Add stx-update to devstack plugin dependency list

Add the minimum dependency bits for devstack master, plus the
required stx-update plugin in the devstack job definition.

The remaining master/bionic stuff will be in a follow-up review.

Change-Id: Id6b4e3dad1fe54d66b2b5a3dbbe3983621943bb2
Signed-off-by: Dean Troyer <dtroyer@gmail.com>

.zuul.yaml

@@ -94,6 +94,7 @@
     timeout: 7800
     required-projects:
       - openstack/stx-fault
+      - openstack/stx-update
     vars:
       tox_envlist: functional
       devstack_services:
@@ -132,5 +133,6 @@
       devstack_plugins:
         stx-fault: git://git.starlingx.io/stx-fault
         stx-nfv: git://git.starlingx.io/stx-nfv
+        stx-update: git://git.starlingx.io/stx-update
       devstack_localrc:
         LIBS_FROM_GIT: keystone

devstack/settings

@@ -1,6 +1,12 @@
 #!/bin/bash
 # Devstack settings
 
+# This plugin enables StarlingX stx-update services and follows the
+# DevStack plugin contract:
+# https://docs.openstack.org/devstack/latest/plugins.html#plugin-sh-contract
+
+# Services
+
 # Defaults
 # --------
 
@@ -9,6 +15,11 @@ STX_NFV_NAME=stx-nfv
 ######### Plugin Specific ##########
 enable_service $STX_NFV_NAME
 
+# This must not use any variables to work properly in OpenStack's DevStack playbook
+define_plugin stx-nfv
+# This works for Zuul jobs using OpenStack's DevStack roles
+plugin_requires stx-nfv stx-update
+
 if is_service_enabled stx-nfv; then
     # Enable prerequisites here
     :