Merge pull request #2982 from edx/bderusha/libffi-dev-discovery

Add libffi-dev to discovery

playbooks/roles/discovery/defaults/main.yml

@@ -9,7 +9,7 @@
 #
 ##
 # Defaults for role discovery
-# 
+#
 DISCOVERY_GIT_IDENTITY: !!null
 
 # depends upon Newrelic being enabled via COMMON_ENABLE_NEWRELIC
@@ -167,5 +167,6 @@ discovery_log_dir: "{{ COMMON_LOG_DIR }}/{{ discovery_service_name }}"
 discovery_debian_pkgs:
   - libmysqlclient-dev
   - libssl-dev
+  - libffi-dev  # Needed to install the Python cryptography library for asymmetric JWT signing
 
 discovery_redhat_pkgs: []