Category Archives: Kubernetes

Kubernetes is an open-source container orchestration system for automating application deployment, scaling, and management.

Kubernetes: Service, load balancing, kube-proxy, and iptables

1 November 2020
 

 One day I wondered – how is load balancing between pods is working in Kubernetes? I.e. – we have an external Load Balancer. Then a Service. And behind it – Pods. What happens when we are receiving a network packet from the world, and we have a few pods – how the traffic will be… Read More »

Kubernetes: running SQL migrations with Kubernetes Job and Helm hook

27 October 2020
 

 We have a project running in Kubernetes that needs to run SQL migrations during deployment. To run migrations need to clone a Github repository and run actually migrations stored in it. Currently, this is done with Kubernetes initContainers , and there are two of them – the first one with git clones the repository with… Read More »

Helm: reusable chart – named templates, and a generic chart for multiple applications

20 October 2020
 

 Our project is growing, and more and more applications are started on the AWS Elastic Kubernetes Service. Finally, we’ve faced with the question already mentioned in the Helm: пошаговое создание чарта и деплоймента из Jenkins (Rus) – what to do with Kubernetes manifests and Helm templates when using a lot of similar applications? Especially now,… Read More »

Kubernetes: AWS ALB Ingress Controller – add redirect to another domain

9 October 2020
 

 We have an application – an old version, and a new one, and two domains for them. The application is working on AWS Elastic Kubernetes Service, behind an AWS LoadBalancer created with AWS ALB Ingress Controller. The task is to create a redirect from the old domain’s Ingress to a new LoadBalancer: old URL: dev.api.old-example.com… Read More »

Kubernetes: Evicted pods and Pods Quality of Service

3 October 2020
 

 We have a Kubernetes cluster running on AWS Elastic Kubernetes Service. In this cluster, we have an application which is usually working fine but sometimes our monitoring system notifies about unhealthy pods: Check pods: [simterm] $ kk -n eks-prod-1-web-projectname-admin-backend-ns get pod NAME READY STATUS RESTARTS AGE bttrm-web-projectname-admin-backend-64648597fc-9j29n 1/1 Running 0 43m bttrm-web-projectname-admin-backend-64648597fc-kptjj 1/1 Running 0… Read More »

Redis: running Master-Slave replication in Kubernetes

29 September 2020
 

 The task is to spin up a Redis instance in a Kubernetes cluster. Will use the Master-Slave replication setup with Sentinels for monitoring and failover operations. Check the Redis: replication, part 2 – Master-Slave replication, and Redis Sentinel post for more details. Redis cluster vs Redis replication See Redis: replication, part 1 – an overview.… Read More »

AWS Elastic Kubernetes Service: load-testing and high-load tuning – problems and solutions

4 September 2020
 

 Actually, this post was planned as a short note about using NodeAffinity for Kubernetes Pod: But then, as often happens, after starting writing about one thing, I faced another, and then another one, and as a result – I made this long-read post about Kubernetes load-testing. So, I’ve started about NodeAffinity, but then wondered how… Read More »

Kubernetes: a cluster’s monitoring with the Prometheus Operator

13 August 2020
 

 Continuing with the Kubernetes: monitoring with Prometheus – exporters, a Service Discovery, and its roles, where we configured Prometheus manually to see how it’s working – now, let’s try to use Prometheus Operator installed via Helm chart. So, the task is spin up a Prometheus server and all necessary exporter in an AWS Elastic Kubernetes… Read More »

Kubernetes: HorizontalPodAutoscaler – an overview with examples

12 August 2020
 

 Kubernetes HorizontalPodAutoscaler automatically scales Kubernetes Pods under ReplicationController, Deployment, or ReplicaSet controllers basing on its CPU, memory, or other metrics. It was shortly discussed in the Kubernetes: running metrics-server in AWS EKS for a Kubernetes Pod AutoScaler post, now let’s go deeper to check all options available for scaling. For HPA you can use three… Read More »