Docker Swarm is comparatively easier to maintain compared to Kubernetes so I was thinking of migrating from a Kubernetes cluster to a Docker Swarm cluster.
In my Kubernetes cluster, I used Jobs extensively to spin up workers ad-hoc and is very critical to the main functions of the whole infrastructure. Best thing about Kubernetes Jobs is that they will shut down after a certain time limit after Job completion and recycle the resources.
I want to ask if there's a Kubernetes Jobs equivalent in Docker Swarm? So far I couldn't find official documentation on Docker website supporting this feature.
Related
I have a project to containerize several applications (Gitlab, Jenkins, Wordpress, Python Flask app...). Currently each application runs on a Compute Engine VM each at GCP. My goal would be to move everything to a cluster (Swarm or Kubernetes).
However I have different questions about Docker Swarm on Google Cloud Platform:
How can I expose my Python application on the outside (HTTP load balancer) as well as the other applications only available in my private VPC ?
From what I've seen on the internet, I have the impression that docker swarm is very little used. Should I go for a kubernetes cluster instead ? (I have good knowledge of Docker/Kubernetes)
It is difficult to find information about Docker Swarm in cloud providers. What would be an architecture with Docker Swarm on GCP?
Thanks for your help.
I'd create a template and from that an instance group for all VM, which shall host the Docker swarm. And a separate instance or instance group for said internal purposes - so that there is a strict separation, which can then be used to route the internal & external traffic accordingly (this would apply in any case). Google Kubernetes Engine is about the same as such an instance group, but Google managed infrastructure. See the tutorial, there's not much difference - except that it better integrates with gcloud & kubectl. While there is no requirement to want or need to maintain the underlying infrastructure, GKE is probably less effort.
What you are basically asking is:
Kubernetes vs. Docker Swarm: What’s the Difference?
Docker Swarm vs Kubernetes: A Helpful Guide for Picking One
Kubernetes vs. Docker: What Does it Really Mean?
Docker Swarm vs. Kubernetes: A Comparison
Kubernetes vs Docker Swarm
I have a few tasks running in containers, which works as usual, and just stacks. Now I want to add a few machines, for the same tasks. What I'm trying to achieve, it's some kind of Executors and active node pool, where all other tasks queue up.
What I have tried so far, it's just single Docker Container of Jenkins, where we can add new worker machines, and execute usual tasks. Where Jenkins will manage load balancing during work. Nothing special here.
We also have Docker Swarm, for Container Orchestration, which in my understanding, should do the same - Manage Containers (and tasks). And from the Documentation, there is only one task for the Swarm it's managing scale and load balancing on the Server(by splitting traffic between working nodes).
1) Is it possible (and how) to create Docker Swarm cluster as Executor of the active machine, and submit other Containers(a task) to it, so Swarm will manage on which node should it start execution. If no, what is the right solution for such a task (container task submission)?
2) What is the other(maybe few of them) purposes of Docker Swarm, besides managing scale and load balancing (describing in the Doc)? Because general documentation, has example only for scaling Web Application?
I am new to cluster container management, and this question is the basis for all the freshers over here.
I read some documentation, but still, my understanding is not too clear, so any leads.. helping to understand?
Somewhere it is mentioned, Minikube is used to run Kubernetes locally. So if we want to maintain cluster management in my four-node Raspberry Pi, then Minikube is not the option?
Does Minikube support only a one-node system?
Docker Compose is set of instructions and a YAML file to configure and start multiple Docker containers. Can we use this to start containers of the different hosts? Then for simple orchestration where I need to call container of the second host, I don't need any cluster management, right?
What is the link between Docker Swarm and Kubernetes? Both are independent cluster management. Is it efficient to use Kubernetes on Raspberry Pi? Any issue, because I was told that Kubernetes in single node takes the complete memory and CPU usage? Is it true?
Is there other cluster management for Raspberry Pi?
I think this 4-5 set will help me better.
Presuming that your goal here is to run a set of containers over a number of different Raspberry Pi based nodes:
Minikube isn't really appropriate. This starts a single virtual machine on a Windows, MacOS or Linux and installs a Kubernetes cluster into it. It's generally used by developers to quickly start-up a cluster on their laptops or desktops for development and testing purposes.
Docker Compose is a system for managing sets of related containers. So for example if you had a web server and database that you wanted to manage together you could put them in a single Docker Compose file.
Docker Swarm is a system for managing sets of containers across multiple hosts. It's essentially an alternative to Kubernetes. It has fewer features than Kubernetes, but it is much simpler to set up.
If you want a really simple multi-node Container cluster, I'd say that Docker swarm is a reasonable choice. If you explicitly want to experiment with Kubernetes, I'd say that kubeadm is a good option here. Kubernetes in general has higher resource requirements than Docker Swarm, so it could be somewhat less suited to it, although I know people have successfully run Kubernetes clusters on Raspberry Pis.
Docker Compose
A utility to to start multiple docker containers on a single host using a single docker-compose up. This makes it easier to start multiple containers at once, rather than having do mutliple docker run commands.
Docker swarm
A native container orchestrator for Docker. Docker swarm allows you to create a cluster of docker containers running on multiple machines. It provides features such as replication, scaling, self-healing i.e. starting a new container when one dies ...
Kubernetes
Also a container orchestrator. Kubernetes and Docker swarm can be considered as alternatives to one another. They both try to handle managing containers starting in a cluster
Minikube
Creating a real kubernetes cluster requires having multiple machines either on premise or on a cloud platform. This is not always convenient if someone is just new to Kubernetes and trying to learn by playing around with Kubernetes. To solve that minikube allows you to start a very basic Kubernetes cluster that consists of a single VM on you machine, which you can use to play around with Kubernetes.
Minikube is not for a production or multi-node cluster. There are many tools that can be used to create a multi-node Kubernetes cluster such as kubeadm
Containers are the future of application deployment. Containers are smallest unit of deployment in docker. There are three components in docker as docker engine to run a single container, docker-compose to run a multi-container application on a single host and docker-swarm to run multi-container application across hosts which also an orchestration tool.
In kubernetes, the smallest unit of deployment is Pod(which is composed of multiple container). Minikube is a single node cluster where you can install it locally and try, test and feel the kubernetes features locally. But, you can't scale this to more than a single machine. Kubernetes is an orchestration tool like Docker Swarm but more prominent than Docker Swarm with respect to features, scaling, resiliency, and security.
You can do the analysis and think about which tool will be fit for your requirements. Each one having their own pros or cons like docker swarm is good and easy to manage small clusters whereas kubernetes is much better for larger once. There is another orchestration tool Mesos which is also popular and used in largest size clusters.
Check this out, Choose your own Adventure but, it's just a general analogy and only to understand because all the three technologies are evolving rapidly.
I get the impression you're mostly looking for confirmation and am happy to help with that if I can.
Yes, minikube is local-only
Yes, minikube is intended to be single-node
Docker-compose isn't really an orchestration system like swarm and Kubernetes are. It helps with running related containers on a single host, but it is not used for multi-host.
Kubernetes and Docker Swarm are both container orchestration systems. These systems are good at managing scaling up, but they have an overhead associated with them so they're better suited to multi-node.
I don't know the range of orchestration options for Raspberry Pi, but there are Kubernetes examples out there such as Build Your Own Cloud with Kubernetes and Some Raspberry Pi.
For Pi, you can use Docker Swarm Mode on one or more Pi's. You can even run ARM emulation for testing on Docker for Windows/Mac before trying to get it all working directly on a Pi. Same goes for Kubernetes, as it's built-in to Docker for Windows/Mac now (no minikube needed).
Alex Ellis has a good blog on Pi and Docker and this post may help too.
I've been playing around with orchestrating Docker containers on a subnet of Raspberry Pis (3Bs).
I found Docker-swarm easiest to set up and work with, and adequate for my purposes. Guide: https://docs.docker.com/engine/swarm/swarm-tutorial/
For Kubernetes there are two main options; k3s and microk8s. Some guides:
k3s
https://bryanbende.com/development/2021/05/07/k3s-raspberry-pi-initial-setup
microk8s
https://ubuntu.com/tutorials/how-to-kubernetes-cluster-on-raspberry-pi#1-overview
I know that Docker and Kubernetes aren’t direct competitors. Docker is the container platform and containers are coordinated and scheduled by Kubernetes, which is a tool.
What does it really mean and how can I deploy my app on Docker for Azure ?
Short answer:
Docker (and containers in general) solve the problem of packaging an application and its dependencies. This makes it easy to ship and run everywhere.
Kubernetes is one layer of abstraction above containers. It is a distributed system that controls/manages containers.
My advice: because the landscape is huge... start learning and putting the pieces of the puzzle together by following a course. Below I have added some information from the:
Introduction to Kubernetes, free online course from The Linux Foundation.
Why do we need Kubernetes (and other orchestrators) above containers?
In the quality assurance (QA) environments, we can get away with running containers on a single host to develop and test applications. However, when we go to production, we do not have the same liberty, as we need to ensure that our applications:
Are fault-tolerant
Can scale, and do this on-demand
Use resources optimally
Can discover other applications automatically, and communicate with each other
Are accessible from the external world
Can update/rollback without any downtime.
Container orchestrators are the tools which group hosts together to form a cluster, and help us fulfill the requirements mentioned above.
Nowadays, there are many container orchestrators available, such as:
Docker Swarm: Docker Swarm is a container orchestrator provided by Docker, Inc. It is part of Docker Engine.
Kubernetes: Kubernetes was started by Google, but now, it is a part of the Cloud Native Computing Foundation project.
Mesos Marathon: Marathon is one of the frameworks to run containers at scale on Apache Mesos.
Amazon ECS: Amazon EC2 Container Service (ECS) is a hosted service provided by AWS to run Docker containers at scale on its infrastructrue.
Hashicorp Nomad: Nomad is the container orchestrator provided by HashiCorp.
Kubernetes is built on Docker technology. It is an orchestration tool for Docker container whereas Docker is a technology to create and deploy containers.
Docker, starting with a platform-as-a-service (PaaS) provider named dotCloud.
All in all, Kubernetes is related to the Docker container, allowing you to implement application portability and extensibility in container orchestration.
DOCKER
Easy and fast to install and configure
Functionality is provided and limited by the Docker API
Quick container deployment and scaling even in very large clusters
Automated internal load balancing through any node in the cluster
Simple shared local volumes
Kubernetes
Require some work to get up and running
Client, API and YAML definitions are unique to Kubernetes
Provides strong guarantees to cluster states at the expense of speed
To Enable load balancing requires manual service configuration
Volumes shared within pods
This is just a basic idea which at least explains the difference.If you want to go in depth see my posts
http://www.thecreativedev.com/an-introduction-to-kubernetes/
http://www.thecreativedev.com/learn-docker-works/
Docker and Kubernetes are complementary. Docker provides an open standard for packaging and distributing containerized applications, while Kubernetes provides for the orchestration and management of distributed, containerized applications created with Docker. In other words, Kubernetes provides the infrastructure needed to deploy and run applications built with Docker.
I have some tasks defined as Docker containers, each one will consume one full CPU whilst it runs.
Id like to run them as cost efficiently as possible so that VMs are only active when the tasks are running.
Whats the best way to do this on Google Cloud Platform?
It seems Kuberenetes and other cluster managers assume you will be running some service, and have spare capacity in your cluster to schedule the containers.
Is there any program or system that I can use to define my tasks, and then start/stop VMs on a schedule to run those tasks?
I think the best way is to just use the GCP/Docker APIs and script it myself?
You're right, all the major cloud container services provide you a cluster for running containers - GCP Container Engine, EC2 Container Service, and Azure Container Service.
In all those cases, the compute is charged by the VMs in the cluster, so you'll pay while the VMs are running. If you have an occasional workload you'll need to script creating or starting the VMs before running your containers, and stopping or deleting them when you're done.
An exception is Joyent's cloud, which let's you run Docker containers and charges per container - that could fit your scenario.
Disclaimer - I don't work for Google, Amazon, Microsoft or Joyent. Or Samsung.