feat(53): document rest api convention to use uuid instead of ID

docs/technical/rest-api.md

@@ -0,0 +1,37 @@
+---
+layout: default
+title: REST API
+nav_order: 5
+parent: REST API
+permalink: /docs/technical/rest-api
+---
+
+# REST API
+
+## Development conventions
+
+### Use UUID for resource identifiers
+
+Identifiers of resources that are exposed through the REST API must be the UUID and not the internal ID (integer). 
+
+Example resource response:
+
+```diff
+{
+-    "id": 2032,
++    "uuid":  "9a70ad0a-7717-4750-8cb7-c95b62133382",
+    "title": "Skilltree example"
+}
+```
+
+Example API endpoint:
+
+```diff
+- GET /users/2032/settings,
++ GET /users/9a70ad0a-7717-4750-8cb7-c95b62133382/settings,
+```
+
+Concerns regarding using the ID:
+* The incremental nature of IDs gives insights about the amount of resources that exists. Although this information is not confidential for the public, it's preferred to not expose undesired details.
+* Malicious hackers can guess the resource identifiers and therefore attempt to access resources in endpoints that are not protected well enough. UUIDs are not incremental and have a probability of 2^12 which decreases the that chance people guess a UUID. 
+* UUIDs can be shared across environments, allowing us to create consistent database setups when testing for example.