docs: start working on service adding docs

docs/adding-services.md

@@ -0,0 +1,59 @@
+# Adding services to Bento
+
+There are two types of services in Bento:
+
+* Bento services, which have been developed by the Bento team specifically for the platform, and
+* other services, which support the Bento services or provide additional platform features.
+
+
+## Aspects to consider when adding any service to Bento
+
+* Service environment variables, used for configuring the image and some aspects of the service itself, should be added 
+  to `etc/bento.env`. These variables typically include:
+  * Image
+  * Image version (tag)
+  * Container name template
+  * Service Docker network (**Note:** we typically give each service its own network, and add services to multiple 
+    networks only as needed)
+  * Debugger ports
+* Configuration environment variables TODO
+* Docker container configuration via a Compose file in `lib/<service>/docker-compose.<service>.yaml`
+* *As needed:* a gateway NGINX config in `lib/gateway/<public_services|services>`
+
+* TODO
+
+Non-Bento services **MUST NOT** be put into `etc/bento_services.json`; this file is for Bento services only (see below).
+
+### Required `bentoctl` changes
+
+TODO
+
+
+## Additional considerations when adding new Bento services
+
+### `/service-info` and service record in `bento_services.json`
+
+Bento services **MUST** implement the GA4GH [Service Info](https://www.ga4gh.org/product/service-info/) API.
+They must also be registered in the `etc/bento_services.json` file, which allows them to be loaded into the 
+[Bento Service Registry](https://github.com/bento-platform/bento_service_registry).
+
+Each entry of this file follows the format:
+
+```js
+{
+  // ...
+   "<compose ID>": {
+     "service_kind": "<service kind>",
+     "url_template": "{BENTO_PUBLIC_URL}/api/{service_kind}",
+     "repository": "git@github.com:bento-platform/<...>"
+   },
+  // ...
+}
+```
+
+In this format:
+* `<compose ID>` is the key of the service in its `docker-compose.<...>.yaml` file
+* `<service kind>` is a special Bento-unique identifier for the service, allowing front ends to look up services.
+* The `url_template` key is a template for the base URL used to access the service's API.
+* The `repository` key is an SSH Git repository URL for the service code, so it can be cloned into the `repos` folder
+  for development.