This plugin forces WP Engine sites to use HTTPS when generating srcset image urls. This only applies to production sites, staging sites are unaffected. Non-WP Engine sites are also unaffected. Requires PHP 5.3 or above due to the use of namespaces. WP Engine is running 5.3 or above so this shouldn't be a problem unless you run this plugin somewhere else with less than PHP 5.3

I've seen a number of sites running on WP Engine that were originally setup with a non-https URL (e.g. the Site Address and URL Address are http://example.com/ instead of https), however these sites are now running on https through the magic of WP Engine. Unforunately, the WP Engine magic that makes this possible does not cover the srcset attribute.

The solution to these woes is to update your site URL (or URLs in the case of multisite) to https, but this can be a non-trivial task.

The trivial solution is to force all your srcset values to use https by running this plugin.

• Disable responsive images, which I've done in the past as a temporary solution.
• WP Engine offers HTML Post-Processing, which allows you to use regular expressions to update URLs after the page is rendered but before it is delivered to the browser. This is a great tool. Unfortunately, the rules get messy (and outside my skillset) when dealing with srcset and multisite (feel free to take this line as a challenge and craft some WP Engine compatibile regular expression that makes this plugin unneeded).

Sal Ferrarello
2016 Iron Code Studio
GPL 2.0+