Chapter 5. Automation with Ansible

Ansible provides an easy to implement automation mechanism for various physical as well as virtual network functions using protocols such as netconf or cli. As currently used in ONAP under APPC architecture, Ansible provides the VNF management framework that enables an almost CLI like set of tools in a structured form. It is agentless, which means that the target VNF does not require any additional software. This construct enables management of any VNF in a consistent manner whether it supports a standard interface or protocol such as netconf or not. Any action (for example configure, restart, and health check) can be executed on the VNF by constructing a playbook (or set of playbooks) that is executed by an Ansible on the VNF through SSH.

The Ansible Extension for APP-C allows management of VNFs through the following architecture:

  • Ansible Directed Graph (DG) - The Ansible Directed graph is a generic directed graph that you can use to invoke any playbook through Ansible (and therefore any APP-C action, since in Ansible, VNF actions map to playbooks) corresponding to an LCM action.
  • APP-C Ansible Adapter - The ansible adapter is an OSGI bundle in the APP-C Karaf container that interacts with the Ansible server. It is a set of REST calls that performs two actions. It first submits a request for a playbook to be executed, and second, if required it gets the results of the playbook after execution (if in synchronous mode).
  • APP-C/Ansible server interface - Ansible libraries are written in Python and therefore cannot be executed natively from within the APP-C Karaf container. Instead, the design calls for an Ansible Server that can execute the Ansible playbooks and exposes a REST interface that is compliant with requirements of APP-C. These requirements are documented as the Server API Interface that any compliant Ansible Server must support. Exact implementation of the Ansible Server is left open and does not affect APP-C operations as long as the server follows the interface. For purposes of evaluation, a reference web server that implements this APP-C/Ansible Server interface has been developed and the code is available from the App-C ONAP repository under the appc-adapters/appc-ansible-adapter/appc-ansible-example-server path.

For an illustration of the workflow when an application controller receives an event, see the APPC Ansible Adapter page.