cortex: The -target=all flag does not include alertmanager

I’m running a 3 host cluster with 1.3.0-rc.1 and I’m trying to run Alertmanager serivce with the following config:

alertmanager:
  external_url: 'https://alerts.example.org/'
  cluster_bind_address: '10.1.33.0:9094'
  cluster_advertise_address: '10.1.33.0'
  data_dir: '/var/tmp/cortex/alertmnanager'
  retention: 120h
  storage:
    type: local
    local:
      path: '/var/tmp/cortex/alerts'

But I don’t see the service listening on port 9094 at all:

admin@master-03.do-ams3.metrics.hq:~ % sudo netstat -lpnt | grep cortex
tcp        0      0 10.1.33.0:9095          0.0.0.0:*               LISTEN      27780/cortex        
tcp6       0      0 :::9092                 :::*                    LISTEN      27780/cortex 

And I don’t see the service in the return value from /services:

 % curl -s http://10.1.33.0:9092/services | grep -A1 '<tr>' | grep td
					<td>memberlist-kv</td>
					<td>store</td>
					<td>server</td>
					<td>ring</td>
					<td>distributor</td>
					<td>ingester</td>
					<td>query-frontend</td>
					<td>querier</td>
					<td>ruler</td>
					<td>table-manager</td>

Both configured directories exist and are owned by service user. I’m not sure what more I’m supposed to do.