use images property on all posts and in the main page so it get's picked up by hugo as open graph tags that will show up in social media posts.

config.yaml

@@ -23,6 +23,8 @@ markup:
 params:
   # Open graph allows easy social sharing. If you don't want it you can set it to false or just delete the variable
   openGraph: true
+  images:
+    - illustrations/flow.svg
   # Used as meta data; describe your site to make Google Bots happy
   description: Homepage for SpiffWorkflow and SpiffArena - open source projects which seek to improve transparency and understanding in organizations through intuitive executable diagrams.  These projects are based on the OMG's BPMN and DMN standards.
   # Preloader ensures images are loaded before displaying to the user. If you don't want it uncomment to set it to false

content/posts/articles/get_started.md

@@ -3,7 +3,8 @@ title: "Getting Started"
 date: 2022-12-27T13:15:00-05:00
 draft: false
 author: Dan Funk
-thumbnail: /images/articles/get_started_thumbnail.png
+images: 
+ - /images/articles/get_started_thumbnail.png
 description: Detailed directions on how to install SpiffArena and create and run your first executable SpiffWorkflow diagram.
 --- 
 In this article (and accompanying video) you will create and run your first executable SpiffWorkflow diagram.  We'll be using a brand new open source application called SpiffArena that wraps the SpiffWorkflow library in an easier to use interface that provides a host of important tools.  Let's get started and you can see for yourself ...

content/posts/articles/visual_workflows.md

@@ -4,7 +4,8 @@ subtitle: "The future of business software is drawn in the code"
 date: 2021-12-01T13:15:00-05:00
 draft: false
 author: Dan Funk
-thumbnail: images/articles/lowcode_thumbnail.png
+images:
+ - /images/articles/lowcode_thumbnail.png
 description: A business level introduction to SpiffWorkflow and why we adopted this open source platform and are building a suite of tools around it.
 ---
 

content/posts/deep_dives/approval.md

@@ -4,7 +4,8 @@ subtitle: "How to create a multi-person approval process"
 date: 2023-01-02T14:09:00-05:00
 draft: false
 author: Alex Herron & Dan Funk
-thumbnail: /images/articles/parallel_approval_thumbnail.png
+images: 
+ - /images/articles/parallel_approval_thumbnail.png
 description: Detailed instructions for building a parallel approval process in BPMN for SpiffWorkflow.
 ---
 

content/posts/deep_dives/data_objects.md

@@ -4,7 +4,8 @@ subtitle: "Or, “A diagram of Love”"
 date: 2022-09-13T10:00:00-05:00
 draft: false
 author: Dan Funk
-thumbnail: /images/articles/data_object_thumbnail.png
+images: 
+ - /images/articles/data_object_thumbnail.png
 description: A thorough explanation of BPMN's Data Objects and how they can be used within SpiffWorkflow. 
 --- 
 

content/posts/deep_dives/messages.md

@@ -4,7 +4,8 @@ subtitle: "Or, “A diagram of Love”"
 date: 2022-09-21T10:00:00-05:00
 draft: false
 author: Dan Funk
-thumbnail: /images/articles/messages_thumbnail.png
+images:
+ - /images/articles/messages_thumbnail.png
 description: A thorough explanation of BPMN's Messages -- a poorly understood, but extremely powerful tool for managing communications with a running BPMN process.
 --- 
 

layouts/_default/list.html

@@ -35,8 +35,8 @@
                     <section class="item">
                         <div class="item-thumbnail">
                             <a href="{{.RelPermalink}}">
-                            {{ with .Params.thumbnail }}
-                            <img src="{{ . | relURL }}" alt="Thumbnail">
+                            {{ with .Params.images }}
+                            <img src="{{ index . 0 }}" alt="Thumbnail">
                             {{ else }}
                             <img src="{{"images/default_thumbnail.png" | relURL}}" alt="Thumbnail">
                             {{ end }}