Dockers and kubernetes
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The document provides an overview of Docker and Kubernetes, emphasizing their roles in building scalable and portable applications. It explains how Docker serves as a shipping container system for software, addressing the complexities of deploying applications across various environments. Additionally, the document highlights the advantages of using Docker containers, such as their lightweight nature, ease of use, and ability to eliminate environment inconsistencies.
Dockers and kubernetes
- 1. Dockers and Kubernetes A way to build scalable and portable applications with Cloud Dr Ganesh Neelakanta Iyer Amrita Vishwa Vidyapeetham, Coimbatore Associate Professor, Dept of Computer Science and Engg
- 2. About Me • Associate Professor, Amrita Vishwa Vidyapeetham • Masters & PhD from National University of Singapore (NUS) • Several years in Industry/Academia • Sasken Communications, NXP Semiconductors, Progress Software, IIIT-HYD, NUS (Singapore) • Architect, Manager, Technology Evangelist, Visiting Faculty • Talks/workshops in USA, Europe, Australia, Asia • Cloud/Edge Computing, IoT, Game Theory, Software QA • Kathakali Artist, Composer, Speaker, Traveler, Photographer GANESHNIYER http://ganeshniyer.com
- 3. Outline • Dockers • Need for Orchestration • Kubernetes
- 4. How many worked on Kubernetes? Dr Ganesh Neelakanta Iyer 4
- 5. How many of you have worked on Dockers? Dr Ganesh Neelakanta Iyer 5
- 6. How many of you have heard of dockers?
- 7. How many know what is Cloud Computing?
- 8. Dockers
- 9. Flashback – Lets go back to pre-1960’s
- 12. ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Also an M x N Matrix
- 13. Multiplicityof Goods Multiplicityof methodsfor transporting/storing DoIworryabout howgoodsinteract (e.g.coffeebeans nexttospices) CanItransport quicklyand smoothly (e.g.fromboatto traintotruck) Solution: Intermodal Shipping Container …in between, can be loaded and unloaded, stacked, transported efficiently over long distances, and transferred from one mode of transport to another A standard container that is loaded with virtually any goods, and stays sealed until it reaches final delivery.
- 14. This eliminated the M x N problem…
- 15. and spawned an Intermodal Shipping Container Ecosystem • 90% of all cargo now shipped in a standard container • Order of magnitude reduction in cost and time to load and unload ships • Massive reduction in losses due to theft or damage • Huge reduction in freight cost as percent of final goods (from >25% to <3%) massive globalizations • 5000 ships deliver 200M containers per year
- 16. Static website Web frontend User DB Queue Analytics DB Background workers API endpoint nginx 1.5 + modsecurity + openssl + bootstrap 2 postgresql + pgv8 + v8 hadoop + hive + thrift + OpenJDK Ruby + Rails + sass + Unicorn Redis + redis-sentinel Python 3.0 + celery + pyredis + libcurl + ffmpeg + libopencv + nodejs + phantomjs Python 2.7 + Flask + pyredis + celery + psycopg + postgresql-client Development VM QA server Public Cloud Disaster recovery Contributor’s laptop Production Servers The Challenge Multiplicityof Stacks Multiplicityof hardware environments Production Cluster Customer Data Center Doservicesand appsinteract appropriately? CanImigrate smoothlyand quickly?
- 17. Results in M x N compatibility nightmare Static website Web frontend Background workers User DB Analytics DB Queue Development VM QA Server Single Prod Server Onsite Cluster Public Cloud Contributor’s laptop Customer Servers ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
- 18. Static website Web frontendUser DB Queue Analytics DB Development VM QA server Public Cloud Contributor’s laptop Docker is a shipping container system for code Multiplicityof Stacks Multiplicityof hardware environments Production Cluster Customer Data Center Doservicesand appsinteract appropriately? CanImigrate smoothlyand quickly …that can be manipulated using standard operations and run consistently on virtually any hardware platform An engine that enables any payload to be encapsulated as a lightweight, portable, self-sufficient container…
- 19. Static website Web frontendUser DB Queue Analytics DB Development VM QA server Public Cloud Contributor’s laptop Or…put more simply Multiplicityof Stacks Multiplicityof hardware environments Production Cluster Customer Data Center Doservicesand appsinteract appropriately? CanImigrate smoothlyand quickly Operator: Configure Once, Run Anything Developer: Build Once, Run Anywhere (Finally)
- 20. Static website Web frontend Background workers User DB Analytics DB Queue Development VM QA Server Single Prod Server Onsite Cluster Public Cloud Contributor’s laptop Customer Servers Docker solves the M x N problem
- 21. Docker containers • Wrap up a piece of software in a complete file system that contains everything it needs to run: – Code, runtime, system tools, system libraries – Anything you can install on a server • This guarantees that it will always run the same, regardless of the environment it is running in
- 22. Why containers matter Physical Containers Docker Content Agnostic The same container can hold almost any type of cargo Can encapsulate any payload and its dependencies Hardware Agnostic Standard shape and interface allow same container to move from ship to train to semi-truck to warehouse to crane without being modified or opened Using operating system primitives (e.g. LXC) can run consistently on virtually any hardware—VMs, bare metal, openstack, public IAAS, etc.—without modification Content Isolation and Interaction No worry about anvils crushing bananas. Containers can be stacked and shipped together Resource, network, and content isolation. Avoids dependency hell Automation Standard interfaces make it easy to automate loading, unloading, moving, etc. Standard operations to run, start, stop, commit, search, etc. Perfect for devops: CI, CD, autoscaling, hybrid clouds Highly efficient No opening or modification, quick to move between waypoints Lightweight, virtually no perf or start-up penalty, quick to move and manipulate Separation of duties Shipper worries about inside of box, carrier worries about outside of box Developer worries about code. Ops worries about infrastructure.
- 23. Docker containers Lightweight • Containers running on one machine all share the same OS kernel • They start instantly and make more efficient use of RAM • Images are constructed from layered file systems • They can share common files, making disk usage and image downloads much more efficient Open • Based on open standards • Allowing containers to run on all major Linux distributions and Microsoft OS with support for every infrastructure Secure • Containers isolate applications from each other and the underlying infrastructure while providing an added layer of protection for the application
- 24. Docker / Containers vs. Virtual Machine https://www.docker.com/whatisdocker/ Containers have similar resource isolation and allocation benefits as VMs but a different architectural approach allows them to be much more portable and efficient
- 25. Virtual Machines Virtual machines run guest operating systems—note the OS layer in each box. This is resource intensive, and the resulting disk image and application state is an entanglement of OS settings, system-installed dependencies, OS security patches, and other easy-to-lose, hard-to-replicate ephemera Containers vs Virtual Machines Containers Containers can share a single kernel, and the only information that needs to be in a container image is the executable and its package dependencies, which never need to be installed on the host system. These processes run like native processes, and you can manage them individually
- 26. Why are Docker containers lightweight? Bins/ Libs App A Original App (No OS to take up space, resources, or require restart) AppΔ Bins / App A Bins/ Libs App A’ Gues t OS Bins/ Libs Modified App Union file system allows us to only save the diffs Between container A and container A’ VMs Every app, every copy of an app, and every slight modification of the app requires a new virtual server App A Guest OS Bins/ Libs Copy of App No OS. Can Share bins/libs App A Guest OS Guest OS VMs Containers
- 27. What are the basics of the Docker system? Source Code Repository Dockerfile For A Docker Engine Docker Container Image Registry Build Docker Engine Host 2 OS 2 (Windows / Linux) Container A Container B Container C ContainerA Push Search Pull Run Host 1 OS (Linux)
- 28. Changes and Updates Docker Engine Docker Container Image Registry Docker Engine Push Update Bins/ Libs App A AppΔ Bins / Base Container Image Host is now running A’’ Container Mod A’’ AppΔ Bins / Bins/ Libs App A Bins / Bins/ Libs App A’’ Host running A wants to upgrade to A’’. Requests update. Gets only diffs Container Mod A’
- 29. Easily Share and Collaborate on Applications • Distribute and share content – Store, distribute and manage your Docker images in your Docker Hub with your team – Image updates, changes and history are automatically shared across your organization. • Simply share your application with others – Ship your containers to others without worrying about different environment dependencies creating issues with your application. – Other teams can easily link to or test against your app without having to learn or worry about how it works. Docker creates a common framework for developers and sysadmins to work together on distributed applications
- 30. Get Started with Docker • Install Docker • Run a software image in a container • Browse for an image on Docker Hub • Create your own image and run it in a container • Create a Docker Hub account and an image repository • Create an image of your own • Push your image to Docker Hub for others to use https://www.docker.com/products/docker https://www.docker.com/products/docker-toolbox
- 31. Docker Container as a Service (CaaS) Deliver an IT secured and managed application environment for developers to build and deploy applications in a self service manner
- 34. Continuous Integration and Deployment (CI / CD)
- 37. How does this help you build better software? • Stop wasting hours trying to setup developer environments • Spin up new instances and make copies of production code to run locally • With Docker, you can easily take copies of your live environment and run on any new endpoint running Docker. Accelerate Developer Onboarding • The isolation capabilities of Docker containers free developers from the worries of using “approved” language stacks and tooling • Developers can use the best language and tools for their application service without worrying about causing conflict issues Empower Developer Creativity • By packaging up the application with its configs and dependencies together and shipping as a container, the application will always work as designed locally, on another machine, in test or production • No more worries about having to install the same configs into a different environment Eliminate Environment Inconsistencies
- 40. Setting up • Before we get started, make sure your system has the latest version of Docker installed. • Docker is available in two editions: Community Edition (CE) and Enterprise Edition (EE). • Docker Community Edition (CE) is ideal for developers and small teams looking to get started with Docker and experimenting with container-based apps. Docker CE has two update channels, stable and edge: – Stable gives you reliable updates every quarter – Edge gives you new features every month • Docker Enterprise Edition (EE) is designed for enterprise development and IT teams who build, ship, and run business critical applications in production at scale.
- 42. In this session, I use Docker for Windows Desktop
- 44. If your windows is not in latest version… https://docs.docker.com/docker-for-windows/release-notes/#docker-community-edition-17062-ce-win27-2017-09-06-stable
- 45. Docker for Windows When the whale in the status bar stays steady, Docker is up-and-running, and accessible from any terminal window.
- 46. Hello-world • Open command prompt / windows power shell and run docker run hello-world ▪ Now would also be a good time to make sure you are using version 1.13 or higher. Run docker --version to check it out.
- 47. Building an app the Docker way • In the past, if you were to start writing a Python app, your first order of business was to install a Python runtime onto your machine • But, that creates a situation where the environment on your machine has to be just so in order for your app to run as expected; ditto for the server that runs your app • With Docker, you can just grab a portable Python runtime as an image, no installation necessary • Then, your build can include the base Python image right alongside your app code, ensuring that your app, its dependencies, and the runtime, all travel together • These portable images are defined by something called a Dockerfile
- 48. Define a container with a Dockerfile • Dockerfile will define what goes on in the environment inside your container • Access to resources like networking interfaces and disk drives is virtualized inside this environment, which is isolated from the rest of your system, so you have to map ports to the outside world, and be specific about what files you want to “copy in” to that environment • However, after doing that, you can expect that the build of your app defined in this Dockerfile will behave exactly the same wherever it runs
- 49. Dockerfile • Create an empty directory • Change directories (cd) into the new directory, create a file called Dockerfile
- 50. Dockerfile • In windows, open notepad, copy the content below, click on Save as, type “Dockerfile” This Dockerfile refers to a couple of files we haven’t created yet, namely app.py and requirements.txt. Let’s create those next.
- 51. The app itself • Create two more files, requirements.txt and app.py, and put them in the same folder with the Dockerfile • This completes our app, which as you can see is quite simple • When the above Dockerfile is built into an image, app.py and requirements.txt will be present because of that Dockerfile’s ADD command, and the output from app.py will be accessible over HTTP thanks to the EXPOSE command.
- 52. The App itself Requirements.txt app.py That’s it! You don’t need Python or anything in requirements.txt on your system, nor will building or running this image install them on your system. It doesn’t seem like you’ve really set up an environment with Python and Flask, but you have.
- 53. Building the app • We are ready to build the app. Make sure you are still at the top level of your new directory. Here’s what ls should show • Now run the build command. This creates a Docker image, which we’re going to tag using -t so it has a friendly name.
- 54. Building the app • docker build -t friendlyhello .
- 55. Where is your built images? • docker images
- 56. Run the app • Run the app, mapping your machine’s port 4000 to the container’s published port 80 using –p • docker run -p 4000:80 friendlyhello • You should see a notice that Python is serving your app at http://0.0.0.0:80. But that message is coming from inside the container, which doesn’t know you mapped port 80 of that container to 4000, making the correct URL http://localhost:4000 • Go to that URL in a web browser to see the display content served up on a web page, including “Hello World” text, the container ID, and the Redis error message
- 58. End the process • Hit CTRL+C in your terminal to quit • Now use docker stop to end the process, using the CONTAINER ID, like so
- 59. • Now let’s run the app in the background, in detached mode: • docker run -d -p 4000:80 friendlyhello • You get the long container ID for your app and then are kicked back to your terminal. Your container is running in the background. You can also see the abbreviated container ID with docker container ls (and both work interchangeably when running commands): • docker container ls
- 60. Share image • To demonstrate the portability of what we just created, let’s upload our built image and run it somewhere else • After all, you’ll need to learn how to push to registries when you want to deploy containers to production • A registry is a collection of repositories, and a repository is a collection of images—sort of like a GitHub repository, except the code is already built. An account on a registry can create many repositories. The docker CLI uses Docker’s public registry by default • If you don’t have a Docker account, sign up for one at cloud.docker.com. Make note of your username.
- 63. Login with your docker id • Log in to the Docker public registry on your local machine. • docker login
- 64. Tag the image • The notation for associating a local image with a repository on a registry is username/repository:tag. The tag is optional, but recommended, since it is the mechanism that registries use to give Docker images a version. Give the repository and tag meaningful names for the context, such as get-started:part1. This will put the image in the get-started repository and tag it as part1. • Now, put it all together to tag the image. Run docker tag image with your username, repository, and tag names so that the image will upload to your desired destination. The syntax of the command is:
- 65. Tag the image
- 66. Publish the image • Upload your tagged image to the repository • docker push username/repository:tag • Once complete, the results of this upload are publicly available. If you log in to Docker Hub, you will see the new image there, with its pull command
- 67. Publish the image • Upload your tagged image to the repository • docker push username/repository:tag • Once complete, the results of this upload are publicly available. If you log in to Docker Hub, you will see the new image there, with its pull command
- 69. Pull and run the image from the remote repository • From now on, you can use docker run and run your app on any machine with this command: • docker run -p 4000:80 username/repository:tag • If the image isn’t available locally on the machine, Docker will pull it from the repository. • If you don’t specify the :tag portion of these commands, the tag of :latest will be assumed, both when you build and when you run images. Docker will use the last version of the image that ran without a tag specified (not necessarily the most recent image). No matter where executes, it pulls your image, along with Python and all the dependencies from , and runs your code. It all travels together in a neat little package, and the host machine doesn’t have to install anything but Docker to run it.
- 70. What have you seen so far? • Basics of Docker • How to create your first app in the Docker way • Building the app • Run the app • Sharing and Publishing images • Pull and run images
- 72. The Need for Orchestration Systems • While Docker provided an open standard for packaging and distributing containerized applications, there arose a new problem – How would all of these containers be coordinated and scheduled? – How do all the different containers in your application communicate with each other? – How can container instances be scaled? Dr Ganesh Neelakanta Iyer 72
- 73. Solution Container Orchestration Systems Dr Ganesh Neelakanta Iyer 73
- 74. From Containers to Kubernetes VM Host OS Container Runtime Benefits Isolation Immutable infrastructure Portability Faster deployments Versioning Ease of sharing Challenges Networking Deployments Service Discovery Auto Scaling Persisting Data Logging, Monitoring Access Control Kubernetes Orchestration of cluster of containers across multiple hosts • Automatic placements, networking, deployments, scaling, roll-out/-back, A/B testing Docker Workload Portability • Abstract from cloud provider specifics • Multiple container runtimes Declarative – not procedural • Declare target state, reconcile to desired state • Self-healing Container Scheduler Container
- 75. Kubernetes • Kubernetes is an open-source container cluster manager – originally developed by Google, donated to the Cloud Native Computing Foundation – schedules & deploys containers onto a cluster of machines • e.g. ensure that a specified number of instances of an application are running – provides service discovery, distribution of configuration & secrets, ... – provides access to persistent storage • Pod – smallest deployable unit of compute – consists of one or more containers that are always co-located, co- scheduled & run in a shared context 5
- 76. Why Kubernetes? • It can be run anywhere – on-premises • bare metal, OpenStack, ... – public clouds • Google, Azure, AWS, ... • Aim is to use Kubernetes as an abstraction layer – migrate to containerised applications managed by Kubernetes & use only the Kubernetes API – can then run out-of-the-box on any Kubernetes cluster • Avoid vendor lock-in as much as possible by not using any vendor specific APIs or services – except where Kubernetes provides an abstraction • e.g. storage, load balancers 7
- 77. Kubernetes Architecture Dr Ganesh Neelakanta Iyer 77https://www.slideshare.net/janakiramm/kubernetes-architecture
- 78. Kubernetes Master Dr Ganesh Neelakanta Iyer 78https://www.slideshare.net/janakiramm/kubernetes-architecture
- 79. kube-apiserver • The apiserver provides a forward facing REST interface into the kubernetes control plane and datastore • All clients, including nodes, users and other applications interact with kubernetes strictly through the API Server • It is the true core of Kubernetes acting as the gatekeeper to the cluster by handling authentication and authorization, request validation, mutation, and admission control in addition to being the front-end to the backing datastore Dr Ganesh Neelakanta Iyer 79
- 80. etcd • Etcd acts as the cluster datastore • Providing a strong, consistent and highly available key- value store used for persisting cluster state Dr Ganesh Neelakanta Iyer 80
- 81. kube-controller-manager • The controller-manager is the primary daemon that manages all core component control loops • It monitors the cluster state via the apiserver and steers the cluster towards the desired state • These controllers include: – Node Controller: Responsible for noticing and responding when nodes go down. – Replication Controller: Responsible for maintaining the correct number of pods for every replication controller object in the system. – Endpoints Controller: Populates the Endpoints object (that is, joins Services & Pods). – Service Account & Token Controllers: Create default accounts and API access tokens for new namespaces Dr Ganesh Neelakanta Iyer 81
- 82. cloud-controller-manager • cloud-controller-manager runs controllers that interact with the underlying cloud providers • cloud-controller-manager allows cloud vendors code and the Kubernetes code to evolve independent of each other Dr Ganesh Neelakanta Iyer 82
- 83. kube-scheduler • Kube-scheduler is a verbose policy-rich engine that evaluates workload requirements and attempts to place it on a matching resource • These requirements can include such things as general hardware reqs, affinity, anti-affinity, and other custom resource requirements Dr Ganesh Neelakanta Iyer 83
- 84. Kubernetes Node Dr Ganesh Neelakanta Iyer 84https://www.slideshare.net/janakiramm/kubernetes-architecture
- 85. Pod • A Pod is the basic building block of Kubernetes–the smallest and simplest unit in the Kubernetes object model that you create or deploy • A Pod represents a running process on your cluster • A Pod encapsulates an application container (or, in some cases, multiple containers), storage resources, a unique network IP, and options that govern how the container(s) should run • A Pod represents a unit of deployment: a single instance of an application in Kubernetes, which might consist of either a single container or a small number of containers that are tightly coupled and that share resources Dr Ganesh Neelakanta Iyer 85
- 86. kubelet • An agent that runs on each node in the cluster. It makes sure that containers are running in a pod. • The kubelet takes a set of PodSpecs that are provided through various mechanisms and ensures that the containers described in those PodSpecs are running and healthy. The kubelet doesn’t manage containers which were not created by Kubernetes Dr Ganesh Neelakanta Iyer 86
- 87. kube-proxy • Enables the Kubernetes service abstraction by maintaining network rules on the host and performing connection forwarding Dr Ganesh Neelakanta Iyer 87
- 88. Container Runtime • The container runtime is the software that is responsible for running containers • Kubernetes supports several runtimes – Docker, rkt, runc and any OCI runtime-spec implementation Dr Ganesh Neelakanta Iyer 88
- 89. Kubernetes Cluster Dr Ganesh Neelakanta Iyer 89 • Kubernetes coordinates a highly available cluster of computers that are connected to work as a single unit • Kubernetes automates the distribution and scheduling of application containers across a cluster in a more efficient way
- 90. Running Kubernetes Locally via Minikube • Minikube is a tool that makes it easy to run Kubernetes locally • Minikube runs a single-node Kubernetes cluster inside a VM on your laptop for users looking to try out Kubernetes or develop with it day-to-day Dr Ganesh Neelakanta Iyer 90
- 91. Hello Minikube
- 92. Hello Minicube • This tutorial provides a container image built from the following files Dr Ganesh Neelakanta Iyer 92
- 93. Create a minikube cluster • minikube version • minikube start • minikube dashboard Dr Ganesh Neelakanta Iyer 93
- 94. Create a Deployment • A Kubernetes Pod is a group of one or more Containers, tied together for the purposes of administration and networking • The Pod in this tutorial has only one Container • A Kubernetes Deployment checks on the health of your Pod and restarts the Pod’s Container if it terminates • Deployments are the recommended way to manage the creation and scaling of Pods Dr Ganesh Neelakanta Iyer 94
- 95. Create a Deployment • Use the kubectl create command to create a Deployment that manages a Pod • The Pod runs a Container based on the provided Docker image kubectl create deployment hello-node --image= gcr.io/hello-minikube-zero-install/hello-node Dr Ganesh Neelakanta Iyer 95
- 96. Create a Deployment View the deployment kubectl get deployments Dr Ganesh Neelakanta Iyer 96
- 97. Create a Deployment • View the Pod kubectl get pods Dr Ganesh Neelakanta Iyer 97
- 98. Create a deployment • View cluster events kubectl get events • View the kubectl configuration kubectl config view Dr Ganesh Neelakanta Iyer 98
- 99. Create s Service • By default, the Pod is only accessible by its internal IP address within the Kubernetes cluster • To make the hello-node Container accessible from outside the Kubernetes virtual network, you have to expose the Pod as a Kubernetes Service • Expose the Pod to the public internet using the kubectl expose command kubectl expose deployment hello-node --type=LoadBalancer --port=8080 Dr Ganesh Neelakanta Iyer 99
- 100. Create a Service • View the Service you just created kubectl get services Dr Ganesh Neelakanta Iyer 100
- 101. Run a Service • Run the following command minikube service hello-node Dr Ganesh Neelakanta Iyer 101
- 102. Bigger Experiment with Kubernetes
- 103. Deploying PHP Guestbook application with Redis
- 104. Deploying PHP Guestbook application with Redis • This tutorial shows you how to build and deploy a simple, multi-tier web application using Kubernetes and Docker • This example consists of the following components: – A single-instance Redis master to store guestbook entries – Multiple replicated Redis instances to serve reads – Multiple web frontend instances Dr Ganesh Neelakanta Iyer 104
- 105. Objectives • Start up a Redis master • Start up Redis slaves • Start up the guestbook frontend • Expose and view the Frontend Service Dr Ganesh Neelakanta Iyer 105
- 106. Start up the Redis Master • The guestbook application uses Redis to store its data • It writes its data to a Redis master instance and reads data from multiple Redis slave instances • Creating the Redis Master Deployment • Copy the folder here to your system https://tinyurl.com/anokadockers Dr Ganesh Neelakanta Iyer 106
- 107. *.yaml file Dr Ganesh Neelakanta Iyer 107
- 108. Start up the Redis Master • Launch a terminal window in the directory you downloaded the manifest files • Apply the Redis Master Deployment from the redis- master-deployment.yaml file kubectl apply -f redis-master-deployment.yaml Dr Ganesh Neelakanta Iyer 108
- 109. Start up the Redis Master • Query the list of Pods to verify that the Redis Master Pod is running: kubectl get pods Dr Ganesh Neelakanta Iyer 109
- 110. Run the following command to view the logs from the Redis Master Pod kubectl logs -f POD-NAME Dr Ganesh Neelakanta Iyer 110 Replace POD-NAME with the name of your Pod
- 111. Creating the Redis Master Service • The guestbook applications needs to communicate to the Redis master to write its data • You need to apply a Service to proxy the traffic to the Redis master Pod • A Service defines a policy to access the Pods • Launch a terminal window in the directory you downloaded the manifest files • Apply the Redis Master Service from the following redis-master- service.yaml file kubectl apply -f redis-master-service.yaml Dr Ganesh Neelakanta Iyer 111
- 112. Creating the Redis Master Service • Query the list of Services to verify that the Redis Master Service is running • kubectl get service Dr Ganesh Neelakanta Iyer 112
- 113. Start up the Redis Slaves • Although the Redis master is a single pod, you can make it highly available to meet traffic demands by adding replica Redis slaves Dr Ganesh Neelakanta Iyer 113
- 114. Creating the Redis Slave Deployment • Deployments scale based off of the configurations set in the manifest file. In this case, the Deployment object specifies two replicas • If there are not any replicas running, this Deployment would start the two replicas on your container cluster • Conversely, if there are more than two replicas are running, it would scale down until two replicas are running Dr Ganesh Neelakanta Iyer 114
- 115. Creating the Redis Slave Deployment • Apply the Redis Slave Deployment from the redis-slave- deployment.yaml file kubectl apply -f redis-slave-deployment.yaml Dr Ganesh Neelakanta Iyer 115
- 116. Creating the Redis Slave Deployment • Query the list of Pods to verify that the Redis Slave Pods are running: kubectl get pods Dr Ganesh Neelakanta Iyer 116
- 117. Creating the Redis Slave Service • The guestbook application needs to communicate to Redis slaves to read data • To make the Redis slaves discoverable, you need to set up a Service • A Service provides transparent load balancing to a set of Pods Dr Ganesh Neelakanta Iyer 117
- 118. Creating the Redis Slave Service • Apply the Redis Slave Service from the following redis- slave-service.yaml file kubectl apply -f redis-slave-service.yaml Dr Ganesh Neelakanta Iyer 118
- 119. Creating the Redis Slave Service • Query the list of Services to verify that the Redis slave service is running kubectl get services Dr Ganesh Neelakanta Iyer 119
- 120. Set up and Expose the Guestbook Frontend • The guestbook application has a web frontend serving the HTTP requests written in PHP • It is configured to connect to the redis-master Service for write requests and the redis-slave service for Read requests Dr Ganesh Neelakanta Iyer 120
- 121. Creating the Guestbook Frontend Deployment • Apply the frontend Deployment from the frontend- deployment.yaml file kubectl apply -f frontend-deployment.yaml Dr Ganesh Neelakanta Iyer 121
- 122. Creating the Guestbook Frontend Deployment • Query the list of Pods to verify that the three frontend replicas are running kubectl get pods -l app=guestbook -l tier=frontend Dr Ganesh Neelakanta Iyer 122
- 123. Creating the frontend service • The redis-slave and redis-master Services you applied are only accessible within the container cluster because the default type for a Service is ClusterIP • ClusterIP provides a single IP address for the set of Pods the Service is pointing to • This IP address is accessible only within the cluster. • If you want guests to be able to access your guestbook, you must configure the frontend Service to be externally visible, so a client can request the Service from outside the container cluster • Minikube can only expose Services through NodePort Dr Ganesh Neelakanta Iyer 123
- 124. Creating the frontend service • Apply the frontend Service from the frontend-service.yaml file kubectl apply -f frontend-service.yaml Dr Ganesh Neelakanta Iyer 124
- 125. Creating the frontend service • Query the list of Services to verify that the frontend Service is running kubectl get services Dr Ganesh Neelakanta Iyer 125
- 126. Viewing the Frontend Service via NodePort • If you deployed this application to Minikube or a local cluster, you need to find the IP address to view your Guestbook • Run the following command to get the IP address for the frontend Service minikube service frontend --url Dr Ganesh Neelakanta Iyer 126
- 127. Go to a browser and type that URL Dr Ganesh Neelakanta Iyer 127
- 128. Viewing the Frontend Service via LoadBalancer • If you deployed the frontend-service.yaml manifest with type: LoadBalancer you need to find the IP address to view your Guestbook • Run the following command to get the IP address for the frontend Service kubectl get service frontend Dr Ganesh Neelakanta Iyer 128
- 129. Scale the Web Frontend • Scaling up or down is easy because your servers are defined as a Service that uses a Deployment controller • Run the following command to scale up the number of frontend Pods: kubectl scale deployment frontend --replicas=5 • Query the list of Pods to verify the number of frontend Pods running: kubectl get pods Dr Ganesh Neelakanta Iyer 129
- 130. Summary • Kubernetes can help you – Create clusters – Deploy applications – Scale your business Dr Ganesh Neelakanta Iyer 130
- 133. Dr Ganesh Neelakanta Iyer ni_amrita@cb.amrita.edu ganesh.vigneswara@gmail.com GANESHNIYER