true;
+        LimitCORE = 0;
+        KillSignal = "SIGINT";
+        TimeoutStopSec = "30s";
+        Restart = "on-failure";
+      };
+
+      unitConfig.RequiresMountsFor = optional (cfg.storagePath != null) cfg.storagePath;
+    };
+  };
+
+}

services/vault/package.nix

@@ -0,0 +1,51 @@
+{ stdenv, lib, fetchFromGitHub, buildGoModule, installShellFiles, nixosTests
+, makeWrapper
+, gawk
+, glibc
+}:
+
+buildGoModule rec {
+  pname = "openbao";
+  version = "2.0.2";
+
+  src = fetchFromGitHub {
+    owner = "openbao";
+    repo = "openbao";
+    rev = "v${version}";
+    hash = "sha256-7Dqrw00wjI/VCahY1+ANBMq9nPUQlb94HiBB3CKyhSQ=";
+  };
+
+  vendorHash = "sha256-qojDPhdCqnYCAFo5sc9mWyQxvHc/p/a1LYdW7MbOO5w=";
+
+  subPackages = [ "." ];
+
+  nativeBuildInputs = [ installShellFiles makeWrapper ];
+
+  tags = [ "openbao" ];
+
+  ldflags = [
+    "-s" "-w"
+    "-X github.com/openbao/openbao/sdk/version.GitCommit=${src.rev}"
+    "-X github.com/openbao/openbao/sdk/version.Version=${version}"
+    "-X github.com/openbao/openbao/sdk/version.VersionPrerelease="
+  ];
+
+  postInstall = ''
+    echo "complete -C $out/bin/openbao openbao" > openbao.bash
+    installShellCompletion openbao.bash
+  '' + lib.optionalString stdenv.isLinux ''
+    wrapProgram $out/bin/openbao \
+      --prefix PATH ${lib.makeBinPath [ gawk glibc ]}
+  '';
+
+  # passthru.tests = { inherit (nixosTests) vault vault-postgresql vault-dev vault-agent; };
+
+  meta = with lib; {
+    homepage = "https://openbao.org/";
+    description = "Tool for managing secrets";
+    changelog = "https://github.com/openbao/openbao/blob/v${version}/CHANGELOG.md";
+    license = licenses.mpl20;
+    mainProgram = "openbao";
+    maintainers = with maintainers; [ raitobezarius ];
+  };
+}