diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
index 05250c14..b842b02d 100644
--- a/.devcontainer/Dockerfile
+++ b/.devcontainer/Dockerfile
@@ -1,8 +1,11 @@
+FROM mcr.microsoft.com/dotnet/aspnet:6.0-bookworm-slim as dotnet-lts-runtime
+FROM docker.io/library/mono as mono
+
 # https://hub.docker.com/_/microsoft-dotnet-sdk/
 FROM mcr.microsoft.com/dotnet/sdk:8.0
 
 # install ASP.NET Core 6.0 Runtime
-COPY --from=mcr.microsoft.com/dotnet/aspnet:6.0-bookworm-slim /usr/share/dotnet /usr/share/dotnet
+COPY --from=dotnet-lts-runtime /usr/share/dotnet /usr/share/dotnet
 
 # install msbuild for Mono
 # https://hub.docker.com/_/mono/
diff --git a/.devcontainer/keycloak/Dockerfile b/.devcontainer/keycloak/Dockerfile
index b446ae00..19c01acc 100644
--- a/.devcontainer/keycloak/Dockerfile
+++ b/.devcontainer/keycloak/Dockerfile
@@ -4,7 +4,7 @@ ARG KEYCLOAK_VERSION=25.0.4
 FROM alpine as downloader
 ARG KEYCLOAK_VERSION
 RUN set -eux; \
-    apk add curl; \
+    apk add --no-cache curl; \
     # https://github.com/jacekkow/keycloak-protocol-cas
     curl -Lo /tmp/keycloak-protocol-cas.jar https://github.com/jacekkow/keycloak-protocol-cas/releases/download/${KEYCLOAK_VERSION}/keycloak-protocol-cas-${KEYCLOAK_VERSION}.jar;
 
diff --git a/.devcontainer/setup.sh b/.devcontainer/setup.sh
index d0ca4539..de6d76f0 100755
--- a/.devcontainer/setup.sh
+++ b/.devcontainer/setup.sh
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 
 # https://learn.microsoft.com/aspnet/core/security/docker-compose-https#macos-or-linux
-if [ -f "/https/aspnetapp.pem" ] && [ -f "/https/aspnetapp.key" ]; then
+if [[ -f "/https/aspnetapp.pem" ]] && [[ -f "/https/aspnetapp.key" ]]; then
     cat >> /home/vscode/.bashrc <<EOF
 export ASPNETCORE_Kestrel__Certificates__Default__Path="/https/aspnetapp.pem"
 export ASPNETCORE_Kestrel__Certificates__Default__KeyPath="/https/aspnetapp.key"
diff --git a/.github/ISSUE_TEMPLATE/bug_report.md b/.github/ISSUE_TEMPLATE/bug_report.md
index 891c6177..9a3c65c8 100644
--- a/.github/ISSUE_TEMPLATE/bug_report.md
+++ b/.github/ISSUE_TEMPLATE/bug_report.md
@@ -12,6 +12,7 @@ A clear and concise description of what the bug is.
 
 **To Reproduce**
 Steps to reproduce the behavior:
+
 1. Go to '...'
 2. Click on '....'
 3. Scroll down to '....'
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
new file mode 100644
index 00000000..2c103deb
--- /dev/null
+++ b/.github/workflows/lint.yml
@@ -0,0 +1,37 @@
+name: Lint
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - '**/*.md'
+      - '**/*.sh'
+      - '**/Dockerfile'
+      - '.github/workflows/*.yml'
+  pull_request:
+    branches:
+      - main
+    paths:
+      - '**/*.md'
+      - '**/*.sh'
+      - '**/Dockerfile'
+      - '.github/workflows/*.yml'
+
+jobs:
+  build:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Lint Markdown
+        uses: DavidAnson/markdownlint-cli2-action@v16
+        with:
+          globs: '**/*.md'
+      - name: Lint Dockerfile
+        uses: reviewdog/action-hadolint@v1
+      - name: Lint shell script
+        uses: reviewdog/action-shellcheck@v1
+      - name: Lint GitHub Actions workflow
+        uses: reviewdog/action-actionlint@v1
\ No newline at end of file
diff --git a/.hadolint.yaml b/.hadolint.yaml
new file mode 100644
index 00000000..fa20aa5c
--- /dev/null
+++ b/.hadolint.yaml
@@ -0,0 +1,6 @@
+---
+ignored:
+  - DL3006
+  - DL3008
+  - DL3018
+  - DL4006
diff --git a/.markdownlint-cli2.jsonc b/.markdownlint-cli2.jsonc
new file mode 100644
index 00000000..d24c3acb
--- /dev/null
+++ b/.markdownlint-cli2.jsonc
@@ -0,0 +1,6 @@
+{
+  "$schema": "https://raw.githubusercontent.com/DavidAnson/markdownlint-cli2/main/schema/markdownlint-cli2-config-schema.json",
+  "config": {
+    "line-length": false
+  }
+}
diff --git a/README.md b/README.md
index 9a2ca480..146b42ba 100644
--- a/README.md
+++ b/README.md
@@ -1,11 +1,13 @@
 # GSS.Authentication.CAS
 
-[![Build Status][build-badge]][build] [![Code Coverage][codecov-badge]][codecov]
+[![Build Status][build-badge]][build] [![Code Coverage][codecov-badge]][codecov] [![Lint][lint-badge]][lint]
 
 [build]: https://github.com/akunzai/GSS.Authentication.CAS/actions/workflows/build.yml
 [build-badge]: https://github.com/akunzai/GSS.Authentication.CAS/actions/workflows/build.yml/badge.svg
 [codecov]: https://codecov.io/gh/akunzai/GSS.Authentication.CAS
 [codecov-badge]: https://codecov.io/gh/akunzai/GSS.Authentication.CAS/branch/main/graph/badge.svg?token=JGG7Y07SR0
+[lint]: https://github.com/akunzai/GSS.Authentication.CAS/actions/workflows/lint.yml
+[lint-badge]: https://github.com/akunzai/GSS.Authentication.CAS/actions/workflows/lint.yml/badge.svg
 
 CAS Authentication Middleware for OWIN & ASP.NET Core