Awesome

mcrouter-k8s-provisioner

A mechanism to automatically configure Facebook's Mcrouter based on adding/removing memcached pods.

In simple terms, it'll automatically re-create the mcrouter config file for a bunch of memcached instances managed through a Kubernetes deployment. The information for which memcached instances are available to put into the config is extracted via DNS lookup in Kubernetes.

FIXME

Make sure we also trap the port

Usage

Please see the example directory to see how this all works.

Pre-conditions:

• You have deployed the persistent volume
• You have deployed the persistent volume claim

If you don't have an NFS server available for testing, you can use the example nfs-server. Make sure you modify the persistent volume to use the correct IP.

First, deploy the mcrouter-provisioner - it'll mount the volume, create an empty config, and start listening for pod creation/removal events. As memcached pods come online, it'll grab their info and update the mcrouter config file. We are using a deployment as we want to ensure that one instance is always running.

Second, deploy a bunch of memcached nodes using a deployment and a headless service. We specifically want the headless service so that we can look up all the nodes in Kubernetes' DNS.

Last, setup a Kubernetes deployment using jamescarr/mcrouter as the image, this time with a proper service. These nodes all need a persistent volume to read the same configuration file from. When you build a service that requires memcached, you will point it to this service, and one of the mcrouter instances will handle the request and route to one of the memcached instances appropriately.

Developing

Make sure you have the dep tool installed:

go get -u github.com/golang/dep/...

Next, make sure you install the dependencies we need:

dep ensure

Finally, build the app:

go build -o mcrouter-k8s-provisioner main.go