Resources QoS in Kubernetes


I extracted a few points to grasp the rough idea of how Kubernetes manages resources QoS: Pods that need to stay up reliably can request guaranteed resources, while pods with less stringent requirements can use resources with weaker or no guarantee. If a pod is successfully scheduled, the container is guaranteed the amount of resources … Continue reading Resources QoS in Kubernetes

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Missing Parts of OpenShift Dedicated


I have been working on OpenShift Dedicated (on AWS) for a few weeks. At the time of writing (v3.5.5.31), here are a couple missing parts that I have found out so far. They are all confirmed by the RedHat support. Share persistent volume across multiple containers: Currently there is no way to share the persistent … Continue reading Missing Parts of OpenShift Dedicated

Huggies – AWS Elastic Beanstalk Automation Tool


Huggies is a side project that I started when working for the NAPI team which pronounced as ['næpɪ], and that is why I named it as Huggies 😉 The team's environments are mostly on AWS Elastic Beanstalk. In general, Elastic Beanstalk is a good tool as it abstracts the complexicity of managing Elastic Load Balancer, … Continue reading Huggies – AWS Elastic Beanstalk Automation Tool

Run Elasticsearch Cluster on Spot Instances


Running Elasticsearch cluster is not cheap, as it generally requires a couple of high spec servers to provides both performances and reliabilities. Below is a typical 3 nodes Elasticsearch cluster that is running on AWS: 3 nodes, one in each availability zone. each node is both master and data node, and it is formed by ec2 … Continue reading Run Elasticsearch Cluster on Spot Instances

Hourly Intermittent Elastic Beanstalk Service Interruption


We noticed that one of our Java applications that is deployed on Elastic Beanstalk has hourly service interruption. Each outage only lasts for about 40 - 60 seconds. By looking at the CloudWatch, the ELB has intermittent 5xx errors every one hour, like 09:01, 10:01, 11:01 ... After some investigations, I found it out that it … Continue reading Hourly Intermittent Elastic Beanstalk Service Interruption

Double SSH Hops example


Client -ssh only--> Jumpbox00 -ssh only--> Jumpbox01 --http only-> Internal network Here is how to ssh to jumpbox01, and visit websites in internal networks from Client. 1) Ensure you have a private key that is trusted by both jumpbox00 and jumpbox01. For example, jb.pem under ~/.ssh/, then run the following command: ssh-add ~/.ssh/jb.pem  2) Add the following … Continue reading Double SSH Hops example