diff --git a/.idea/.idea.ab-nginx.dir/.idea/markdown.xml b/.idea/.idea.ab-nginx.dir/.idea/markdown.xml
new file mode 100644
index 0000000..1e34094
--- /dev/null
+++ b/.idea/.idea.ab-nginx.dir/.idea/markdown.xml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="MarkdownSettings">
+    <enabledExtensions>
+      <entry key="MermaidLanguageExtension" value="false" />
+      <entry key="PlantUMLLanguageExtension" value="false" />
+    </enabledExtensions>
+  </component>
+</project>
\ No newline at end of file
diff --git a/build/Dockerfile b/build/Dockerfile
index 75e725a..78dabbb 100644
--- a/build/Dockerfile
+++ b/build/Dockerfile
@@ -2,7 +2,7 @@
 # build AB-NGINX container (based on NGINX mainline)
 #
 
-ARG NGINX_VERSION=1.21.3
+ARG NGINX_VERSION=1.21.6
 FROM nginx:${NGINX_VERSION}-alpine
 ARG NGINX_VERSION