I understand what you mean now! thanks!
So custom headers don’t work because you need it as part of the POST request body, right?
Right now, the only way to do this is to add the fields you need to the content type for which the webhook is reporting. For example, say you have a blog post content type in Contentful with
body fields. Every time an author publishes a new blog post you want CircleCI to rebuild your statically generated website (for example). In addition to the
body fields, you would need to add the field which CircleCI requires to the blog post content type. This is definitely not a very good way to do this however.
What I would suggest is to use the custom headers as is in the webhook setup, then set up some middleware (using Lambda, now.sh, webtask, etc.) which receives the webhook from Contentful and takes the headers and puts it into the request body which it then passes it along to CircleCI. This is also not great, but better than what I originally suggested.
Don’t worry though! We have a product update in the pipeline for this exact use case which will allow you to define a webhook transformation which will alter the webhook body to align with what your particular webhook receiver (CircleCI in this case) is expecting. We don’t have a firm date for releasing this update, but it should be in the next few months. Keep watch at https://www.contentful.com/developers/changelog/