Auto-authenticating to iframe-embedded Kibana dashboard

You can pass the Authorization header as Joe suggests using an nginx proxy.

Here is the relevant section of my nginx.conf:

 server {
     listen       4443 ssl; # the default was port 443
     server_name  tim-virtual-machine.local;

     ssl_certificate      /home/tim/domain.crt;
     ssl_certificate_key  /home/tim/domain.key;

     ssl_session_cache    shared:SSL:1m;
     ssl_session_timeout  5m;

     ssl_ciphers  HIGH:!aNULL:!MD5;
     ssl_prefer_server_ciphers  on;

     location / {
         proxy_set_header  Host $host;
         proxy_set_header  X-Real-IP $remote_addr;
         proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
         proxy_set_header  Authorization "Basic cGFudHM6b25maXJl"; # base64-encoded username:password to pass in header
         proxy_pass  https://tim-virtual-machine.local:5601; # actual kibana URL

I got this mostly from following this tutorial:

I generated the Base64 string out of the username:password combination with this unix one-liner:

echo -n username:password | base64