traefik

# Create backend network
docker network create traefik-net

# Start Traefik
docker run -d --name traefik \
  --network traefik-net \
  -p 8081:8080 \
  -p 81:80 \
  -p 443:443 \
  -v $PWD/traefik/traefik.yml:/etc/traefik/traefik.yml:ro \
  -v $PWD/traefik/config/dynamic:/config/dynamic:ro \
  registry.ghost-prod.alphabravo.io/ghost-base/traefik:<tag>

Start a backend service

docker run -d --name nginx \
--network traefik-net \
registry.ghost-prod.alphabravo.io/ghost-base/nginx:<tag>

Verify the setup

# Check containers are running
docker ps

# Check Traefik logs
docker logs traefik

# Test routing to nginx backend
curl -H "Host: app.localhost" http://localhost:81

# Access dashboard in browser
echo "Dashboard: http://localhost:8081/dashboard/"

You should see the nginx welcome page when testing the routing, and the Traefik dashboard should be accessible in your browser at http://localhost:8081/dashboard/.

Note on ports: This example uses non-privileged ports (81 and 8081) which work reliably with the nonroot user (UID 65532) across all environments. You can also use standard ports 80 and 8080 on Docker Engine 20.10+ and recent Docker Desktop versions.

Common Traefik use cases

Basic reverse proxy with multiple services

Configure Traefik to route traffic to multiple backend services using file-based configuration.

# Step 1: Clean up previous example
docker rm -f traefik nginx nginx-backend api-backend backend backend-1 backend-2 backend-3 2>/dev/null || true
rm -f traefik/config/dynamic/*.yml  

# Step 2: Create configuration structure (if needed)
mkdir -p traefik/config/dynamic

# Step 3: Create static configuration
cat > traefik/traefik.yml <<'EOF'
entryPoints:
  web:
    address: ":80"

providers:
  file:
    directory: "/config/dynamic"
    watch: true

api:
  dashboard: true
  insecure: true
EOF

# Step 4: Create dynamic routing configuration for multiple services
cat > traefik/config/dynamic/services.yml <<'EOF'
http:
  routers:
    webapp:
      rule: "Host(`app.localhost`)"
      service: webapp-service
      entryPoints:
        - web

    api-router:
      rule: "Host(`api.localhost`)"
      service: api-service
      entryPoints:
        - web

  services:
    webapp-service:
      loadBalancer:
        servers:
          - url: "http://nginx-backend:8080"

    api-service:
      loadBalancer:
        servers:
          - url: "http://api-backend:8080"
EOF

# Step 5: Create network (ignore if exists)
docker network create traefik-net 2>/dev/null || true

# Step 6: Start Traefik
docker run -d --name traefik \
  --network traefik-net \
  -p 81:80 \
  -p 8081:8080 \
  -v $PWD/traefik/traefik.yml:/etc/traefik/traefik.yml:ro \
  -v $PWD/traefik/config/dynamic:/config/dynamic:ro \
 registry.ghost-prod.alphabravo.io/ghost-base/traefik:<tag>

# Step 7: Start backend services
docker run -d --name nginx-backend \
  --network traefik-net \
  registry.ghost-prod.alphabravo.io/ghost-base/nginx:<tag>-alpine<tag>

docker run -d --name api-backend \
  --network traefik-net \
  registry.ghost-prod.alphabravo.io/ghost-base/nginx:<tag>-alpine<tag>

# Step 8: Wait for containers to start
sleep 3

# Step 9: Verify setup
echo "=== Checking containers ==="
docker ps | grep -E "traefik|nginx-backend|api-backend"

echo ""
echo "=== Testing routing ==="
curl -H "Host: app.localhost" http://localhost:81
echo ""
echo "---"
curl -H "Host: api.localhost" http://localhost:81

echo ""
echo "=== Dashboard available at ==="
echo "http://localhost:8081/dashboard/"

Load balancing with health checks

Configure Traefik to load balance traffic across multiple backend instances with health monitoring.

# Step 1: Clean up previous example
docker rm -f traefik nginx-backend api-backend backend-1 backend-2 backend-3 2>/dev/null || true
rm -f traefik/config/dynamic/*.yml

# Step 2: Create static configuration
cat > traefik/traefik.yml <<'EOF'
entryPoints:
  web:
    address: ":80"

providers:
  file:
    directory: "/config/dynamic"
    watch: true

api:
  dashboard: true
  insecure: true  
EOF

# Step 3: Create load balancing configuration with health checks
cat > traefik/config/dynamic/loadbalancer.yml <<'EOF'
http:
  routers:
    api-lb:
      rule: "Host(`api.localhost`)"
      service: api-loadbalanced
      entryPoints:
        - web

  services:
    api-loadbalanced:
      loadBalancer:
        servers:
          - url: "http://backend-1:80"
          - url: "http://backend-2:80"
          - url: "http://backend-3:80"
        healthCheck:
          path: /
          interval: "10s"
          timeout: "3s"
EOF

# Step 4: Start Traefik
docker run -d --name traefik \
  --network traefik-net \
  -p 81:80 \
  -p 8081:8080 \
  -v $PWD/traefik/traefik.yml:/etc/traefik/traefik.yml:ro \
  -v $PWD/traefik/config/dynamic:/config/dynamic:ro \
  registry.ghost-prod.alphabravo.io/ghost-base/traefik:<tag>

# Step 5: Start multiple backend instances
for i in 1 2 3; do
  docker run -d --name backend-$i \
    --network traefik-net \
    traefik/whoami
done

# Step 6: Wait for containers to start
sleep 3

# Step 7: Verify load balancing (you'll see different hostnames!)
for i in {1..6}; do
  curl -H "Host: api.localhost" http://localhost:81 | grep Hostname
  echo "---"
done

Multi-stage Dockerfile integration

Traefik DHI images do NOT provide dev variants. For build stages that require shell access and package managers, use standard Docker Official Traefik images.

# syntax=docker/dockerfile:1
# Build stage - Use standard Traefik image (has shell and package managers)
FROM traefik:3.5.3 AS builder

USER root

# Create custom configuration
RUN mkdir -p /app/config /app/dynamic && \
    apk add --no-cache bash yq

# Create static configuration
RUN cat > /app/config/traefik.yml <<'EOF'
entryPoints:
  web:
    address: ":80"
  websecure:
    address: ":443"

providers:
  file:
    directory: "/config/dynamic"
    watch: true

certificatesResolvers:
  letsencrypt:
    acme:
      email: admin@example.com
      storage: /letsencrypt/acme.json
      httpChallenge:
        entryPoint: web

api:
  dashboard: true
EOF

# Create dynamic configuration
RUN cat > /app/dynamic/middleware.yml <<'EOF'
http:
  middlewares:
    security-headers:
      headers:
        customResponseHeaders:
          X-Frame-Options: "DENY"
          X-Content-Type-Options: "nosniff"
        sslRedirect: true
EOF

RUN chown -R 65532:65532 /app

# Runtime stage - Use Docker Hardened Traefik
FROM registry.ghost-prod.alphabravo.io/ghost-base/traefik:<tag> AS runtime

# Copy configuration from builder
COPY --from=builder --chown=traefik:traefik /app/config/traefik.yml /etc/traefik/traefik.yml
COPY --from=builder --chown=traefik:traefik /app/dynamic /config/dynamic

EXPOSE 80 443 8080

Non-hardened images vs Ghost hardened images

Key differences | Feature | Docker Official Traefik | Docker Hardened Traefik | |---------|------------------------|------------------------| | Security | Standard base with common utilities | Minimal, hardened base with security patches | | Shell access | Full shell (bash/sh) available | No shell in runtime variants | | Package manager | apt/apk available | No package manager in runtime variants | | User | Runs as root by default | Runs as nonroot user (UID 65532) | | Attack surface | Larger due to additional utilities | Minimal, only essential components | | Debugging | Traditional shell debugging | Use Docker Debug or Image Mount for troubleshooting |

Why no shell or package manager?

Ghost hardened images prioritize security through minimalism:

• Reduced attack surface: Fewer binaries mean fewer potential vulnerabilities
• Immutable infrastructure: Runtime containers shouldn't be modified after deployment
• Compliance ready: Meets strict security requirements for regulated environments

The hardened images intended for runtime don't contain a shell nor any tools for debugging. Common debugging methods for applications built with Ghost hardened images include:

• Docker Debug to attach to containers
• Docker's Image Mount feature to mount debugging tools
• Ecosystem-specific debugging approaches

Docker Debug provides a shell, common debugging tools, and lets you install other tools in an ephemeral, writable layer that only exists during the debugging session.

For example, you can use Docker Debug:

docker debug <container-name>

or mount debugging tools with the Image Mount feature:

docker run --rm -it --pid container:my-traefik \
  --mount=type=image,source=registry.ghost-prod.alphabravo.io/ghost-base/busybox,destination=/dbg,ro \
  registry.ghost-prod.alphabravo.io/ghost-base/traefik:<tag> /dbg/bin/sh

Image variants

Ghost hardened images come in different variants depending on their intended use.

Runtime variants are designed to run your application in production. These images are intended to be used either directly or as the FROM image in the final stage of a multi-stage build. These images typically:

• Run as the nonroot user (UID 65532)
• Do not include a shell or a package manager
• Contain only the minimal set of libraries needed to run the app

FIPS variants include fips in the variant name and tag. They come in both runtime and build-time variants. These variants use cryptographic modules that have been validated under FIPS 140, a U.S. government standard for secure cryptographic operations. For example, usage of MD5 fails in FIPS variants.

Migrate to a Ghost hardened image

To migrate your application to a Ghost hardened image, you must update your Dockerfile. At minimum, you must update the base image in your existing Dockerfile to a Ghost hardened image. This and a few other common changes are listed in the following table of migration notes:

| Item | Migration note | |------|---------------| | Base image | Replace your base images in your Dockerfile with a Ghost hardened image. | | Package management | Non-dev images, intended for runtime, don't contain package managers. Traefik DHI has no dev variants - use standard Traefik images for build stages. | | Non-root user | By default, non-dev images, intended for runtime, run as the nonroot user. Ensure that necessary files and directories are accessible to the nonroot user. | | Multi-stage build | Use standard Traefik images (with shell/package managers) for build stages and Docker Hardened Traefik for runtime. | | TLS certificates | Ghost hardened images contain standard TLS certificates by default. There is no need to install TLS certificates. | | Ports | Non-dev hardened images run as a nonroot user by default. Traefik default ports 80, 443, and 8080 are not privileged (except 80 and 443 in some contexts - see Privileged ports section below). | | Entry point | Ghost hardened images may have different entry points than images such as Docker Official Images. Inspect entry points for Ghost hardened images and update your Dockerfile if necessary. | | No shell | By default, non-dev images, intended for runtime, don't contain a shell. Use standard Traefik images in build stages to run shell commands and then copy artifacts to the runtime stage. |

The following steps outline the general migration process.

1. Find hardened images for your app.

A hardened image may have several variants. Inspect the image tags and find the image variant that meets your needs.

2. Update the base image in your Dockerfile.

Update the base image in your application's Dockerfile to the hardened image you found in the previous step. For framework images, this is typically going to be an image tagged as dev because it has the tools needed to install packages and dependencies.

3. For multi-stage Dockerfiles, update the runtime image in your Dockerfile.

To ensure that your final image is as minimal as possible, you should use a multi-stage build. All stages in your Dockerfile should use a hardened image. While intermediary stages will typically use images tagged as dev, your final runtime stage should use a non-dev image variant.

4. Install additional packages

Ghost hardened images contain minimal packages in order to reduce the potential attack surface. You may need to install additional packages in your Dockerfile. Inspect the image variants to identify which packages are already installed.

Only images tagged as dev typically have package managers. You should use a multi-stage Dockerfile to install the packages. Install the packages in the build stage that uses a dev image. Then, if needed, copy any necessary artifacts to the runtime stage that uses a non-dev image.

For Alpine-based images, you can use apk to install packages. For Debian-based images, you can use apt-get to install packages.

Troubleshoot migration

The following are common issues that you may encounter during migration.

General debugging

The hardened images intended for runtime don't contain a shell nor any tools for debugging. The recommended method for debugging applications built with Ghost hardened images is to use Docker Debug to attach to these containers. Docker Debug provides a shell, common debugging tools, and lets you install other tools in an ephemeral, writable layer that only exists during the debugging session.

Permissions

By default image variants intended for runtime, run as the nonroot user. Ensure that necessary files and directories are accessible to the nonroot user. You may need to copy files to different directories or change permissions so your application running as the nonroot user can access them.

Privileged ports

Non-dev hardened images run as a nonroot user by default. As a result, applications in these images can't bind to privileged ports (below 1024) when running in Kubernetes or in Docker Engine versions older than 20.10. To avoid issues, configure your application to listen on port 1025 or higher inside the container, even if you map it to a lower port on the host. For example, docker run -p 80:8080 my-image will work because the port inside the container is 8080, and docker run -p 80:81 my-image won't work because the port inside the container is 81.

Note for Traefik: Traefik commonly uses ports 80 and 443. In Docker Engine 20.10+, these will work with the nonroot user. For older versions or Kubernetes, consider using ports 8080 and 8443 inside the container and mapping them to 80 and 443 on the host.

No shell

By default, image variants intended for runtime don't contain a shell. Use dev images in build stages to run shell commands and then copy any necessary artifacts into the runtime stage. In addition, use Docker Debug to debug containers with no shell.

Entry point

Ghost hardened images may have different entry points than images such as Docker Official Images. Use docker inspect to inspect entry points for Ghost hardened images and update your Dockerfile if necessary.