First image as cover image in Ghost

gistfile1.diff

diff --git a/core/server/models/post.js b/core/server/models/post.js
index b471f51..5e3c680 100644
--- a/core/server/models/post.js
+++ b/core/server/models/post.js
@@ -44,13 +44,19 @@ Post = ghostBookshelf.Model.extend({
 
     saving: function (newPage, attr, options) {
         /*jslint unparam:true*/
-        var self = this;
+        var self = this,
+            imageMatch;
 
         // Remove any properties which don't belong on the post model
         this.attributes = this.pick(this.permittedAttributes);
 
         this.set('html', converter.makeHtml(this.get('markdown')));
 
+        imageMatch = this.get('markdown').match(/!\[[^\]]+\]\(([^\)]+)\)/);
+        if (imageMatch) {
+            this.set('image', imageMatch[1]);
+        }
+
         this.set('title', this.sanitize('title').trim());
 
         if (this.hasChanged('status') && this.get('status') === 'published') {

I made it for social sharing:

default.hbs:

{{#post}}
<meta property="og:title" content="{{title}}" />
{{#if image}}<meta property="og:image" content="{{@blog.url}}{{image}}" />{{/if}}
<meta property="og:description" content="{{excerpt characters=220}}..." />
{{/post}}