frohoff / htransformation

A Traefik plugin to change on the fly header's value of a request

Header transformation plugin for traefik

This plugin allows changing on the fly, the header value of a request.

Dev traefik.yml configuration file for traefik

pilot:
  token: [REDACTED]

experimental:
  devPlugin:
    goPath: /home/tm/go
    moduleName: github.com/tommoulard/htransformation

entryPoints:
  http:
    address: ":8000"
    forwardedHeaders:
      insecure: true

api:
  dashboard: true
  insecure: true

providers:
  file:
    filename: rules-htransformation.yaml

How to dev

$ docker run -d --network host containous/whoami -port 5000
# traefik --config-file traefik.yml

How to use

To choose a Rule you have to fill the Type field with one of the following:

• 'Del' : to Delete a header
• 'Join' : to Join values on a header
• 'Rename' : to rename a header
• 'RewriteValueRule': to rewrite header values
• 'Set' : to Set a header

Each Rule can be named with the Name field

Rename

A Rule Rename needs two arguments.

• Header, the regex of the header you want to replace
• Value, the new header

# Example Rename
- Rule:
      Name: 'Header rename'
      Header: 'Cache-Control'
      Value: 'NewHeader'
      Type: 'Rename'

# Old header:
Cache-Control: gzip, deflate

# New header:
NewHeader: gzip, deflate

- Rule:
      Name: 'Header Renaming'
      Header: 'X-Traefik-*'
      Value: 'X-Traefik-merged'
      Type: 'Rename'

# Old header:
X-Traefik-uuid: 0
X-Traefik-date: mer. 21 oct. 2020 11:57:39 CEST
# New header:
X-Traefik-merged: 0 # A value from old headers

Set

A Set rule will either create or replace the header and value (if it already exists)

A rule Set need 2 arguments

• Header, the header you want to create
• Value, the value of the new header

# Example Join
- Rule:
      Name: 'Set Cache-Control'
      Header: 'Cache-Control'
      Value: 'Foo'
      Type: 'Join'

# New header:
Cache-Control: Foo

Delete

A rule Delete need one arguments

• Header, the header you want to delete

# Example Del
- Rule:
      Name: 'Delete Cache-Control'
      Header: 'Cache-Control'
      Type: 'Del'

Join

A Join rule will concatenate the values of the existing header with the new one. If the header doesn't exist, it'll do nothing

It needs 3 arguments

• Header, the header you want to join
• Values, a list of values to add to the existing header
• Sep, the separator you want to use

# Example Join
- Rule:
      Name: 'Header join'
      Header: 'Cache-Control'
      Sep: ','
      Values:
        - 'Foo'
        - 'Bar'
      Type: 'Join'

# Old header:
Cache-Control: gzip, deflate

# Joined header:
Cache-Control: gzip, deflate,Foo,Bar

You can reuse other header values in Value or one of the Values by setting an additional argument HeaderPrefix. Example:

# Example Usage
- Rule:
  Name: 'Header set'
  Header: 'X-Forwarded-For'
  HeaderPrefix: "^"
  Values:
      - 'Foo'
      - '^CF-Connecting-IP'
  Type: 'Join'

# Old header:
X-Forwarded-For: 1.1.1.1
CF-Connecting-IP: 2.2.2.2
# New headers:
CF-Connecting-IP: 2.2.2.2
X-Forwarded-For: Foo, 1.1.1.1

RewriteValue Rule

A RewriteValue Rule will replace the values of the headers identified by a matching regex with the provided value.

It needs 2 arguments

• Header, the header or regex identifying the headers you want to change
• Value, the new value of the headers

# Example RewriteValueRule
- Rule:
      Name: 'Header rewriteValue'
      Header: 'Foo'
      Value: 'X-(.*)'
      ValueReplace: 'Y-$1'
      Type: 'RewriteValueRule'

# Old header:
Foo: X-Test

# Modified header:
Foo: Y-Test

Careful

The rules will be evaluated in the order of definition

#Example
- Rule:
  Name: 'Header addition'
  Header: 'X-Custom-2'
  Value: 'True'
  Type: 'Set'
- Rule:
  Name: 'Header deletion'
  Header: 'X-Custom-2'
  Type: 'Del'
- Rule:
  Name: 'Header join'
  Header: 'X-Custom-2'
  Value: 'False'
  Type: 'Set'

Will set the header X-Custom-2 to 'True', then delete it and set it again but with False

Authors

Tom Moulard	Clément David	Martin Huvelle	Alexandre Bossut-Lasry