Category Archives: Containers

Devops with Kubernetes

I did the following presentation “Devops with Kubernetes” in Kubernetes Sri Lanka inaugural meetup earlier this week. Kubernetes is one of the most popular open source projects in the IT industry currently. Kubernetes abstractions, design patterns, integrations and extensions make it very elegant for Devops. The slides delve little deep on these topics.

NEXT 100 Webinar – Top 3 reasons why you should run your enterprise workloads on GKE

I presented this webinar “Top 3 reasons why you should run your enterprise workloads on GKE” at NEXT100 CIO forum earlier this week. Businesses are increasingly moving to Containers and Kubernetes to simplify and speed up their application development and deployment. The slides and demo covers the top reasons why Google Kubernetes engine(GKE) is one of the best Container management platforms for enterprises to deploy their containerized workloads.

Following are the slides and recording:

Recording link



Docker Networking Tip – Troubleshooting

Debugging Container and Docker Networking issues can be daunting at first considering that containers do not contain any debug tools inside the container. I normally see a lot of questions around Docker networking issues in Docker and stackoverflow forum. All the usual networking tools can be used to debug Docker networking, it is just that the approach taken is slightly different. I have captured my troubleshooting steps in a video and a presentation.

Following is the video and presentation of my Docker Networking troubleshooting tips.

I would appreciate if you can provide me feedback if the Networking tip videos were useful to you. Also, if there are any other Docker Networking topics that you would like to see as a tip video, please let me know.

I have also put few Docker Networking videos and presentations that I did over last 3 months below for completeness.

Following are the 2 previous Networking tip videos.

Following are 2 Docker Networking deep dive presentations:

Docker features for handling Container’s death and resurrection

Docker containers provides an isolated sandbox for the containerized program to execute. One-shot containers accomplishes a particular task and stops. Long running containers runs for an indefinite period till it either gets stopped by the user or when the root process inside container crashes. It is necessary to gracefully handle container’s death and to make sure that the Job running as container does not get impacted in an unexpected manner. When containers are run with Swarm orchestration, Swarm monitors the containers health, exit status and the entire lifecycle including upgrade and rollback. This will be a pretty long blog. I did not want to split it since it makes sense to look at this holistically. You can jump to specific sections by clicking on the links below if needed. In this blog, I will cover the following topics with examples:

Handling Signals and exit codes

Continue reading Docker features for handling Container’s death and resurrection

Compare Docker for Windows options

As part of Dockercon 2017, there was an announcement that Linux containers can run as hyperv container in Windows server. This announcement made me to take a deeper look  into Windows containers. I have worked mostly with Linux containers till now. In Windows, I have mostly used Docker machine or Toolbox till now. I recently tried out other methods to deploy containers in Windows. In this blog, I will cover different methods to run containers in Windows, technical internals on the methods and comparison between the methods. I have also covered Windows Docker base images and my experiences trying the different methods to run Docker containers in Windows. The 3 methods that I am covering are Docker Toolbox/Docker machine, Windows native containers, hyper-v containers.

Docker Toolbox

Docker Toolbox runs Docker engine on top of boot2docker VM image running in Virtualbox hypervisor. We can run Linux containers on top of the Docker engine. I have written few blogs(1, 2) about Docker Toolbox before. We can run Docker Toolbox on any Windows variants.

Windows Native containers

Continue reading Compare Docker for Windows options

Kubernetes CRI and Minikube

Kubernetes CRI(Container runtime interface) is introduced in experimental mode in Kubernetes 1.15 release. Kubernetes CRI introduces a common Container runtime layer that allows for Kubernetes orchestrator to work with multiple Container runtimes like Docker, Rkt, Runc, Hypernetes etc. CRI makes it easy to plug in a new Container runtime to Kubernetes. Minikube project simplifies Kubernetes installation for development and testing purposes. Minikube project allows Kubernetes master and worker components to run in a single VM which facilitates developers and users of Kubernetes to easily try out Kubernetes. In this blog, I will cover basics of Minikube usage, overview of CRI and steps to try out CRI with Minikube.


Kubernetes software is composed of multiple components and beginners normally get overwhelmed with the installation steps. It is also easier to have a lightweight Kubernetes environment for development and testing purposes. Minikube has all Kubernetes components in a single VM that runs in the local laptop. Both master and worker functionality is combined in the single VM.

Following are some major features present in Minikube:

Continue reading Kubernetes CRI and Minikube

Docker 1.13 Experimental features

Docker 1.13 version got released last week. Some of the significant new features include Compose support to deploy Swarm mode services, supporting backward compatibility between Docker client and server versions, Docker system commands to manage Docker host and restructured Docker CLI. In addition to these major features, Docker introduced a bunch of experimental features in 1.13 release. In every release, Docker introduces few new Experimental features. These are features that are not yet ready for production purposes. Docker puts out these features in experimental mode so that it can collect feedback from its users and make modifications when the feature gets officially released in the next set of releases. In this blog, I will cover the experimental features introduced in Docker 1.13.

Following are the regular features introduced in Docker 1.13:

  • Deploying Docker stack on Swarm cluster with Docker compose.
  • Docker cli with Docker daemon backward compatibility. This allows newer Docker CLI to talk to older Docker daemons.
  • Docker cli new options like “docker container”, “docker image” to collect related commands in docker sub-keyword.
  • Docker system details using “docker system” – This helps in maintaining Docker host for cleanup and to get Container usage details
  • Docker secret management
  • docker build with compress option for slow connections

Following are the 5 features introduced in experimental mode in Docker 1.13:

  • Experimental daemon flag to enable experimental features instead of having separate experimental build.
  • Docker service logs command to view logs for a Docker service. This is needed in Swarm mode.
  • Option to squash image layers to the base image after successful builds.
  • Checkpoint and restore support for Containers.
  • Metrics (Prometheus) output for basic container, image, and daemon operations.

Experimental Daemon flag

Docker released experimental features prior to 1.13 release as well. In earlier release, users needed to download a new Docker image to try out experimental features. To avoid this unnecessary overhead of having different images, Docker introduced a experimental flag or option to Docker daemon so that users can start the Docker daemon with or without experimental features. With Docker 1.13 release, Docker experimental flag is in experimental mode.

By default, experimental flag is turned off. To see the experimental flag, check Docker version.

Continue reading Docker 1.13 Experimental features