Mesos now supports Docker. If I run Docker as an Executor, do I still get some of the high-availability and scheduling benefits of Mesos? Or do I have to run Docker tasks e.g. within Marathon to get this?
What would be the benefit of using Mesos + (native) Docker instead of just plain Docker without Mesos? I understand the idea of using Mesos + Marathon + Docker tasks because I get the HA and failover benefits.
Mesos natively supports Docker images as executors within your framework. The benefit of this is that you can now deploy a docker container without having to be aware of the internal topology of your server cluster. With just Docker, you have to connect to the exact remote host and do system-specific configuration.
As for HA, you will need to use a meta-framework (like Marathon, Docker Swarm, etc) in order to monitor your instances and configure redundancy and fault-tolerance. With Marathon this is trivially easy, and works by default.
Related
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
Pretty basic question. We have an existing swarm and I want to start migrating to Kubernetes. Can I run both using the same docker hosts?
See the official documentation for Docker for Mac at https://docs.docker.com/docker-for-mac/kubernetes/ stating:
When Kubernetes support is enabled, you can deploy your workloads, in parallel, on Kubernetes, Swarm, and as standalone containers. Enabling or disabling the Kubernetes server does not affect your other workloads.
So: yes, both should be able to run in parallel.
If you're using Docker on Linux you won't have the convenient tools available like in Docker for Mac/Windows, but both orchestrators should still be able to run in parallel without further issues. On system level, details like e.g. ports on a network interface are still shared resources, so they cannot be bound by different orchestrators.
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 had been having great success so far using Mesos, Marathon, and Docker to manage a fleet of servers, and the containers I'm placing on them.
However, due to some problems I had to destroy my MesosMaster machine and now when I started the machine again and connected it with zookeeper cluster, I dont see anymore docker containers on marathon.
Those docker containers are running since they run on MesosSlaves and I can see them running when I ssh into those slave servers. But they no longer appear on Marathon GUI.
Now I can go back and start all the containers again on marathon GUI manually(takes alot of time) but I think that there has to be another smarter way to it.
Can somebody help me out here because my understanding of the logic of mesos, zookeeper tells me that my above actions should not have implications and mesos cluster should be smart enough to see the docker containers.
We are using Jenkins and docker for doing CI/CD. Our Jenkins is setup as master/slave style, where slaves are distributed across different data centers. when a new build needs to happen Jenkins master identifies a slave in one of the DC and spin up a ephemeral container and tear it down once done.
Due to firewall limitations, we only have about 10 ports open for the slaves in some of the DCs. for example Port Range: 8000 - 8010. In general docker uses the linux port ranges 32768 to 61000. The problem is Jenkins master can not talk to the containers if the host port is bound out of 8000 - 8010. Jenkins docker plugin has limitation where you can not bind multiple ports (may be I am wrong here). I would like to know if any way we can configure this at docker end or in Jenkins docker plugin.
After researching in many forums and talking to people, this is not possible or recommended even to try doing. The recommended implementation to overcome this issue is to move to Docker Swarm,
where you have only one virtual docker cloud
which takes care of spinning up containers behind the scenes and keep it ready for consumption even before the need arises. The configurations options are flexible.
Read more about Swarm here
https://docs.docker.com/swarm/