diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..eee3bbb
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,15 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
+
+version: 2
+updates:
+  - package-ecosystem: "pip"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+  - package-ecosystem: "docker"
+    directory: "/"
+    schedule:
+      interval: "monthly"
diff --git a/Dockerfile b/Dockerfile
index 617ac21..5417045 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,13 +1,17 @@
-FROM python:3.9-slim-buster
+FROM python:3.12-slim
 
 WORKDIR /app
 
 RUN apt-get update && apt-get install -y shellcheck \
   && rm -rf /var/lib/apt/lists/*
 
+# prevent 9Mb of cached bytecode files (.pyc)
+ENV PYTHONDONTWRITEBYTECODE=1
+
 COPY requirements.txt requirements.txt
-RUN pip3 install -r requirements.txt
+RUN pip3 install --no-compile --no-cache-dir -r requirements.txt
 
-COPY . .
+COPY yaml_shellcheck.py .
 
+USER 1000
 ENTRYPOINT [ "python3", "yaml_shellcheck.py"]