Adding an explanation how to use htpasswd for k8s secret

[jamct]

What does this PR do?

The tip to use htpasswd was not very clear. You have to encode the result to base64. Adding an example command.

Motivation

Make it easier to use basic auth and generate a base64 encoded string.

More

• Added/updated documentation

[ldez]

Hello,

You don't need to encode the result to base64.

I think you are using a docker-compose file, so you need to escape $ as explained here

Note: all dollar signs in the hash need to be doubled for escaping.
To create user:password pair, it's possible to use this command:
echo $(htpasswd -nb user password) | sed -e s/\$/\$\$/g

You can try it with this simple example:

version: "3.7"

services:

  traefik:
    image: traefik:v2.1.2
    command:
      - --entrypoints.web.address=:80
      - --entrypoints.websecure.address=:443
      - --api
      - --providers.docker.exposedbydefault=false
    ports:
      - 80:80
      - 443:443
    labels:
      traefik.enable: true

      traefik.http.routers.traefik.rule: Host(`traefik.localhost`)
      traefik.http.routers.traefik.service: api@internal
      traefik.http.routers.traefik.entrypoints: web

      # echo $(htpasswd -bnBC 10 admin secret) | sed -e s/\\$/\\$\\$/g
      # curl -u admin:secret http://whoami.localhost
      traefik.http.middlewares.auth.basicauth.users: admin:$$2y$$10$$zdGj/1e2U9K1S1kSyI3dqu.XLOkMwvU7RFuR.54.Wwy36iSrB13te

      # htpasswd -bnBC 10 admin admin | openssl base64
      # curl -u admin:admin http://whoami.localhost
      # Doesn't work: level=error msg="error parsing BasicUser: YWRtaW46JDJ5JDEwJEZHYVN0YnR2Q0JjZWswdGczUWdMYU8yWWViMHNLSlpZT3o4STgub2w1OFNQTmNQRjd5WXpPCgo="
      # traefik.http.middlewares.auth.basicauth.users: YWRtaW46JDJ5JDEwJEZHYVN0YnR2Q0JjZWswdGczUWdMYU8yWWViMHNLSlpZT3o4STgub2w1OFNQTmNQRjd5WXpPCgo=

    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro

  whoami:
    image: containous/whoami:v1.4.0
    labels:
      traefik.enable: true

      traefik.http.routers.whoami.rule: Host(`whoami.localhost`)
      traefik.http.routers.whoami.entrypoints: web
      traefik.http.routers.whoami.middlewares: auth

[jamct]

@ldez: I tried to deploy on Kubernetes and got an error saying "invalid base64..."
It worked when I encoded it to base64.

[ldez]

So the base64 is not required for all providers: only for K8s secret.

The base64 encoding is a requirement of Secret, as you can see in the IngressRoute example.

So, you can add a comment in the IngressRoute example to explain that (like in the Docker example), but it cannot be a global tip.

Could you edit your PR, thank you.

[jamct]

moving the explanation to the right place.

[ldez]

Thanks 👍

[jamct]

Thanks @ldez for clarification and quick approval.

[juliens]

LGTM