CMD line

Question 1

When creating a service, how is it linked to a pod ?

Answer 1

Via .yaml file config:

selector: app: POD (replace with sed)

Question 2

Difference btw:
Deployment
and
Service

Answer 2

The service is serving a pod,
And a deployment (/workload) is managing a pod.
Deployment is the glue btw service and pod.
See for instance the yaml files:
<a>
deployment</a> vs <a>
service</a>

Question 3

upgrade deployment image

Answer 3

kubectl set image deployment/$DEPLOYMENT $POD=gcr.io/feedly-social/$IMAGE:$VERSION

Question 4

What are the replica sets and how do you get them ?

Answer 4

kubectl get rs

ReplicaSet, like ReplicationController, ensures that a specified number of pods replicas are running at one time. ReplicaSet supports the new set-based selector requirements as described in the labels user guide, whereas a Replication Controller only supports equality-based selector requirements

Question 5

When is the Dockerfile executed ?

Answer 5

When we run build my_image

Question 6

What is the FROM cmd line fro ?

Answer 6

You must always specify at the beginning of a Docker file, the image from which you are building : eg. FROM centos:centos7, FROM ml-common, ect…

Question 7

How does canary work ? Why do we need a canary pool ?

Answer 7

The rolling update is done automatically.

Question 8

What is an “object” ?

Are all objects in a namespace ?

Answer 8

An object is a resource (?), eg. pods, services, replication controllers, and others.

Most Kubernetes resources (e.g. pods, services, replication controllers, and others) are in some namespaces. However namespace resources are not themselves in a namespace. And low-level resources, such as nodes and persistentVolumes, are not in any namespace.