This code is based in https://feryn.eu/blog/validating-json-web-tokens-in-varnish/

This code provides asymectric jwt validation RS256 instead symmetric HS256

Features:

• JWT Validation Signature
• JWT Validation expiration
• HIT/MISS Header
• Use Authorization Bearer header
• Support multiple keys

Todo

• Allow multiple jwt validation algorithms
• Improve test

Varnish

This image use this modules:

https://code.uplex.de/uplex-varnish/libvmod-crypto (RSA algorytm)

Generate ssh keys

ssh-keygen -t rsa -b 4096 -m PEM -f private.key
# Don't add passphrase
openssl rsa -in private.key -pubout -outform PEM -out public.pub

Usage with docker-compose

Modify docker-compose.yml file

version: '3.7'
services:
  varnish:
    image: opositatest/varnish:latest
    links:
        - nginx:nginx
    ports:
        - 80:80
    environment:
        PUBLIC_KEY: |-
            -----BEGIN PUBLIC KEY-----
            ...ADD YOUR PUBLIC KEY...
            -----END PUBLIC KEY-----

Update default.vcl and add your custom host

backend default {
  .host = "nginx";
}

Notes

This code requires Authorization bearer:

curl -v -H "Authorization: Bearer AWESOME_TOKEN" -X GET "http://localhost:80/api/v1/some_resource" -H  "accept: application/json"

Test

docker-compose -f docker-compose.test.yml up --abort-on-container-exit

The test files are in folder varnish/test/:

• autorization.vtc

  This test verifies that Varnish is capable of working with JWT. Different content in the token is sent in each test and it is checked if the answer is the expected one.

• single_request.vtc

  This test makes a request emulating a client to check if the backend responds.

If you want test that the Varnish service it is who listen to the request and respond to the request you have verify the response headers and looking for X-Cache:

• X-Cache is HIT: This request was attended by the Varnish server and this object existing on cache.
• X-Cache is MISS: This request was attend by Varnish but is not in cache and Varnish asked the backend for it request.
• X-Cache is not set: This request not was attend by Varnish server.

Example with a curl client:

# Request
curl -I localhost:80

# Response
HTTP/1.1 200 OK
Server: nginx/1.17.9
Date: Thu, 26 Mar 2020 14:27:45 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 03 Mar 2020 14:32:47 GMT
ETag: "5e5e6a8f-264"
X-Varnish: 7 3
Age: 8
Via: 1.1 varnish (Varnish/6.4)
X-Cache: HIT
Accept-Ranges: bytes
Connection: keep-alive