Kubernetes is open-source orchestration software for deploying, managing, and scaling containers. Here, I have done handson experience on Minikube, is a tool that makes it easy to run Kubernetes locally. Minikube runs a single-node Kubernetes cluster inside a Virtual Machine (VM)(I used VM ware work stationplayer ) on your laptop for users looking to try out Kubernetes or develop with it day-to-day.
Creating running and sharing a container image
- Create the app a. Creating a trivial Node.js app b. Creating a Docker file for the image
- Building the container image
- Running the container image Exploring the inside of a running container Pushing the image to an image registry
RUNNING YOUR FIRST APP ON KUBERNETES Step :1 Starting a Minikube virtual machine Step:2Displaying cluster information Step:3 Deploying your Node.js app Step:4 Listing pods. Step:5 Creating a Service object & Listing Services Step:6 Horizontally scaling the application Step:7 Examining what nodes your app is running on.
Creating a simple YAML descriptor for a pod, Viewing application logs, Sending requests to the pod, Specifying labels when creating a pod, Overwrite labels: Listing pods using a label selector, Using labels for categorizing worker nodes, Looking up an object’s annotations, Discovering other namespaces and their pods, Creating a namespace Managing objects in other namespaces, Deleting a pod by name, Deleting pods by deleting the whole namespace, Deleting all pods in a namespace, while keeping the namespace, Deleting (almost) all resources in a namespace,
Contain week 6.pdf Create Nodejs app called “app.js” and Docker file Create Docker image Push the docker image to docker hub. Creating an HTTP-based liveness probe Create a pod from the kubia-liveness-probe.yaml Seeing a liveness probe in action Here the kubia-livness pod restarted 2 times. We can obtain the logs of previous container by running kubectl logs “kubia-liveness” --previous. Description after pod restarted: Configuring additional properties of the liveness probe liveness probe with an initial delay Pod describe shows the delay of 15s Introducing Replication Controllers Creating a Replication Controller Seeing the Replication Controller in action Getting information about a Replication Controller Displaying details of a Replication Controller with kubectl describe Moving pods in and out of the scope of a Replication Controller Changing the pod template Horizontally scaling pods Scaling down with the kubectl scale command Deleting a Replication Controller Creating and examining a Replica Set Using the Replicase’s more expressive label selectors Wrapping up Replica Sets Daemon Set: Adding the required label to your node (s Removing the required label from the node Defining a Job resource Running multiple pod instances in a Job Cronjob Understanding how scheduled jobs are run
Setting environment variables for a container Making the interval in your fortune image configurable through an- n environment variable Step-1: Fortune script with interval configurable through environment variable. Step-2: Docker file for the updated fortune image Step-3: Build Docker image and push the image to DockerHub. Step-4: Create pod from fortune-pod-env.yaml Step-5: Logs to prove environment variable usage in Pod’s container
Step-1: Different ways to create ConfigMap a) Using the kubectl create configmap command and display yaml. b) Creating a ConfigMap entry from yaml. c) Creating a ConfigMap entry from the contents of a file d) Creating a ConfigMap from files in a directory e) Combining different options Step-2: Passing a ConfigMap entry to a container as an environment variable Logs to prove: Step-3: Passing all entries of a ConfigMap as environment variables at once Step-4: Passing a ConfigMap entry as a command-line argument Step-5: Using a configMap volume to expose ConfigMap entries as files a) Creating the ConfigMap b) Using the ConfigMap’s entries in a volume c) Exposing certain ConfigMap entries in the volume d) Setting file permissions Step-6: Updating an app’s config without having to restart the app a) Editing a ConfigMap b) Signaling Nginx to reload the config c) Understanding how the files are updated atomically
Introducing the default token Secret Creating a Secret Comparing ConfigMaps and Secrets Using the Secret in a pod.
Understanding secret volumes are stored in memory Understanding image pull Secrets Creating a Secret for authenticating with a Docker registry Using the docker-registry Secret in a pod definition
Exposing metadata through environment variables Downward API used in environment variables: downward-api-env.yaml If your "downward" pod is not coming up and getting stuck at "ContainerCreating", then this is due the "CPU & Memory" limit set under resources in "downward-api-env.yaml" file. The limits are really low for today's VM on which your kubernetes cluster is running. So that is the reason the creation of pod is failing. Solution: Remove the resources in downward-api-env.yaml file. Environment variables in the downward pod
Pod with a downwardAPI volume: downward-api-volume.yaml Files in the downwardAPI volume Displaying labels and annotations in the downwardAPI volume
Exploring the Kubernetes REST API Accessing the API server through kubectl proxy Exploring the Kubernetes API through the kubectl proxy Exploring the batch API group’s REST endpoint You probably have no Job resources deployed in your cluster, so the items array will be empty. You can try deploying the Job in Chapter08/my-job.yaml and hitting the REST endpoint again to get the same output in a item array . Listing all Job instances in the cluster Retrieving a specific Job instance by name