Redirecting to an external domain with traefik

German Version

Welcome to another blog post! This time we will look at how to redirect to an external url using traefik without using a container. Docker is completely optional, but I run my traefik with docker, so I will refer to that as well. This should also work with others, but I have not tested or done so yet.

Setting up the file provider

To inject our redirects into traefik we will use the file provider. To do this we need to do two things

Create a file provider directory

Create a new directory provider next to your compose file and mount it into your container.

    volumes:
      - "./provider/:/provider/"

Enabling the file provider in the configuration

Now we need to modify our traefik.yaml and add a file provider.

providers:
  file:
    directory: "/provider/"
    watch: true

This will make traefik watch every file in our provider directory. This allows us to use multiple files to group our providers and keep them more organised. Traefik will also watch for changes to our providers, so as soon as we edit, create or delete a file, those changes will instantly affect traefik's routing.

Warning

Traefik only monitors files in the root directory, so you cannot use subdirectories.

Warning

Do not forget to restart your traefik container.

Creating a redirect

To create a redirect we need two things, a redirectRegex middleware and a router to accept the requests. For this we will create a file redirect.yml (the name can be anything) in our new provider directory.

Note

Alternatively you can create one file for each redirect. A shell script for this can be found below

Setting up the redirectRegex middleware

http:
  middlewares: # (1)!
    chojo-dev-redirect: # (2)!
      redirectRegex: # (3)!
        regex: "(.*)" # (4)!
        replacement: "https://chojo.dev/" # (5)!
        permanent: false # (6)!

1. We create middlewares, so we use the middleware section.
2. Define a new middleware with the name chojo-dev-redirect.
3. Define the type of the middleware as redirectRegex.
4. Define the regex pattern as (.*), which will basically match anything. This is the part of the url we want to replace. So we really want to replace all of the string.
5. Define the new url we want to redirect to.
6. Mark the redirect as temporary. This will prevent the browser from caching, and changes to our redirect will take effect immediately.

If you want to know what each line does, look at the comments.

Setting up the router

Every router needs a service to which it is connected. Of course, we could use Docker to start a service for each of our redirections, or we could start a single service and reuse it. Luckily traefik already has us covered and offers a service for exactly this use case called noop@internal.

Note

The middlewares section is still there, I'm just not showing it.

http:
  routers: # (1)!
    chojo-dev-redirect: # (2)!
      service: noop@internal # (3)!
      entrypoints: "https" # (4)!
      rule: "Host(`my.host.com`)" # (5)!
      middlewares: "chojo-dev-redirect" # (6)!
      tls:
        certresolver: my_cert_resolver # (7)!

1. We are going to create a router, so we will use the routers section.
2. Define a new router called chojo-dev-redirect. I recommend using the same name as the middleware, but it is not required.
3. Add the noop@internal service to our router.
4. Assign the https entrypoint. This may vary depending on your setup.
5. Assign the rule to our host
6. Assign the redirect middleware we defined earlier
7. Assign our cert resolver to the assigned rule

Warning

Make sure you adapt entrypoint, rule and certresolver to your needs!

This will create our service. Anything matching our rule will now be redirected to the domain defined in the redirect middleware.

Using a shell script to create redirects.

I use a bash script to create my redirects.

Script

#!/usr/bin/env sh

read -rp "Enter the name for the router and middleware: " NAME
if [ -z "$NAME" ]; then
    echo "Name cannot be empty. Exiting..."
    exit 1
fi

read -rp "Enter the target URL you want to redirect to: " TARGET
if [ -z "$TARGET" ]; then
    echo "Target URL cannot be empty. Exiting..."
    exit 1
fi

read -rp "Enter the host that should be redirected: " HOST
if [ -z "$HOST" ]; then
    echo "Host cannot be empty. Exiting..."
    exit 1
fi

read -rp "Enter the cert resolver: " CERT
if [ -z "$CERT" ]; then
    echo "Cert resolver cannot be empty. Exiting..."
    exit 1
fi

read -rp "Do you want the redirection to be permanent? [y/N]: " PERMANENT_INPUT
PERMANENT_INPUT=${PERMANENT_INPUT:-n}

PERMANENT=false

if [ "${PERMANENT_INPUT}" = "y" ] || [ "${PERMANENT_INPUT}" = "Y" ]; then
  PERMANENT=true
elif [ "${PERMANENT_INPUT}" != "n" ] && [ "${PERMANENT_INPUT}" != "N" ]; then
  echo "Invalid input for permanent value."
  exit 1
fi

TEXT="http:
  middlewares:
    ${NAME}-redirect:
      redirectRegex:
        regex: \"(.*)\"
        replacement: \"${TARGET}\"
        permanent: ${PERMANENT}
  routers:
    ${NAME}-redirect:
      service: noop@internal
      entrypoints: \"https\"
      rule: \"Host(\`${HOST}\`)\"
      middlewares: \"${NAME}-redirect\"
      tls:
        certresolver: ${CERT}"

echo "$TEXT" > "${NAME}-redirect.yml"
echo "$TEXT"
echo "File ${NAME}-redirect.yml created."

You can get it with

wget https://chojo.dev/assets/files/redirect.sh && chmod +x redirect.sh

Warning

Never run a bash script without looking at them!

The bash script creates a file for each redirect. This makes them easy to find. If you want to change it, just create it again with the same name.

Thank you

Thanks for reading! If you liked this post, or have some questions, feel free to come by my discord and have a chat!

Or write me a mail at mail [at] chojo [dot] dev.

If you want to support me, feel free to sponsor me via GitHub.