diff --git a/nixos/modules/services/security/vault.nix b/nixos/modules/services/security/vault.nix
index 64622454b9d..5a20f6413b1 100644
--- a/nixos/modules/services/security/vault.nix
+++ b/nixos/modules/services/security/vault.nix
@@ -27,6 +27,11 @@ let
       ''}
     ${cfg.extraConfig}
   '';
+
+  allConfigPaths = [configFile] ++ cfg.extraSettingsPaths;
+
+  configOptions = escapeShellArgs (concatMap (p: ["-config" p]) allConfigPaths);
+
 in
 
 {
@@ -84,7 +89,14 @@ in
       storageConfig = mkOption {
         type = types.nullOr types.lines;
         default = null;
-        description = "Storage configuration";
+        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
+          <xref linkend="opt-services.vault.extraSettingsPaths"/>.
+        '';
       };
 
       telemetryConfig = mkOption {
@@ -98,6 +110,36 @@ in
         default = "";
         description = "Extra text appended to <filename>vault.hcl</filename>.";
       };
+
+      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 <literal>.hcl</literal> or
+          <literal>.json</literal> extensions.
+
+          To upload the confidential file with NixOps, use for example:
+
+          <programlisting><![CDATA[
+          # 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"];
+          ]]></programlisting>
+        '';
+      };
     };
   };
 
@@ -136,7 +178,7 @@ in
       serviceConfig = {
         User = "vault";
         Group = "vault";
-        ExecStart = "${cfg.package}/bin/vault server -config ${configFile}";
+        ExecStart = "${cfg.package}/bin/vault server ${configOptions}";
         ExecReload = "${pkgs.coreutils}/bin/kill -SIGHUP $MAINPID";
         PrivateDevices = true;
         PrivateTmp = true;
diff --git a/nixos/tests/all-tests.nix b/nixos/tests/all-tests.nix
index 523d3c051e0..246ad754827 100644
--- a/nixos/tests/all-tests.nix
+++ b/nixos/tests/all-tests.nix
@@ -407,6 +407,7 @@ in
   uwsgi = handleTest ./uwsgi.nix {};
   v2ray = handleTest ./v2ray.nix {};
   vault = handleTest ./vault.nix {};
+  vault-postgresql = handleTest ./vault-postgresql.nix {};
   vector = handleTest ./vector.nix {};
   victoriametrics = handleTest ./victoriametrics.nix {};
   virtualbox = handleTestOn ["x86_64-linux"] ./virtualbox.nix {};
diff --git a/nixos/tests/vault-postgresql.nix b/nixos/tests/vault-postgresql.nix
new file mode 100644
index 00000000000..daa71976338
--- /dev/null
+++ b/nixos/tests/vault-postgresql.nix
@@ -0,0 +1,70 @@
+/* This test checks that
+    - multiple config files can be loaded
+    - the storage backend can be in a file outside the nix store
+      as is required for security (required because while confidentiality is
+      always covered, availability isn't)
+    - the postgres integration works
+ */
+import ./make-test-python.nix ({ pkgs, ... }:
+{
+  name = "vault-postgresql";
+  meta = with pkgs.stdenv.lib.maintainers; {
+    maintainers = [ lnl7 roberth ];
+  };
+  machine = { lib, pkgs, ... }: {
+    virtualisation.memorySize = 512;
+    environment.systemPackages = [ pkgs.vault ];
+    environment.variables.VAULT_ADDR = "http://127.0.0.1:8200";
+    services.vault.enable = true;
+    services.vault.extraSettingsPaths = [ "/run/vault.hcl" ];
+
+    systemd.services.vault = {
+      after = [
+        "postgresql.service"
+      ];
+      # Try for about 10 minutes rather than the default of 5 attempts.
+      serviceConfig.RestartSec = 1;
+      serviceConfig.StartLimitBurst = 600;
+    };
+    # systemd.services.vault.unitConfig.RequiresMountsFor = "/run/keys/";
+
+    services.postgresql.enable = true;
+    services.postgresql.initialScript = pkgs.writeText "init.psql" ''
+      CREATE USER vaultuser WITH ENCRYPTED PASSWORD 'thisisthepass';
+      GRANT CONNECT ON DATABASE postgres TO vaultuser;
+
+      -- https://www.vaultproject.io/docs/configuration/storage/postgresql
+      CREATE TABLE vault_kv_store (
+        parent_path TEXT COLLATE "C" NOT NULL,
+        path        TEXT COLLATE "C",
+        key         TEXT COLLATE "C",
+        value       BYTEA,
+        CONSTRAINT pkey PRIMARY KEY (path, key)
+      );
+      CREATE INDEX parent_path_idx ON vault_kv_store (parent_path);
+
+      GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO vaultuser;
+    '';
+  };
+
+  testScript =
+    ''
+      secretConfig = """
+          storage "postgresql" {
+            connection_url = "postgres://vaultuser:thisisthepass@localhost/postgres?sslmode=disable"
+          }
+          """
+
+      start_all()
+
+      machine.wait_for_unit("multi-user.target")
+      machine.succeed("cat >/root/vault.hcl <<EOF\n%s\nEOF\n" % secretConfig)
+      machine.succeed(
+          "install --owner vault --mode 0400 /root/vault.hcl /run/vault.hcl; rm /root/vault.hcl"
+      )
+      machine.wait_for_unit("vault.service")
+      machine.wait_for_open_port(8200)
+      machine.succeed("vault operator init")
+      machine.succeed("vault status | grep Sealed | grep true")
+    '';
+})
diff --git a/nixos/tests/vault.nix b/nixos/tests/vault.nix
index ffdc3957472..59bccbe2595 100644
--- a/nixos/tests/vault.nix
+++ b/nixos/tests/vault.nix
@@ -8,6 +8,7 @@ import ./make-test-python.nix ({ pkgs, ... }:
     environment.systemPackages = [ pkgs.vault ];
     environment.variables.VAULT_ADDR = "http://127.0.0.1:8200";
     services.vault.enable = true;
+    virtualisation.memorySize = 512;
   };
 
   testScript =