Internal Load Balancing on VPC tiers

Introduction

This documents gives an overview to the design and functional implementation for Internal Load Balancing on VPC tiers.

Feature developers:

• APIs and Orchestration level - Alena Prokharchyk
• Backend - to be assigned

Use case

There are 2 tiers in the VPC - Web tier A and Application tier B. Traffic to Web tier is balanced on the VPC VR on the public side. Admin wants traffic coming from LB to App tier to be balanced as well. Load balancing on the APP tier will be covered by the Internal LB feature.

The general flow

Internal LB gets created on the tier B. Access from tier A to tier B can be managed by Network ACLs.

Create tier B using network offering with Service=Lb, Provider=InteralLBVm

Acquire guest IP address from the tier B

Create Internal Load Balan

API and orchestration level

New APIs:

• createInternalLoadBalancerRule (has all parameters listed in our regular createLBRule api except for the publicIpId). NetworkId will be required.
• deleteInternalLoadBalancerRule
• listInternalLoadBalancerRules

create/list APIs should return IP that is acquired automatically as a part of LB creation.

Existing LB APIs should be supported to add user vms to the LB.

•  assignToLBRule
•  removeFromLBRuleAs we are going to support LB on the public side on the VPC with the VPC VR as a provider, so we need a separate service/provider to support internal LB on the VPC - InternalLb service and InternalLb provider. Have to define these providers in the VPC offering as well as on the Network offering.

DB

New tables

TBD

Upgrade 

Either have to upgrade existing default VPC/Network offering with the new Provider for LB service, or create a new default one having Internal LB provider in place.

Backend

TBD by the backend engineer

Limitations

• Internal and Public Lb are mutually exclusive on a tier. If the tier has LB on the public side, then it can't have the Internal LB

UI

TBD