Update OPA example for collection filtering

Author: alukach

examples/opa/docker-compose.yaml

@@ -2,7 +2,9 @@ services:
   proxy:
     environment:
       ITEMS_FILTER_CLS: stac_auth_proxy.filters:Opa
-      ITEMS_FILTER_ARGS: '["http://opa:8181", "stac/cql2"]'
+      ITEMS_FILTER_ARGS: '["http://opa:8181", "stac/items_cql2"]'
+      COLLECTIONS_FILTER_CLS: stac_auth_proxy.filters:Opa
+      COLLECTIONS_FILTER_ARGS: '["http://opa:8181", "stac/collections_cql2"]'
 
   opa:
     image: openpolicyagent/opa:latest

examples/opa/policies/stac/policy.rego

@@ -1,7 +1,13 @@
 package stac
 
-default cql2 := "\"naip:year\" = 2021"
+default items_cql2 := "\"naip:year\" = 2021"
 
-cql2 := "1=1" if {
+items_cql2 := "1=1" if {
+	input.payload.sub != null
+}
+
+default collections_cql2 := "id = 'naip'"
+
+collections_cql2 := "1=1" if {
 	input.payload.sub != null
 }