KodeCloud CKA Miscellaneous

Links: 111 KodeCloud Index

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High Availability

• For high availability we need multiple master nodes.
• Multiple master nodes means there will be multiple API servers.
  • API servers can work in active active configuration.
  • We would need a load balancer to balance the requests sent to the API server.
  • Diagram:
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• For the controller manager and scheduler they CANNOT run in active active configuration i.e. multiple instances must not run in parallel.
  • They run in an active standby mode.
  • To achieve the active and standby node leader election process is used.

JSON Path

• Find out what you want to extract using k get pods -o json.
• Provide the JSON path query: k get pods -o jsonpath='{ .root.object[2]}'
• Some examples of JSON path queries:
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  • Using loops
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General Tips

• When we run k run pod --image=nginx the container runtime is actually pulling images from docker.io/library/nginx.
  • Here nginx is the image name.
  • library is the user/account name.
    • library is the name of the default account where docker's official images are stored.
  • docker.io is the default registry from where images are pulled.
    • Google's registry is grc.io where a lot of k8s related images are stored.
  • Diagram:
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FAQs

How to determine the resources required by each pod so that I can specify it in deployment definition file?

• Install the metrics API server and run k top pods.

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Last updated: 2023-06-13