A simple webserver that only redirects traffic based on a YAML configuration file.

A sample configuration file is available in config.yaml. Each value can also be overridden with an environment variable.

---
bind_address: 0.0.0.0:8080
redirects:
  - rules.yaml

The bind address is the address and port that the HTTP server should listen to. The value can also be set by setting the BIND_ADDRESS environment variable.

The redirects array is evaluated in the order that files appear in the list. Files can be local or remote (http and https only for now). The environment variable REDIRECT_SOURCE can also be used, with multiple values separated by commas.

Each redirect rule has a name, a match pattern, and one or more targets.

To redirect blahblahblah.com (with an optional leading www) to somethingdifferent.com using a 301 redirect you would use

- name: Blah Test
  pattern: ^(www\.)?blahblahblah.com\/
  targets:
  - target: https://somethingdifferent.com/
    code: 301

You can get more complex and redirect based on the source IP address (as reported in the X-Forwareded-For header) too:

- name: TV
  pattern: ^tv\.university\.edu/
  targets:
  - target: https://contour.university.edu
    code: 302
    when:
      source:
        - 10.0.0.0/8
        - 192.168.1.0/24
  - target: https://google.com
    code: 302

The above example essentially says redirect tv.university.edu to contour.university.edu when inside one of the two source IP ranges, otherwise redirect to google.com. Whenever multiple targets are used you should use 302 redirects to avoid browsers caching the redirects.

Because everything is stored as regular expressions, substitutions are also possible:

- name: All to SSL
  pattern: ^(www\.)?(?P<name>[a-zA-Z0-9\-]+).com\/
  targets:
  - target: https://${name}.university.edu/
    code: 301

Regular expressions are evaluated in the order they appear in the configuration file. You should consider having some sort of catch all resource at the bottom to prevent dead end 404s.

Redirect rules can be reloaded without restarting the application by sending an HTTP GET request to /reload.

Everything should work well under Docker without having to modify the base image (using remote redirect rules with environment variables). An image is available on the hub at pcfens/redirector.