IIS configuration for HTTP to HTTPS redirects behind an AWS Electric Load Balancer; IIS URL Rewrite must be installed.

web.config

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="HTTPS rewrite behind AWS Electric Load Balancer rule" enabled="true" stopProcessing="true">
                    <match url="^(.*)$" ignoreCase="false" />
                    <conditions>
                        <add input="{HTTP_X_FORWARDED_PROTO}" pattern="^http$" ignoreCase="false" />
                    </conditions>
                    <action type="Redirect" url="https://{SERVER_NAME}{URL}" redirectType="Found" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>

See http://www.emind.co/how-to/how-to-force-https-behind-aws-elb