Signaling SoftwareDeployment resources via Swift

https://blueprints.launchpad.net/heat/+spec/software-config-swift-signal

Currently the only option for signaling a deployment resource requires making an authenticated API request to heat. A SoftwareDeployment resource signal_transport: TEMP_URL_POLL will allow unauthenticated signaling using a similar approach to OS::Heat::SwiftSignal.

Problem description

OS::Heat::SoftwareDeployment signal_transport options currently both require resource scoped credentials and network connectivity from the server to a heat API to work.

Proposed change

Like OS::Heat::SwiftSignal, signal_transport:TEMP_URL_POLL would create a long-lived swift TempURL which is polled by heat until the object contains the expected data from the nova server performing the configuration deployment. Initially, “long-lived” will mean expiring in year 2038.

Implementing a signal_transport:TEMP_URL_POLL would have the following benefits:

  • Each OS::Heat::SoftwareDeployment resource would not need to create a stack user
  • Making swift objects accessible from nova servers is more likely to be provided for by the cloud operator, compared to access to keystone and heat APIs.

Also, heat.conf default_software_config_transport option will be added so that operators can choose the most appropriate transport for their cloud. Choosing the default will depend on whether the cloud supports keystone v3, swift and the cloudformation endpoint.

Alternatives

Blueprint software-config-zaqar will implement signal_transport:ZAQAR_MESSAGE which would be the preference for clouds which offer a zaqar endpoint. Since Swift is much more widely deployed than Zaqar then ZAQAR_MESSAGE should be recommended first, followed by TEMP_URL_POLL.

Implementation

Assignee(s)

Primary assignee:
<steve-stevebaker>

Milestones

Target Milestone for completion:
Kilo-3

Work Items

  • Implement TempURL creation and polling in SoftwareDeployment
  • Implement TempURL POSTing in heat-templates 55-heat-config (may not be required if interface is identical to CFN_SIGNAL)
  • Document implications for using TEMP_URL_POLL and AUTO in the software-deployment section of the hot-guide.

Dependencies

No dependencies on new libraries or existing blueprints.