Showing posts from 2017

Save greenbacks on Google Container Engine using autoscaling and preemptible VMs

There is an awesome new feature on Google Container Engine (GKE) that lets you combine autoscaling, node pools and preemptible VMs to save big $!

The basic idea is to create a small cluster with an inexpensive VM type that will run 7x24. This primary node can be used for critical services that should not be rescheduled to another pod. A good example would be a Jenkins master server. Here is an example of how to create the cluster:

gcloud alpha container clusters create $CLUSTER \ --network "default" --num-nodes 1 \ --machine-type ${small} --zone $ZONE \ --disk-size 50
Now here is the money saver trick:  A second node pool is added to the cluster. This node pool is configured to auto-scale from one node up to a maximum. This additional node pool uses preemptible VMs. These are VMs that can be taken away at any time if Google needs the capacity, but in exchange you get dirt cheap images. For example, running a 4 core VM with 15GB of RAM for a month comes in under $30.

Automating OpenDJ backups on Kubernetes

KubernetesStatefulSets are designed to run "pet" like services such as databases.  ForgeRock's OpenDJ LDAP server is an excellent fit for StatefulSets as it requires stable network identity and persistent storage.

The ForgeOps project contains a Kubernetes Helm chart to deploy DJ to a Kubernetes cluster. Using a StatefulSet, the cluster will auto-provision persistent storage for our pod. We configure OpenDJ to place its backend database on this storage volume.

This gives us persistence that survives container restarts, or even restarts of the cluster. As long as we don't delete the underlying persistent volume, our data is safe.

Persistent storage is quite reliable, but we typically want additional offline backups.

The high level approach to accomplish this is as follows:
Configure the OpenDJ container to support scheduled backups to a volume.Configure a Kubernetes volume to store the backups.Create a sidecar container that archives the backups.  In this example we wi…