Melange is intended to provide network information services for use across OpenStack services. The initial focus will be on IP address management (IPAM) and DHCP functionality. Melange is intended to be a standalone service with it's own API. However, the initial use case will be to decouple existing IP management and dns_masq functionality from Nova and support the existing Nova networking functionality.
Longer term, Melange will evolve to integrate with other OpenStack services, particularly the Quantum service (virtual network segments), network containers and Load Balancer as a Service (LBaaS). It is also anticipated that we may evolve beyond basic IP address management and DHCP to handle other network information such as gateway, routing and DNS information.
Since Melange will initially focused on decoupling IPAM and DHCP from Nova. We plan to implement this within the Nova project and repository. Since Melange will be a separate service and API. This effort will not have any direct impact on Nova. However, the eventual adoption of this service is dependent on the network refactoring work in the following blueprint:
This blueprint is the umbrella for the overall Melange service. The specific implementation details are further identified in the following dependent blueprints:
IP addresses are an important resource for a cloud provider to manage, and providers will need flexibility in how addresses are assigned to VMs and other networking-related services (e.g., load balancing devices). The existing IP association mechanism is tightly coupled to Nova's network provisioning mechanism, including a networking host that provides NAT and may not work well with a providers network design. Additionally, customers may want to assigned their own addresses, for example, isolated tenant networks that use RFC 1918 space or have a VPN to a network at a remote site).
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Much of the background behind the creation of Melange can be found on the Network Service http://etherpad.openstack.org/6LJFVsQAL7, Etherpad discussion.