Foreman sandbox devel setup with webpack enabled.

sandbox.conf

<VirtualHost *:443>
  ServerName wraines-sandbox.rdu.redhat.com

  SSLEngine on
  SSLProxyEngine On
  SSLProxyVerify none
  SSLVerifyClient none
  SSLProxyCheckPeerCN off
  SSLProxyCheckPeerName off
  SSLProxyCheckPeerExpire off

  SSLOptions +StdEnvVars +ExportCertData +FakeBasicAuth

  SSLCertificateFile /etc/pki/tls/certs/wraines-sandbox.crt
  SSLCertificateKeyFile /etc/pki/tls/private/wraines-sandbox.key

  RewriteEngine on
  ProxyPreserveHost on

  ProxyPass / https://192.168.121.112/
  ProxyPassReverse / https://192.168.121.112/

  RewriteRule ^/$ https://192.168.121.112/$1 [P,L]

</VirtualHost>

Listen 3808

<VirtualHost *:3808>
  ServerName wraines-sandbox.rdu.redhat.com

  SSLEngine on
  SSLProxyEngine On
  SSLProxyVerify none
  SSLVerifyClient none
  SSLProxyCheckPeerCN off
  SSLProxyCheckPeerName off
  SSLProxyCheckPeerExpire off

  SSLOptions +StdEnvVars +ExportCertData +FakeBasicAuth

  SSLCertificateFile /etc/pki/tls/certs/wraines-sandbox.crt
  SSLCertificateKeyFile /etc/pki/tls/private/wraines-sandbox.key

  RewriteEngine on
  ProxyPreserveHost on

  ProxyPass / https://192.168.121.112:3808/
  ProxyPassReverse / https://192.168.121.112:3808/

  RewriteRule ^/$ https://192.168.121.112:3808/$1 [P,L]

</VirtualHost>

# Production virtual hosts

Listen 5050

<VirtualHost *:5050>
  ServerName wraines-sandbox.rdu.redhat.com                                                                                                                                                                           

  ProxyPreserveHost On
  ProxyPass / https://192.168.121.201/
  ProxyPassReverse / https://192.168.121.201/

  SSLEngine on
  SSLCertificateFile /etc/pki/tls/certs/wraines-sandbox.crt
  SSLCertificateKeyFile /etc/pki/tls/private/wraines-sandbox.key
  ProxyPreserveHost on
  SSLVerifyClient none
  SSLProxyEngine On
  SSLOptions +StdEnvVars +ExportCertData +FakeBasicAuth
  SSLProxyVerify none
  SSLProxyCheckPeerCN off
  SSLProxyCheckPeerName off
  SSLProxyCheckPeerExpire off
</VirtualHost>

Listen 50500

<VirtualHost *:50500>
  ServerName wraines-sandbox.rdu.redhat.com

  ProxyPreserveHost On
  ProxyPass / https://192.168.121.244/
  ProxyPassReverse / https://192.168.121.244/

  SSLEngine on
  SSLCertificateFile /etc/pki/tls/certs/wraines-sandbox.crt
  SSLCertificateKeyFile /etc/pki/tls/private/wraines-sandbox.key
  ProxyPreserveHost on
  SSLVerifyClient none
  SSLProxyEngine On
  SSLOptions +StdEnvVars +ExportCertData +FakeBasicAuth
  SSLProxyVerify none
  SSLProxyCheckPeerCN off
  SSLProxyCheckPeerName off
  SSLProxyCheckPeerExpire off
</VirtualHost>

settings.yaml

##your default puppet server - can be overridden in the host level
#if none specified, plain "puppet" will be used.
#:puppet_server: puppet
:unattended: true
:login: true
:require_ssl: true
:locations_enabled: true
:organizations_enabled: true

# The following values are used for providing default settings during db migrate
:oauth_active: true
:oauth_map_users: true
:oauth_consumer_key: [redacted]
:oauth_consumer_secret: [redacted]

# SSL settings
:ssl_ca_file: /etc/pki/katello/certs/katello-default-ca.crt
:ssl_certificate: /etc/pki/katello/certs/centos7-katello-devel.wraines-sandbox.example.com-foreman-client.crt
:ssl_priv_key: /etc/pki/katello/private/centos7-katello-devel.wraines-sandbox.example.com-foreman-client.key

# webpack dev server settings
:webpack_dev_server: true
:webpack_dev_server_https: true
:assets_debug: true

webpack.config.js.diff

diff --git a/config/webpack.config.js b/config/webpack.config.js
index 2bb234f..a5544f6 100644
--- a/config/webpack.config.js
+++ b/config/webpack.config.js
@@ -239,6 +239,7 @@ module.exports = env => {
     config.devServer = {
       host: devServer.host,
       port: devServer.port,
+      disableHostCheck: true,
       headers: { 'Access-Control-Allow-Origin': '*' },
       hot: true
     };

Note that you need to also add a CSP blocker to chrome in order for this to work. I use this one.