Docker Engine from Docker, Inc has been at forefront of technology, when it comes to containers. It was so synonymous with containers, that docker and containers used to mean the same thing for a long time. It used to be so till the time Kubernetes and OCI came and confusion has taken over since. However, Docker Engine contains so many UX enhancements, that it feels like magic till today and still a recommended option for anyone starting to get their hands dirty in container technology. What we call Docker Engine or simply docker, is composed of many small components tied together like a car engine. Note that Docker Engine is further a small component in set of tools included in the Docker Desktop, which in itself is a separate world.Read More »
In the Kubernetes release v1.20, the development team has marked dockershim as deprecated. There was initially some shock and confusion, as it was perceived that team is moving away from docker completely, however that is not the case. As its turns out, what the team is doing, is steering the Kubernetes away from the proprietary parts of Docker or Docker Engine or just simply called Docker. The Docker Engine is further comprised of many different sub-components like dockerd, containerd, runc etc., many of which were initially developed by Docker Inc and then given away to community. These were later standardized and maintained by the community.
The Kubernetes community has written a detailed blog post about deprecation with a dedicated FAQ page for it. This blog post is being written to understand the impact and what needs to be done about it. Depending on how do you use Docker, think and understand about it, you may or may not have to do anything about it or get worried about sleepless nights.Read More »
Bash scripting has many special shell variables like
$?, etc. to help users write more powerful and versatile scripts. One can code for many scenarios, using these shell variables, which are otherwise not possible.
One of the common requirements is to write a more generic code and run it specifically using the arguments supplied at the run time. Since script users can’t be always trusted with supplying all arguments properly, its beneficial to adjust script to properly check for conditions like how many arguments are supplied, if arguments are proper, etc. Since bash also does not natively offer a way to write parameters for the scripts, you also need to process the arguments in the correct order. For this, bash offers special variables
$9 as positional parameters.
In first part of this post, we setup WSL2, Docker Desktop, Enabled Integration of WSL2 with Docker, Setup KinD cluster and spin up a single node and multi node cluster. Since 6 nodes HA cluster was too much for our learning needs, lets first delete it using
kind delete cluster --name multicluster and provision a fresh single node cluster for us.
Setup Kubernetes Dashboard
Some people like to see using visual mode, to get on started with things. For this, we can use Kubernetes Dashboard. To set it up, we can use below commands:Read More »
Kubernetes has raced ahead of other container management platforms in last few years. However there remain difficulties in setup and running multi node clusters for developers to test their container workloads. Many organizations come around this by provisioning separate kubernetes clusters for devs. Some other go to the extent of provisioning one kubernetes cluster per developer. However it soon becomes additional hassle for devs and ops alike and also keeps contributing to company’s rising cost.
Minikube is one of solutions that can be used to solve this scenario but minikube is limited to single node setup. But to gain Kubernetes experience, most need to run multi node solutions or clusters. KinD is a tool which can be used for running local Kubernetes clusters using Docker container nodes. KinD was primarily designed for testing Kubernetes itself, but may be used for local development or CI.Read More »
Podman is a daemonless container engine for developing, managing, and running Open Container Initiative (OCI) containers and container images on your Linux System. It is an open-source project that is available on most Linux platforms and resides on GitHub. Containers under the control of Podman can either be run by root or by a non-privileged user. Podman provides a docker engine compatible command interface and most of the commands can simply be used by
alias docker=podman for experience professionals on docker. However, that said, Podman is not a replacement of dockerd, docker compose and docker swarm yet. In this post, we’ll learn the basic operations with Podman as container engine.
history command utility in Linux is already nice, it would have been great if we can have timestamp to understand when certain commands were run. This is particularly useful for organizations, that needs to match certain audit requirements. We can easily configure timestamps by using HISTTIMEFORMAT environmental variable in following way:
HISTTIMEFORMAT="%d/%m/%y %T " # for e.g. "13/03/21 15:59:59" HISTTIMEFORMAT="%F %T " # for e.g. "2021-03-13 15:59:59"
Every system admin in this world has ran into problem of calculating IP address range, network masks, usable IP addresses, etc. for one or the other reason. It is very important part of networking related operations and what a server would be without any clients or IP addresses. Some people consider it so important, they expect you to do calculations like these in your mind in your job interviews. There are also various websites online to just run CIDR calculations. However its all additional steps and a hassle.
Fortunately, if you are a linux user, you can make life easy for yourself by using utility
sipcalc. It is a simple command line tool which is available in epel repo.