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張 旭

你到底知不知道什麼是 Kubernetes? | Hwchiu Learning Note - 0 views

  • Storage(儲存) 實際上一直都不是一個簡單處理的問題,從軟體面來看實際上牽扯到非常多的層級,譬如 Linux Kernel, FileSystem, Block/File-Level, Cache, Snapshot, Object Storage 等各式各樣的議題可以討論。
  • DRBD
  • 異地備援,容錯機制,快照,重複資料刪除等超多相關的議題基本上從來沒有一個完美的解法能夠滿足所有使用情境。
  • ...20 more annotations...
  • 管理者可能會直接在 NFS Server 上進行 MDADM 來設定相關的 Block Device 並且基於上面提供 Export 供 NFS 使用,甚至底層套用不同的檔案系統 (EXT4/BTF4) 來獲取不同的功能與效能。
  • Kubernetes 就只是 NFS Client 的角色
  • CSI(Container Storage Interface)。CSI 本身作為 Kubernetes 與 Storage Solution 的中介層。
  • 基本上 Pod 裡面每個 Container 會使用 Volume 這個物件來代表容器內的掛載點,而在外部實際上會透過 PVC 以及 PV 的方式來描述這個 Volume 背後的儲存方案伺服器的資訊。
  • 整體會透過 CSI 的元件們與最外面實際上的儲存設備連接,所有儲存相關的功能是否有實現,有支援全部都要仰賴最後面的實際提供者, kubernetes 只透過 CSI 的標準去執行。
  • 在網路部分也有與之對應的 CNI(Container Network Interface). kubernetes 透過 CNI 這個介面來與後方的 網路解決方案 溝通
  • CNI 最基本的要求就是在在對應的階段為對應的容器提供網路能力
  • 目前最常見也是 IPv4 + TCP/UDP 的傳輸方式,因此才會看到大部分的 CNI 都在講這些。
  • 希望所有容器彼此之間可以透過 IPv4 來互相存取彼此,不論是同節點或是跨節點的容器們都要可以滿足這個需求。
  • 容器間到底怎麼傳輸的,需不需要封裝,透過什麼網卡,要不要透過 NAT 處理? 這一切都是 CNI 介面背後的實現
  • 外部網路存取容器服務 (Service/Ingress)
  • kubernetes 在 Service/Ingress 中間自行實現了一個模組,大抵上稱為 kube-proxy, 其底層可以使用 iptables, IPVS, user-space software 等不同的實現方法,這部分是跟 CNI 完全無關。
  • CNI 跟 Service/Ingress 是會衝突的,也有可能彼此沒有配合,這中間沒有絕對的穩定整合。
  • CNI 一般會處理的部份,包含了容器內的 網卡數量,網卡名稱,網卡IP, 以及容器與外部節點的連接能力等
  • CRI (Container Runtime Interface) 或是 Device Plugin
  • 對於 kubernetes 來說,其實本身並不在意到底底下的容器化技術實際上是怎麼實現的,你要用 Docker, rkt, CRI-O 都無所謂,甚至背後是一個偽裝成 Container 的 Virtaul Machine virtlet 都可以。
  • 去思考到底為什麼自己本身的服務需要容器化,容器化可以帶來什麼優點
  • 太多太多的人都認為只要寫一個 Dockerfile 將原先的應用程式們全部包裝起來放在一起就是一個很好的容器 來使用了。
  • 最後就會發現根本把 Container 當作 Virtual Machine 來使用,然後再補一句 Contaienr 根本不好用啊
  • 容器化 不是把直接 Virtual Machine 的使用習慣換個環境使用就叫做 容器化,而是要從概念上去暸解與使用
張 旭

MetalLB, bare metal load-balancer for Kubernetes - 0 views

  • it allows you to create Kubernetes services of type “LoadBalancer” in clusters that don’t run on a cloud provider
  • In a cloud-enabled Kubernetes cluster, you request a load-balancer, and your cloud platform assigns an IP address to you.
  • MetalLB cannot create IP addresses out of thin air, so you do have to give it pools of IP addresses that it can use.
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  • MetalLB lets you define as many address pools as you want, and doesn’t care what “kind” of addresses you give it.
  • Once MetalLB has assigned an external IP address to a service, it needs to make the network beyond the cluster aware that the IP “lives” in the cluster.
  • In layer 2 mode, one machine in the cluster takes ownership of the service, and uses standard address discovery protocols (ARP for IPv4, NDP for IPv6) to make those IPs reachable on the local network
  • From the LAN’s point of view, the announcing machine simply has multiple IP addresses.
  • In BGP mode, all machines in the cluster establish BGP peering sessions with nearby routers that you control, and tell those routers how to forward traffic to the service IPs.
  • Using BGP allows for true load balancing across multiple nodes, and fine-grained traffic control thanks to BGP’s policy mechanisms.
張 旭

LXC vs Docker: Why Docker is Better | UpGuard - 0 views

  • LXC (LinuX Containers) is a OS-level virtualization technology that allows creation and running of multiple isolated Linux virtual environments (VE) on a single control host.
  • Docker, previously called dotCloud, was started as a side project and only open-sourced in 2013. It is really an extension of LXC’s capabilities.
  • run processes in isolation.
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  • Docker is developed in the Go language and utilizes LXC, cgroups, and the Linux kernel itself. Since it’s based on LXC, a Docker container does not include a separate operating system; instead it relies on the operating system’s own functionality as provided by the underlying infrastructure.
  • Docker acts as a portable container engine, packaging the application and all its dependencies in a virtual container that can run on any Linux server.
  • a VE there is no preloaded emulation manager software as in a VM.
  • In a VE, the application (or OS) is spawned in a container and runs with no added overhead, except for a usually minuscule VE initialization process.
  • LXC will boast bare metal performance characteristics because it only packages the needed applications.
  • the OS is also just another application that can be packaged too.
  • a VM, which packages the entire OS and machine setup, including hard drive, virtual processors and network interfaces. The resulting bloated mass usually takes a long time to boot and consumes a lot of CPU and RAM.
  • don’t offer some other neat features of VM’s such as IaaS setups and live migration.
  • LXC as supercharged chroot on Linux. It allows you to not only isolate applications, but even the entire OS.
  • Libvirt, which allows the use of containers through the LXC driver by connecting to 'lxc:///'.
  • 'LXC', is not compatible with libvirt, but is more flexible with more userspace tools.
  • Portable deployment across machines
  • Versioning: Docker includes git-like capabilities for tracking successive versions of a container
  • Component reuse: Docker allows building or stacking of already created packages.
  • Shared libraries: There is already a public registry (http://index.docker.io/ ) where thousands have already uploaded the useful containers they have created.
  • Docker taking the devops world by storm since its launch back in 2013.
  • LXC, while older, has not been as popular with developers as Docker has proven to be
  • LXC having a focus on sys admins that’s similar to what solutions like the Solaris operating system, with its Solaris Zones, Linux OpenVZ, and FreeBSD, with its BSD Jails virtualization system
  • it started out being built on top of LXC, Docker later moved beyond LXC containers to its own execution environment called libcontainer.
  • Unlike LXC, which launches an operating system init for each container, Docker provides one OS environment, supplied by the Docker Engine
  • LXC tooling sticks close to what system administrators running bare metal servers are used to
  • The LXC command line provides essential commands that cover routine management tasks, including the creation, launch, and deletion of LXC containers.
  • Docker containers aim to be even lighter weight in order to support the fast, highly scalable, deployment of applications with microservice architecture.
  • With backing from Canonical, LXC and LXD have an ecosystem tightly bound to the rest of the open source Linux community.
  • Docker Swarm
  • Docker Trusted Registry
  • Docker Compose
  • Docker Machine
  • Kubernetes facilitates the deployment of containers in your data center by representing a cluster of servers as a single system.
  • Swarm is Docker’s clustering, scheduling and orchestration tool for managing a cluster of Docker hosts. 
  • rkt is a security minded container engine that uses KVM for VM-based isolation and packs other enhanced security features. 
  • Apache Mesos can run different kinds of distributed jobs, including containers. 
  • Elastic Container Service is Amazon’s service for running and orchestrating containerized applications on AWS
  • LXC offers the advantages of a VE on Linux, mainly the ability to isolate your own private workloads from one another. It is a cheaper and faster solution to implement than a VM, but doing so requires a bit of extra learning and expertise.
  • Docker is a significant improvement of LXC’s capabilities.
張 旭

What is Kubernetes Ingress? | IBM - 0 views

  • expose an application to the outside of your Kubernetes cluster,
  • ClusterIP, NodePort, LoadBalancer, and Ingress.
  • A service is essentially a frontend for your application that automatically reroutes traffic to available pods in an evenly distributed way.
  • ...23 more annotations...
  • Services are an abstract way of exposing an application running on a set of pods as a network service.
  • Pods are immutable, which means that when they die, they are not resurrected. The Kubernetes cluster creates new pods in the same node or in a new node once a pod dies. 
  • A service provides a single point of access from outside the Kubernetes cluster and allows you to dynamically access a group of replica pods. 
  • For internal application access within a Kubernetes cluster, ClusterIP is the preferred method
  • To expose a service to external network requests, NodePort, LoadBalancer, and Ingress are possible options.
  • Kubernetes Ingress is an API object that provides routing rules to manage external users' access to the services in a Kubernetes cluster, typically via HTTPS/HTTP.
  • content-based routing, support for multiple protocols, and authentication.
  • Ingress is made up of an Ingress API object and the Ingress Controller.
  • Kubernetes Ingress is an API object that describes the desired state for exposing services to the outside of the Kubernetes cluster.
  • An Ingress Controller reads and processes the Ingress Resource information and usually runs as pods within the Kubernetes cluster.  
  • If Kubernetes Ingress is the API object that provides routing rules to manage external access to services, Ingress Controller is the actual implementation of the Ingress API.
  • The Ingress Controller is usually a load balancer for routing external traffic to your Kubernetes cluster and is responsible for L4-L7 Network Services. 
  • Layer 7 (L7) refers to the application level of the OSI stack—external connections load-balanced across pods, based on requests.
  • if Kubernetes Ingress is a computer, then Ingress Controller is a programmer using the computer and taking action.
  • Ingress Rules are a set of rules for processing inbound HTTP traffic. An Ingress with no rules sends all traffic to a single default backend service. 
  • the Ingress Controller is an application that runs in a Kubernetes cluster and configures an HTTP load balancer according to Ingress Resources.
  • The load balancer can be a software load balancer running in the cluster or a hardware or cloud load balancer running externally.
  • ClusterIP is the preferred option for internal service access and uses an internal IP address to access the service
  • A NodePort is a virtual machine (VM) used to expose a service on a Static Port number.
  • a NodePort would be used to expose a single service (with no load-balancing requirements for multiple services).
  • Ingress enables you to consolidate the traffic-routing rules into a single resource and runs as part of a Kubernetes cluster.
  • An application is accessed from the Internet via Port 80 (HTTP) or Port 443 (HTTPS), and Ingress is an object that allows access to your Kubernetes services from outside the Kubernetes cluster. 
  • To implement Ingress, you need to configure an Ingress Controller in your cluster—it is responsible for processing Ingress Resource information and allowing traffic based on the Ingress Rules.
張 旭

Run your CI/CD jobs in Docker containers | GitLab - 0 views

  • If you run Docker on your local machine, you can run tests in the container, rather than testing on a dedicated CI/CD server.
  • Run other services, like MySQL, in containers. Do this by specifying services in your .gitlab-ci.yml file.
  • By default, the executor pulls images from Docker Hub
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  • Maps must contain at least the name option, which is the same image name as used for the string setting.
  • When a CI job runs in a Docker container, the before_script, script, and after_script commands run in the /builds/<project-path>/ directory. Your image may have a different default WORKDIR defined. To move to your WORKDIR, save the WORKDIR as an environment variable so you can reference it in the container during the job’s runtime.
  • The runner starts a Docker container using the defined entrypoint. The default from Dockerfile that may be overridden in the .gitlab-ci.yml file.
  • attaches itself to a running container.
  • sends the script to the container’s shell stdin and receives the output.
  • To override the entrypoint of a Docker image, define an empty entrypoint in the .gitlab-ci.yml file, so the runner does not start a useless shell layer. However, that does not work for all Docker versions. For Docker 17.06 and later, the entrypoint can be set to an empty value. For Docker 17.03 and earlier, the entrypoint can be set to /bin/sh -c, /bin/bash -c, or an equivalent shell available in the image.
  • The runner expects that the image has no entrypoint or that the entrypoint is prepared to start a shell command.
  • entrypoint: [""]
  • entrypoint: ["/bin/sh", "-c"]
  • A DOCKER_AUTH_CONFIG CI/CD variable
  •  
    "If you run Docker on your local machine, you can run tests in the container, rather than testing on a dedicated CI/CD server. "
張 旭

Cluster Networking - Kubernetes - 0 views

  • Networking is a central part of Kubernetes, but it can be challenging to understand exactly how it is expected to work
  • Highly-coupled container-to-container communications
  • Pod-to-Pod communications
  • ...57 more annotations...
  • this is the primary focus of this document
    • 張 旭
       
      Cluster Networking 所關注處理的是: Pod 到 Pod 之間的連線
  • Pod-to-Service communications
  • External-to-Service communications
  • Kubernetes is all about sharing machines between applications.
  • sharing machines requires ensuring that two applications do not try to use the same ports.
  • Dynamic port allocation brings a lot of complications to the system
  • Every Pod gets its own IP address
  • do not need to explicitly create links between Pods
  • almost never need to deal with mapping container ports to host ports.
  • Pods can be treated much like VMs or physical hosts from the perspectives of port allocation, naming, service discovery, load balancing, application configuration, and migration.
  • pods on a node can communicate with all pods on all nodes without NAT
  • agents on a node (e.g. system daemons, kubelet) can communicate with all pods on that node
  • pods in the host network of a node can communicate with all pods on all nodes without NAT
  • If your job previously ran in a VM, your VM had an IP and could talk to other VMs in your project. This is the same basic model.
  • containers within a Pod share their network namespaces - including their IP address
  • containers within a Pod can all reach each other’s ports on localhost
  • containers within a Pod must coordinate port usage
  • “IP-per-pod” model.
  • request ports on the Node itself which forward to your Pod (called host ports), but this is a very niche operation
  • The Pod itself is blind to the existence or non-existence of host ports.
  • AOS is an Intent-Based Networking system that creates and manages complex datacenter environments from a simple integrated platform.
  • Cisco Application Centric Infrastructure offers an integrated overlay and underlay SDN solution that supports containers, virtual machines, and bare metal servers.
  • AOS Reference Design currently supports Layer-3 connected hosts that eliminate legacy Layer-2 switching problems.
  • The AWS VPC CNI offers integrated AWS Virtual Private Cloud (VPC) networking for Kubernetes clusters.
  • users can apply existing AWS VPC networking and security best practices for building Kubernetes clusters.
  • Using this CNI plugin allows Kubernetes pods to have the same IP address inside the pod as they do on the VPC network.
  • The CNI allocates AWS Elastic Networking Interfaces (ENIs) to each Kubernetes node and using the secondary IP range from each ENI for pods on the node.
  • Big Cloud Fabric is a cloud native networking architecture, designed to run Kubernetes in private cloud/on-premises environments.
  • Cilium is L7/HTTP aware and can enforce network policies on L3-L7 using an identity based security model that is decoupled from network addressing.
  • CNI-Genie is a CNI plugin that enables Kubernetes to simultaneously have access to different implementations of the Kubernetes network model in runtime.
  • CNI-Genie also supports assigning multiple IP addresses to a pod, each from a different CNI plugin.
  • cni-ipvlan-vpc-k8s contains a set of CNI and IPAM plugins to provide a simple, host-local, low latency, high throughput, and compliant networking stack for Kubernetes within Amazon Virtual Private Cloud (VPC) environments by making use of Amazon Elastic Network Interfaces (ENI) and binding AWS-managed IPs into Pods using the Linux kernel’s IPvlan driver in L2 mode.
  • to be straightforward to configure and deploy within a VPC
  • Contiv provides configurable networking
  • Contrail, based on Tungsten Fabric, is a truly open, multi-cloud network virtualization and policy management platform.
  • DANM is a networking solution for telco workloads running in a Kubernetes cluster.
  • Flannel is a very simple overlay network that satisfies the Kubernetes requirements.
  • Any traffic bound for that subnet will be routed directly to the VM by the GCE network fabric.
  • sysctl net.ipv4.ip_forward=1
  • Jaguar provides overlay network using vxlan and Jaguar CNIPlugin provides one IP address per pod.
  • Knitter is a network solution which supports multiple networking in Kubernetes.
  • Kube-OVN is an OVN-based kubernetes network fabric for enterprises.
  • Kube-router provides a Linux LVS/IPVS-based service proxy, a Linux kernel forwarding-based pod-to-pod networking solution with no overlays, and iptables/ipset-based network policy enforcer.
  • If you have a “dumb” L2 network, such as a simple switch in a “bare-metal” environment, you should be able to do something similar to the above GCE setup.
  • Multus is a Multi CNI plugin to support the Multi Networking feature in Kubernetes using CRD based network objects in Kubernetes.
  • NSX-T can provide network virtualization for a multi-cloud and multi-hypervisor environment and is focused on emerging application frameworks and architectures that have heterogeneous endpoints and technology stacks.
  • NSX-T Container Plug-in (NCP) provides integration between NSX-T and container orchestrators such as Kubernetes
  • Nuage uses the open source Open vSwitch for the data plane along with a feature rich SDN Controller built on open standards.
  • OpenVSwitch is a somewhat more mature but also complicated way to build an overlay network
  • OVN is an opensource network virtualization solution developed by the Open vSwitch community.
  • Project Calico is an open source container networking provider and network policy engine.
  • Calico provides a highly scalable networking and network policy solution for connecting Kubernetes pods based on the same IP networking principles as the internet
  • Calico can be deployed without encapsulation or overlays to provide high-performance, high-scale data center networking.
  • Calico can also be run in policy enforcement mode in conjunction with other networking solutions such as Flannel, aka canal, or native GCE, AWS or Azure networking.
  • Romana is an open source network and security automation solution that lets you deploy Kubernetes without an overlay network
  • Weave Net runs as a CNI plug-in or stand-alone. In either version, it doesn’t require any configuration or extra code to run, and in both cases, the network provides one IP address per pod - as is standard for Kubernetes.
  • The network model is implemented by the container runtime on each node.
張 旭

The package-lock.json file - 0 views

  • You don't commit to Git your node_modules folder, which is generally huge, and when you try to replicate the project on another machine by using the npm install command,
  • Even if a patch or minor release should not introduce breaking changes
  • The package-lock.json sets your currently installed version of each package in stone, and npm will use those exact versions when running npm ci
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  • The package-lock.json file needs to be committed to your Git repository
  •  
    "You don't commit to Git your node_modules folder, which is generally huge, and when you try to replicate the project on another machine by using the npm install command,"
crazylion lee

Eve - 0 views

  •  
    "Eve is a programming language and IDE based on years of research into building a human-first programming platform. From code embedded in documents to a language without order, it presents an alternative take on what programming could be - one that focuses on us instead of the machine. This is Eve:"
crazylion lee

Image Kernels explained visually - 0 views

  •  
    "An image kernel is a small matrix used to apply effects like the ones you might find in Photoshop or Gimp, such as blurring, sharpening, outlining or embossing. They're also used in machine learning for 'feature extraction', a technique for determining the most important portions of an image. In this context the process is referred to more generally as "convolution" (see: convolutional neural networks.)"
crazylion lee

A.I. Experiments - 0 views

  •  
    " Explore machine learning by playing with pictures, language, music, code, and more."
crazylion lee

htop explained | peteris.rocks - 0 views

  •  
    "For the longest time I did not know what everything meant in htop. I thought that load average 1.0 on my two core machine means that the CPU usage is at 50%. That's not quite right. And also, why does it say 1.0? I decided to look everything up and document it here. They also say that the best way to learn something is to try to teach it. "
crazylion lee

Deep Learning - 0 views

  •  
    "The Deep Learning textbook is a resource intended to help students and practitioners enter the field of machine learning in general and deep learning in particular. The online version of the book is now complete and will remain available online for free. The deep learning textbook can now be pre-ordered on Amazon. Pre-orders should ship on December 16, 2016. For up to date announcements, join our mailing list."
crazylion lee

Proxmox VE - 0 views

  •  
    " Proxmox Virtual Environment is an open source server virtualization management solution based on QEMU/KVM and LXC. You can manage virtual machines, containers, highly available clusters, storage and networks with an integrated, easy-to-use web interface or via CLI. Proxmox VE code is licensed under the GNU Affero General Public License, version 3. The project is developed and maintained by Proxmox Server Solutions GmbH."
crazylion lee

mapmeld/fortran-machine: Testing a Fortran MVC web platform - 0 views

  •  
    "Testing a Fortran MVC web platform https://fortran.io"
crazylion lee

Hjson, a user interface for JSON - 0 views

shared by crazylion lee on 04 Apr 17 - No Cached
  •  
    "JSON is easy for humans to read and write... in theory. In practice JSON gives us plenty of opportunities to make mistakes without even realizing it. Hjson is a syntax extension to JSON. It's NOT a proposal to replace JSON or to incorporate it into the JSON spec itself. It's intended to be used like a user interface for humans, to read and edit before passing the JSON data to the machine."
crazylion lee

Packer - 0 views

  •  
    Packer is a tool for creating identical machine images for multiple platforms from a single source configuration.
張 旭

Getting Started with Docker - Servers for Hackers - 0 views

  • Docker is an isolated portion of the host computer, sharing the host kernel (OS) and even its bin/libraries if appropriate.
  • the Docker Container contains the parts that make Ubuntu different from CoreOS.
  • A Docker container only stays alive as long as there is an active process being run in it.
  • ...10 more annotations...
  • Allocate a (pseudo) tty
  • Keep stdin open (so we can interact with it)
  • Docker allows us make changes to an image, commit those changes, and then push those changes out somehwere.
  • Docker tracks any changes we make to a container
  • The Dockerfile provides a set of instructions for Docker to run on a container.
  • what image (and tag in this case) to base this off of
  • run the given command (as user "root")
  • copy a file from the host machine into the container
  • expose a port to the host machine. You can expose multiple ports
  • run a command
crazylion lee

Keepalived for Linux - 0 views

  •  
    Keepalived is a routing software written in C. The main goal of this project is to provide simple and robust facilities for loadbalancing and high-availability to Linux system and Linux based infrastructures. Loadbalancing framework relies on well-known and widely used Linux Virtual Server (IPVS) kernel module providing Layer4 loadbalancing. Keepalived implements a set of checkers to dynamically and adaptively maintain and manage loadbalanced server pool according their health. On the other hand high-availability is achieved by VRRP protocol. VRRP is a fundamental brick for router failover. In addition, Keepalived implements a set of hooks to the VRRP finite state machine providing low-level and high-speed protocol interactions. Keepalived frameworks can be used independently or all together to provide resilient infrastructures.
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