I need to monitor OpenVZ containers using TICK stack. But it must be done without install anything inside of containers. Is there any plugins for Telegraf to collect metric (cpu, bandwidth, iops) from OpenVZ container?
OpenVZ is deprecated since long time. Try this new thing named Docker, or at least LXC.
Telegraf uses cgroups for collecting metrics from containers, Docker, LXC use cgroups.
Related
I am planning to use cAdvisor to monitor performance of running docker container on multiple VMs, do I need to install cAdvisor on all VMs, or there is any other way?
Yes, you need it on each host seeing as it uses the local mounts to get the data it exports
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
Does Marathon impose a disk space resource limit on Docker container applications? By default, I know that Docker containers can grow as needed in their host VMs, but when I tried to have Marathon and Mesos create and manage my Docker containers, I found that the container would run out of space during installation of packages. As it stands, I cannot just cache the installation of these packages in a prebuilt image.
So if Marathon does impose a disk space resource limit, is there a way to turn that off?
Marathon should not impose a size limit on your containers, and as far as I am aware there are no limitations to the size of a container that Marathon can run, so long as the box you are running Marathon and the containers on top of have sufficient resources allocated (remaining).
That being said, there is a great response by user mbarthelemy at this link where he goes into detail regarding devicemapper settings in Ubuntu that allow you to allocate disk size and network resources to each container on a docker level.
No. Marathon does not enforce any resource limits itself, although your app definition can declare cpu/memory/disk limits. It is up to Mesos to actually enforce these limits. Mesos 0.22 added support for disk quota isolation, but it is not enabled by default (check the slave's --isolators flag), so I doubt that was your problem.
What is the slave's --work_dir? If it's mapping to /tmp/mesos (default), and that happens to be a tiny ramdisk/SSD, you might actually be running out of space on the host machine/VM.
Questions
How does lxd provide Full operating system functionality within containers, not just single processes?
How is it different from lxc/docker + wrappers?
Is it similar to a container that is launched with docker + supervisor/wrapper script to contain multiple processes in one container?
In other words:
What can I do with lxd that I cannot do with some wrappers over lxc and docker ?
Why is it available only in ubuntu if they are making use of mainline kernel features (namespaces and cgroup )?
How does lxd provide Full operating system functionality within containers, not just single processes?
Containers are Isolated Linux systems using the cgroups capabilities for limit cpu/memory/network/etc in the Linux kernel, without the need for starting a full virtual machine.
LXD uses the capabilities provided by liblxc (that is based in LXC) and from this comes the capabilities for full OS functionality.
How is it different from lxc/docker + wrappers?
LXD use liblxc from LXC. Docker is more application focused, only the principal process for your app inside the container (using libcontainer now by default, Docker did use liblxc first for this)
Is it similar to a container that is launched with docker + supervisor/wrapper
script to contain multiple processes in one container?
Something similar. The diference between LXD and Docker is that Docker is an application container, LXD is a system container. LXD use upstart/systemd like principal process inside the container and by default is ready to be a full VM environment with very light memory/cpu usage. Yes, you can build your docker with supervisorctl/runit, but you need to do manually this process. You can check how is done in http://phusion.github.io/baseimage-docker/ that do something similar inside a container.
What can I do with lxd that I cannot do with some wrappers over lxc and docker ?
live migrations of containers, use your containers like full virtual machines, precise config for dedicate cpu cores/memory/network I/O for use in your container, run your container process in unprivileged mode (root process inside your container != root process in your host) by default Docker work in privileged mode, only now in Docker 1.10 they implement unprivileged mode but you need to review (and maybe rewrite) your Dockerfiles because many things will not work in unprivileged mode.
LXD and Docker are diferent things. LXD gives you a "full OS" in a container and you can use any deployment tool that works in a VM for deploying applications in LXD. With Docker your application is inside the container and you need diferent tools for deploying applications in Docker and do metric for performance. Docker is designed to run on various OS platforms, like Windows. LXD/LXC can only run on Linux: this is the reason Docker no longer uses LXC as part of its stack.
Why is it available only in ubuntu if they are making use of mainline kernel features (namespaces and cgroup )?
LXD has commercial support from Canonical if is needed, but you can build LXD in Centos 7, ArchLinux (with kernel patched) check https://github.com/lxc/lxd. Gentoo supports LXD now https://wiki.gentoo.org/wiki/LXD.
LXD is based on liblxc, its purpose is to control some lxc with added capabilities, like snapshots or live migration. LXD is linked to LXC and they are OS centered.
Docker is much more application centered, based at the beginning on LXC but now independent from LXC, it can use openvz or whatever. Docker only focuses on application with lib and dependency, not on OS.
look at this for more :
https://www.flockport.com/lxc-vs-lxd-vs-docker-making-sense-of-the-rapidly-evolving-container-ecosystem/
Regards.
LXD works in conjunction with LXC and is not designed to replace or supplant LXC. Instead, it’s intended to make LXC-based containers easier to use through the addition of a back-end daemon supporting a REST API and a straightforward CLI client that works with both the local daemon and remote daemons via the REST API.
LXD is more like docker host.
My understanding of Linux Containers (LXC) is that it provides a native hypervisor for Linux systems, similar to Windows' Hyper-V introduced in Windows 8. By "native hypervisor", I mean, the ability for the Linux system to host guest VMs inside of it without having to install any kind of specialized virtualization software.
My understanding of Docker is that it somehow builds on top of LXC, and allows application developers to define:
The exact app stack of a VM/node, including the OS, the exact configuration and tuning of the OS, and any tools or applications installed/configured/deployed to that OS; and
The exact resource requirements for running this VM/node, including CPU requirements, memory/disk/network requirements, load balancing and replication requirements, etc. Docker then figures out what nodes to run the container on, using these declared requirements as its baseline.
So first off, if my understanding of LXC or Docker is mislead at all, please begin by correcting me!
Assuming I'm more or less correct in my understanding, I ask:
What is the relationship between Docker and, say, vmWare or Xen VMs? Does Docker "sit on top" of the virtualization layer? In other words, are there "Docker bindings" for different virtualization platforms (vmWare, Xen, kvm, etc.), and I could take a Docker container for myapp and deploy it to any Docker-ified platform?
What is the relationship between LXC and Docker? Does Docker simply just extend LXC, or is it a similar (but completely separate) concept altogether? If its an extension of LXC, then in what way?
relationship between LXC and Docker, -> docker started using LXC, but since docker 0.9, docker uses libcontainer, and no longer uses lxc-start to start the containers. Compared to LXC, docker offers a REST Api, allows to move images from and to the registry, allows to build using Dockerfiles...