add `beacon_node_payload_builder_enabled` flag (#12)

Signed-off-by: Artur Marud <artur@status.im>

defaults/main.yml

@@ -93,7 +93,8 @@ beacon_node_web3_urls: ['wss://goerli.infura.io/ws/v3/6224f3c792cc443fafb64e70a9
 beacon_node_web3_jwt_secret_path: '{{ beacon_node_service_path }}/jwt.hex'
 
 # Builder for profit-optimized execution payloads.
-#beacon_node_payload_builder: ~
+beacon_node_payload_builder_enabled: false
+#beacon_node_payload_builder_url: ~
 
 # Version of schema for SQLite slashing database.
 beacon_node_slashing_db_kind: 'v2'

templates/beacon-node.service.j2

@@ -28,8 +28,8 @@ ExecStart={{ beacon_node_repo_path }}/build/nimbus_beacon_node \
 {% if beacon_node_web3_jwt_secret is defined %}
     --jwt-secret={{ beacon_node_web3_jwt_secret_path | mandatory }} \
 {% endif %}
-{% if beacon_node_payload_builder is defined and beacon_node_payload_builder | length %}
-    --payload-builder={{ beacon_node_payload_builder }} \
+{% if beacon_node_payload_builder_enabled %}
+    --payload-builder={{ beacon_node_payload_builder_url | mandatory }} \
 {% endif %}
     --log-format={{ beacon_node_log_format }} \
     --log-level={{ beacon_node_log_level }} \