Nitrox

Configure Citrix NetScaler loadbalancing for container platforms such as Docker Swarm, Mesos Marathon, Kubernetes and Consul.

Theory of Operation

1. Containers that form a load-balanced backend for an app/microservice are labeled with the same label (e.g., com.citrix.lb.appname=AccountService, or AccountService) or name
2. Information (host IP and port) from the container platform (such as Docker Swarm) API for the labeled containers are used to configure a NetScaler loadbalancer.
3. The NetScaler admin creates the "frontend" lb vserver with the label/name used in #1

NetScaler Pre-requisites

1. Credentials for a running Citrix NetScaler (VPX/MPX/SDX/CPX). On the host where you run the container/code, replace with your own:

   export NS_IP=10.220.73.33
   export NS_USER=nsroot
   export NS_PASSWORD=useyourownnspassword
   

2. List of microservices / apps that have to be load balanced. For example, 'AccountService', 'ProductCatalog', 'ShoppingCart', etc.

3. NetScaler that has been configured with VIP(s) for above apps. For example, lets say there is a microservice/app called 'AccountService' with a load balanced IP of 10.220.73.222. On the NetScaler:

   add lb vserver AccountService HTTP 10.220.73.222 80 -persistenceType COOKIE -lbMethod LEASTCONNECTION
   

   Alternatively, if the lb_ip and lb_port are included in the APP_INFO env variable, the lb vserver is configured automatically with some default options (ROUNDROBIN)

4. (for developers) The NetScaler Python SDK (can be downloaded here https://www.citrix.com/downloads/netscaler-adc/sdks.html or copied from the NetScaler)

#Container Platforms

Docker Swarm

[Docker Swarm] (https://docs.docker.com/swarm/) is a clustered container manager. Instructions are here

Marathon

[Marathon] (https://mesosphere.github.io/marathon/) is a PAAS framework that can run containerized workloads. Instructions are here

Kubernetes

[Kubernetes] (https://kubernetes.io/) is an open source orchestration system for Docker containers. It . Instructions are here

Consul-template

[consul-template] (https://github.com/hashicorp/consul-template) provides a convenient way to populate values from Consul. Instructions are here