ob-d2 enables Org-Babel support for evaluating D2 code. It was created based on the usage of ob-ditaa. The D2 code is compiled via the d2 command.

#+BEGIN_SRC d2 :file hello.png
x -> y: hello world
#+END_SRC

In addition to the normal header arguments for Babel, ob-d2 uses the :flags header to pass additional flags to the d2 command. :file is required since the output of D2 is an image.

All examples are courtesy of Terrastruct, Inc. who published them in their D2 documentation.

#+BEGIN_SRC d2 :file flags.png :flags -t 101 -s
High Mem Instance -> EC2 <- High CPU Instance: Hosted By
#+END_SRC

#+BEGIN_SRC d2 :file complex.png
clouds: {
  aws: {
    load_balancer -> api
    api -> db
  }
  gcloud: {
    auth -> db
  }
  gcloud -> aws
}
#+END_SRC

ob-d2 is available from Melpa. You can install it directly via package-install if you have Melpa in your package archives. After installation, you can (require 'ob-d2) and enable D2 as a supported language in org-mode by adding it to org-babel-load-languages. For example, something like:

(org-babel-do-load-languages
   'org-babel-load-languages
   '((shell . t)
     (python . t)
     (d2 . t)))

If you use use-package, you can install ob-d2 and ensure org is configured to use it after loading:

(use-package ob-d2
  :ensure t)
(use-package org
  :after ob-d2
  :config
  (org-babel-do-load-languages
   'org-babel-load-languages
   '((d2 . t))))

Download ob-d2.el from this repository to your loadpath and include (require 'ob-d2) in your init.el file.