salt-cloud-reactor

This is a reactor formula, which allows supported providers in Salt Cloud to notify Salt when an instance is created, so that it may be automatically bootstrapped and accepted by the Salt Master, or when an instance is deleted, so that its key can be automatically removed from the Salt Master.

Dependencies

The following packages must be installed:

- Salt (develop branch)

Master Configuration

The following files need to be configured on the Salt Master:

- /etc/salt/master
- /etc/salt/cloud
- /etc/salt/cloud.providers.d/*

/etc/salt/master

The master must be set up to point the reactor to the necessary Salt Cloud provider setting. Any additional settings to be used on the target minion, that are not configured in the provider configuration, can also be set here.

reactor:
  - 'salt/cloud/*/cache_node_new':
    - '/srv/reactor/autoscale.sls'
  - 'salt/cloud/*/cache_node_missing':
    - '/srv/reactor/autoscale.sls'

autoscale:
  provider: my-ec-config
  ssh_username: root

/etc/salt/cloud

Salt Cloud must be configured to use the cloud cachedir, and to generate events based on the contents of it. The following two options need to be set:

update_cachedir: True
diff_cache_events: True

This will cause Salt Cloud to fire events to Salt when changes are detected on the configured provider.

Some of these events will contain data which describe a node. Because some of the fields returned may contain sensitive data, the cache_event_strip_fields configuration option exists to strip those fields from the event return.

cache_event_strip_fields:
  - password
  - priv_key

/etc/salt/cloud.providers.d/*

Existing Salt Cloud provider configuration can be used with this reactor. Profile configuration is not necessary on the master; the instance is assumed to already be created by the time it hits the reactor.

my-ec2-config:
  id: <aws id>
  key: <aws key>
  keyname: <my key name>
  securitygroup: <my security group>
  private_key: </path/to/my/priv_key.pem>
  location: us-east-1
  provider: ec2
  minion:
    master: saltmaster.example.com

Basic Usage

Once the Salt Master has been configured, the reactor will manage itself. When salt-cloud -F or salt-cloud --full-query is issued against a configured provider, the cloud cache will up reviewed and updated by Salt Cloud. When a new instance is detected, Salt Cloud will be notified to wait for it to become available, and bootstrap it with Salt. Its key will be automatically accepted, and if the minion configuration includes the appropriate startup state, then the minion will configure itself, and go to work.

When the autoscaler spins down a machine, the Wheel system inside of Salt will be notified to delete its key from the master. This causes instances to be completely autonomous, both in setup and tear-down.

In order to perform these queries on a regular basis, the above command needs to be issued via a scheduling system, such as cron or the Salt Scheduler. It is recommended in most configuration to use no less than a 5 minute delay between intervals, as a measure of respect to the cloud provider.

Caveats

Because this data is polled for, rather than being triggered directly from the cloud provider, there will be a delay between the instance being created, and Salt Cloud being able to bootstrap it.