diff --git a/docker/Gemfile b/docker/Gemfile
index 16d6731..a3c6928 100644
--- a/docker/Gemfile
+++ b/docker/Gemfile
@@ -3,7 +3,7 @@
 
 source "https://rubygems.org"
 
-gem "fluentd", "1.14.2"
+gem "fluentd", "1.15.3"
 gem "oj", "3.5.1"
 gem "fluent-plugin-multi-format-parser", "~> 1.0.0"
 gem "fluent-plugin-concat", "~> 2.3.0"
diff --git a/docker/Gemfile.lock b/docker/Gemfile.lock
index 1b93b60..da591c3 100644
--- a/docker/Gemfile.lock
+++ b/docker/Gemfile.lock
@@ -35,12 +35,12 @@ GEM
     fluent-plugin-systemd (1.0.2)
       fluentd (>= 0.14.11, < 2)
       systemd-journal (~> 1.3.2)
-    fluentd (1.14.2)
+    fluentd (1.15.3)
       bundler
       cool.io (>= 1.4.5, < 2.0.0)
-      http_parser.rb (>= 0.5.1, < 0.8.0)
+      http_parser.rb (>= 0.5.1, < 0.9.0)
       msgpack (>= 1.3.1, < 2.0.0)
-      serverengine (>= 2.2.2, < 3.0.0)
+      serverengine (>= 2.3.0, < 3.0.0)
       sigdump (~> 0.2.2)
       strptime (>= 0.2.4, < 1.0.0)
       tzinfo (>= 1.0, < 3.0)
@@ -68,7 +68,7 @@ GEM
       mime-types-data (~> 3.2015)
     mime-types-data (3.2019.0331)
     minitest (5.14.1)
-    msgpack (1.4.2)
+    msgpack (1.7.2)
     netrc (0.11.0)
     oj (3.5.1)
     prometheus-client (0.9.0)
@@ -80,22 +80,22 @@ GEM
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 4.0)
       netrc (~> 0.8)
-    serverengine (2.2.4)
+    serverengine (2.3.2)
       sigdump (~> 0.2.2)
-    sigdump (0.2.4)
+    sigdump (0.2.5)
     strptime (0.2.5)
     systemd-journal (1.3.3)
       ffi (~> 1.9)
     thread_safe (0.3.6)
-    tzinfo (1.2.9)
+    tzinfo (1.2.11)
       thread_safe (~> 0.1)
-    tzinfo-data (1.2021.5)
+    tzinfo-data (1.2023.3)
       tzinfo (>= 1.0.0)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.6)
     webrick (1.7.0)
-    yajl-ruby (1.4.2)
+    yajl-ruby (1.4.3)
     zeitwerk (2.3.0)
 
 PLATFORMS
@@ -110,7 +110,7 @@ DEPENDENCIES
   fluent-plugin-prometheus (~> 1.3.0)
   fluent-plugin-rewrite-tag-filter (~> 2.1.0)
   fluent-plugin-systemd (~> 1.0.1)
-  fluentd (= 1.14.2)
+  fluentd (= 1.15.3)
   oj (= 3.5.1)
 
 BUNDLED WITH