diff --git a/nixos/modules/services/web-apps/mastodon.nix b/nixos/modules/services/web-apps/mastodon.nix
index aea1c9228676..7fc710c6fcec 100644
--- a/nixos/modules/services/web-apps/mastodon.nix
+++ b/nixos/modules/services/web-apps/mastodon.nix
@@ -4,7 +4,8 @@ let
   cfg = config.services.mastodon;
   opt = options.services.mastodon;
 
-  # We only want to create a database if we're actually going to connect to it.
+  # We only want to create a Redis and PostgreSQL databases if we're actually going to connect to it local.
+  redisActuallyCreateLocally = cfg.redis.createLocally && (cfg.redis.host == "127.0.0.1" || cfg.redis.enableUnixSocket);
   databaseActuallyCreateLocally = cfg.database.createLocally && cfg.database.host == "/run/postgresql";
 
   env = {
@@ -117,11 +118,11 @@ let
       threads = toString (if processCfg.threads == null then cfg.sidekiqThreads else processCfg.threads);
     in {
       after = [ "network.target" "mastodon-init-dirs.service" ]
-        ++ lib.optional cfg.redis.createLocally "redis-mastodon.service"
+        ++ lib.optional redisActuallyCreateLocally "redis-mastodon.service"
         ++ lib.optional databaseActuallyCreateLocally "postgresql.service"
         ++ lib.optional cfg.automaticMigrations "mastodon-init-db.service";
       requires = [ "mastodon-init-dirs.service" ]
-        ++ lib.optional cfg.redis.createLocally "redis-mastodon.service"
+        ++ lib.optional redisActuallyCreateLocally "redis-mastodon.service"
         ++ lib.optional databaseActuallyCreateLocally "postgresql.service"
         ++ lib.optional cfg.automaticMigrations "mastodon-init-db.service";
       description = "Mastodon sidekiq${jobClassLabel}";
@@ -149,11 +150,11 @@ let
         name = "mastodon-streaming-${toString i}";
         value = {
           after = [ "network.target" "mastodon-init-dirs.service" ]
-            ++ lib.optional cfg.redis.createLocally "redis-mastodon.service"
+            ++ lib.optional redisActuallyCreateLocally "redis-mastodon.service"
             ++ lib.optional databaseActuallyCreateLocally "postgresql.service"
             ++ lib.optional cfg.automaticMigrations "mastodon-init-db.service";
           requires = [ "mastodon-init-dirs.service" ]
-            ++ lib.optional cfg.redis.createLocally "redis-mastodon.service"
+            ++ lib.optional redisActuallyCreateLocally "redis-mastodon.service"
             ++ lib.optional databaseActuallyCreateLocally "postgresql.service"
             ++ lib.optional cfg.automaticMigrations "mastodon-init-db.service";
           wantedBy = [ "mastodon.target" "mastodon-streaming.target" ];
@@ -410,6 +411,13 @@ in {
           default = 31637;
         };
 
+        passwordFile = lib.mkOption {
+          description = lib.mdDoc "A file containing the password for Redis database.";
+          type = lib.types.nullOr lib.types.path;
+          default = null;
+          example = "/run/keys/mastodon-redis-password";
+        };
+
         enableUnixSocket = lib.mkOption {
           description = lib.mdDoc "Use Unix socket";
           type = lib.types.bool;
@@ -623,6 +631,13 @@ in {
 
   config = lib.mkIf cfg.enable (lib.mkMerge [{
     assertions = [
+      {
+        assertion = redisActuallyCreateLocally -> (!cfg.redis.enableUnixSocket || cfg.redis.passwordFile == null);
+        message = ''
+          <option>services.mastodon.redis.enableUnixSocket</option> needs to be disabled if
+            <option>services.mastodon.redis.passwordFile</option> is used.
+        '';
+      }
       {
         assertion = databaseActuallyCreateLocally -> (cfg.user == cfg.database.user && cfg.database.user == cfg.database.name);
         message = ''
@@ -700,6 +715,8 @@ in {
         OTP_SECRET="$(cat ${cfg.otpSecretFile})"
         VAPID_PRIVATE_KEY="$(cat ${cfg.vapidPrivateKeyFile})"
         VAPID_PUBLIC_KEY="$(cat ${cfg.vapidPublicKeyFile})"
+      '' + lib.optionalString (cfg.redis.passwordFile != null)''
+        REDIS_PASSWORD="$(cat ${cfg.redis.passwordFile})"
       '' + lib.optionalString (cfg.database.passwordFile != null) ''
         DB_PASS="$(cat ${cfg.database.passwordFile})"
       '' + lib.optionalString cfg.smtp.authenticate ''
@@ -762,11 +779,11 @@ in {
 
     systemd.services.mastodon-web = {
       after = [ "network.target" "mastodon-init-dirs.service" ]
-        ++ lib.optional cfg.redis.createLocally "redis-mastodon.service"
+        ++ lib.optional redisActuallyCreateLocally "redis-mastodon.service"
         ++ lib.optional databaseActuallyCreateLocally "postgresql.service"
         ++ lib.optional cfg.automaticMigrations "mastodon-init-db.service";
       requires = [ "mastodon-init-dirs.service" ]
-        ++ lib.optional cfg.redis.createLocally "redis-mastodon.service"
+        ++ lib.optional redisActuallyCreateLocally "redis-mastodon.service"
         ++ lib.optional databaseActuallyCreateLocally "postgresql.service"
         ++ lib.optional cfg.automaticMigrations "mastodon-init-db.service";
       wantedBy = [ "mastodon.target" ];
@@ -847,7 +864,7 @@ in {
       enable = true;
       hostname = lib.mkDefault "${cfg.localDomain}";
     };
-    services.redis.servers.mastodon = lib.mkIf cfg.redis.createLocally (lib.mkMerge [
+    services.redis.servers.mastodon = lib.mkIf redisActuallyCreateLocally (lib.mkMerge [
       {
         enable = true;
       }
diff --git a/nixos/tests/web-apps/mastodon/default.nix b/nixos/tests/web-apps/mastodon/default.nix
index 411ebfcd731b..178590d13b63 100644
--- a/nixos/tests/web-apps/mastodon/default.nix
+++ b/nixos/tests/web-apps/mastodon/default.nix
@@ -5,5 +5,5 @@ let
 in
 {
   standard = handleTestOn supportedSystems ./standard.nix { inherit system; };
-  remote-postgresql = handleTestOn supportedSystems ./remote-postgresql.nix { inherit system; };
+  remote-databases = handleTestOn supportedSystems ./remote-databases.nix { inherit system; };
 }
diff --git a/nixos/tests/web-apps/mastodon/remote-postgresql.nix b/nixos/tests/web-apps/mastodon/remote-databases.nix
similarity index 80%
rename from nixos/tests/web-apps/mastodon/remote-postgresql.nix
rename to nixos/tests/web-apps/mastodon/remote-databases.nix
index 6548883db452..fa6430a99353 100644
--- a/nixos/tests/web-apps/mastodon/remote-postgresql.nix
+++ b/nixos/tests/web-apps/mastodon/remote-databases.nix
@@ -16,7 +16,14 @@ in
   meta.maintainers = with pkgs.lib.maintainers; [ erictapen izorkin ];
 
   nodes = {
-    database = { config, ... }: {
+    databases = { config, ... }: {
+      environment = {
+        etc = {
+          "redis/password-redis-db".text = ''
+            ogjhJL8ynrP7MazjYOF6
+          '';
+        };
+      };
       networking = {
         interfaces.eth1 = {
           ipv4.addresses = [
@@ -24,7 +31,17 @@ in
           ];
         };
         extraHosts = hosts;
-        firewall.allowedTCPPorts = [ config.services.postgresql.port ];
+        firewall.allowedTCPPorts = [
+          config.services.redis.servers.mastodon.port
+          config.services.postgresql.port
+        ];
+      };
+
+      services.redis.servers.mastodon = {
+        enable = true;
+        bind = "0.0.0.0";
+        port = 31637;
+        requirePassFile = "/etc/redis/password-redis-db";
       };
 
       services.postgresql = {
@@ -83,6 +100,9 @@ in
 
       environment = {
         etc = {
+          "mastodon/password-redis-db".text = ''
+            ogjhJL8ynrP7MazjYOF6
+          '';
           "mastodon/password-posgressql-db".text = ''
             SoDTZcISc3f1M1LJsRLT
           '';
@@ -108,6 +128,12 @@ in
         localDomain = "mastodon.local";
         enableUnixSocket = false;
         streamingProcesses = 2;
+        redis = {
+          createLocally = false;
+          host = "192.168.2.102";
+          port = 31637;
+          passwordFile = "/etc/mastodon/password-redis-db";
+        };
         database = {
           createLocally = false;
           host = "192.168.2.102";
@@ -151,12 +177,14 @@ in
     extraInit = ''
       nginx.wait_for_unit("nginx.service")
       nginx.wait_for_open_port(443)
-      database.wait_for_unit("postgresql.service")
-      database.wait_for_open_port(5432)
+      databases.wait_for_unit("redis-mastodon.service")
+      databases.wait_for_unit("postgresql.service")
+      databases.wait_for_open_port(31637)
+      databases.wait_for_open_port(5432)
     '';
     extraShutdown = ''
       nginx.shutdown()
-      database.shutdown()
+      databases.shutdown()
     '';
   };
 })
diff --git a/nixos/tests/web-apps/mastodon/script.nix b/nixos/tests/web-apps/mastodon/script.nix
index afb7c0e0a0eb..9184c63c8941 100644
--- a/nixos/tests/web-apps/mastodon/script.nix
+++ b/nixos/tests/web-apps/mastodon/script.nix
@@ -8,7 +8,6 @@
 
   ${extraInit}
 
-  server.wait_for_unit("redis-mastodon.service")
   server.wait_for_unit("mastodon-sidekiq-all.service")
   server.wait_for_unit("mastodon-streaming.target")
   server.wait_for_unit("mastodon-web.service")
diff --git a/nixos/tests/web-apps/mastodon/standard.nix b/nixos/tests/web-apps/mastodon/standard.nix
index e14cf592332e..ddc764e2168c 100644
--- a/nixos/tests/web-apps/mastodon/standard.nix
+++ b/nixos/tests/web-apps/mastodon/standard.nix
@@ -83,6 +83,7 @@ in
     extraInit = ''
       server.wait_for_unit("nginx.service")
       server.wait_for_open_port(443)
+      server.wait_for_unit("redis-mastodon.service")
       server.wait_for_unit("postgresql.service")
       server.wait_for_open_port(5432)
     '';