Don't set auth if no user/pass

[meringu]

I'm using cookie based auth to connect to a prometheus endpoint. Not setting a auth means the request gets sent with a Authorization: Basic Og== header. This results in a 401 from my Prometheus endpoint.

This is because axios adds the auth header based on the presense of the auth object, not if it has username or password in it. https://github.com/axios/axios/blob/c7329fefc890050edd51e40e469a154d0117fc55/lib/adapters/http.js#L32.

This PR adds a similar check as what is in place for the proxy config.

Cheers

[samber]

Looks good.
I'm going to publish a new release.

[haghsheno]

@samber I'm using authorization header but yet it shows me authorization: TOKEN ,Basic Og== in request header even if i don't use auth option or set auth: null.

prometheus: {
   endpoint: url,
   auth: null,
   headers: {
      authorization: token,
    },
}

If i set auth: {username: null, password: null}, the decoded result is [object Object]:[object Object].

I expect this in request header:
authorization: TOKEN

[samber]

Hi @haghsheno and thanks for the bug report.

I cannot reproduce this error.

What version of the library are you using?

[samber]

Oh! I see.
Are you using chartjs-plugin-datasource-prometheus?

This plugin is using an old version of prometheus-query-js.
An update is pending. I gonna merge it today.

You can upgrade to chartjs-plugin-datasource-prometheus@1.0.0.