Failure to install x-pack behind proxy

[dmarkhas]

Kibana version: 6.2.2

Elasticsearch version: 6.2.2

Server OS version: Ubuntu 14.04

Browser version:

Browser OS version:

Original install method (e.g. download page, yum, from source, etc.): tarball

Description of the problem including expected versus actual behavior:

When attempting to install x-pack behind a corporate proxy, the http downloader writes the following to the proxy socket:

write(13, "GET http://artifacts.elastic.co:443/downloads/kibana-plugins/x-pack/x-pack-6.2.2.zip HTTP/1.1\r\nHost: artifacts.elastic.co:443\r\nConnection: close\r\n\r\n", 148) = 148

This fails since Elastic's web server returns 503 for such a request.

It does so regardless of whether I run "kibana-plugin install x-pack" or "kibana-plugin install https://artifacts.elastic.co/downloads/kibana-plugins/x-pack/x-pack-6.2.2.zip".
I am guessing this is because you are using the http-proxy-agent, not the https-proxy-agent.

Currently the only workaround is to download the x-pack archive with wget and install it in an offline mode.

Steps to reproduce:

1. Configure a proxy
2. strace the "kibana-plugin install x-pack" command

[tylersmalley]

This has been resolved in #15588 and will be fixed in 6.3