Demo of Citrix NetScaler CPX configuration driven from Consul

Developers need control at layer 7 for the ingress traffic for their application. Either their load balancer (AWS ELB) doesn't have all the features (routing / filtering / auth / redirection) or their ops team controls a very capable load balancer (NetScaler MPX) that cannot be configured by developers. One solution is to operate a second layer of load balancing ("Software LB or SLB) under developer control. This can be for example using Netflix Zuul. This demo shows how the NetScaler CPX (containerized NetScaler) can be used to form the SLB layer.

Designed to run on your laptop, this demo shows NetScaler CPX can be used as the SLB for your backend (Dockerized) microservices. If you are running on a Windows laptop you will need to set an environment variable for HOST_IP to be either local host or the IP address of your DockerNAT. The current Docker-compose file is pointed to 12.0-56.20. This should pull down automatically, but if that release is updated and no longer available you will need to update that to the latest release.

Service discovery is driven by Registrator and Consul. Routes discovered from Consul are configured using a sidecar container. The sidecar uses the NetScaler's REST API to configure the CPX.

This was demo'ed at DockerCon 2017 (April 19)

Asciicast

Pre-requisites

• NetScaler CPX Express image (from Citrix or microloadbalancer.com )
• Docker on Windows or Mac (tested with Mac v17.04.0-ce-mac7)
• Gnu Make if you want to skip the typing and use the Makefile

Demo steps (Quick, but small chance of failure)

(OPTIONAL, for the pants-on-fire folks). If you have GNU Make, you can speed through the steps below by:

make all
make print_urls

Access the microservices from a browser using the URLs above. Scale the microservices up or down and refresh the browser

cd app
docker-compose scale catalog=2 cart=4
docker logs cpx-sidecar

Demo steps (step-by-step so you can build your own awesome demo)

• Pull the following docker images:

  • Consul : docker pull consul
  • Registrator : docker pull registrator

• Build the following microservice images:

  • Login: (cd loginjs; docker build -t login-service .)
  • Cart: (cd cartjs; docker build -t cart-service .)
  • Catalog: (cd catalogjs; docker build -t catalog-service .)

• Build the sidecar image

  • docker build -t cpx-consul-sidecar .

• Determine your LAN IP. E.g., on a Mac:

export HOST_IP=$(ifconfig en0 | grep "inet "| awk -F" " '{print $2}')

This is used to point registrator and the CPX sidecar to the Consul server (in this demo Consul also runs locally)

• Run Consul

docker run --name consul -d -p 8400:8400 -p 8500:8500 -p 8600:53/udp -h $HOST_IP consul

• Run registrator

docker run   --net=host --name registrator   -d -h $HOST_IP  -v /var/run/docker.sock:/tmp/docker.sock  gliderlabs/registrator -cleanup -resync 5 consul://localhost:8500

Note that registrator "discovers" the consul container and populates the consul registry with the "consul service". You can view the Consul ui using a browser at http://localhost:8500/

• Register routes in Consul for each of the microservices (login, cart and catalog)

docker run --net=host consul kv put widgetshop/services/login-service/route "/api/login/*"
docker run --net=host consul kv put widgetshop/services/cart-service/route "/api/cart/*"
docker run --net=host consul kv put widgetshop/services/catalog-service/route "/api/catalog/*"

• Run the microservices using Docker Compose:

(cd app; docker-compose up -d)

• Run CPX and the sidecar

docker-compose up -d

• Check the logs of the sidecar:

docker logs cpx-sidecar

• Use a browser to access the microservices

echo "The urls are"
echo "http://localhost:$(docker port cpx 8088|awk -F':' '{print $2}')/api/catalog/"
echo "http://localhost:$(docker port cpx 8088|awk -F':' '{print $2}')/api/cart/"
echo "http://localhost:$(docker port cpx 8088|awk -F':' '{print $2}')/api/login/"

• Access the microservices from a browser using the URLs above. Scale the microservices up or down and refresh the browser

cd app
docker-compose scale catalog=2 cart=4
docker logs cpx-sidecar

Cleanup

make cleanup or

docker-compose down
(cd app; docker-compose down)
docker stop registrator
docker stop consul
docker rm registrator
docker rm consul
docker rmi login-service
docker rmi cart-service
docker rmi catalog-service
docker rmi cpx-consul-sidecar

TODO

• Service names are hardcoded in sidecar. Import them from the environment or read from Consul.