Merge pull request #22882 from aevesdocker/ENGDOCS-2753

Compose: Spec attribute

Author: aevesdocker

content/reference/compose-file/services.md

@@ -2019,6 +2019,12 @@ ulimits:
     hard: 40000
 ```
 
+### `use_api_socket`
+
+When `use_api_socket` is set, the container is able to interact with the underlying container engine through the API socket.
+Your credentials are mounted inside the container so the container acts as a pure delegate for your commands relating to the container engine.
+Typically, commands ran by container can `pull` and `push` to your registry.
+
 ### `user`
 
 `user` overrides the user used to run the container process. The default is set by the image, for example Dockerfile `USER`. If it's not set, then `root`.