Skip to main content

Kubernetes: 10. Node Selector

Scheduler

  • By default Pods gets scheduled based on node availability for the scheduler
  • There may be cases where in one of the node has more resources and the pod required to be scheduled on this node
  • There are two ways to achieve this
    1. Node Selector
    2. Node Affinity
Node Selector
  • Update the pod definition file with the node selector label
  • Pod will be scheduled on the node matching the label
  • But first, Node has to be labelled. 
  • Within the pod definition spec.nodeSelector is the property to map a pod to a node
  • With node selector, you can only have a simple key-value selection
  • There are no options for advanced selectors like label in certain values, or label not-in a value
pod-definition.yaml
apiVersion: v1
kind: Pod
metadata:
    name: myapp-pod
    labels:
        app: myapp

spec:
    containers:
    - name: nginx-container
      image: nginx

    nodeSelector:
        size: Large
  
kubectl label node <node-name> <label-key>=<label-value> 
-> Set a node label with key value pair

kubectl label node node01 size=Large 
-> Set node01 label size to Large value
Labels:

Comments

Post a Comment

Popular posts from this blog

Azure Active Directory

Azure Active directory (AAD) is a Identity as a Service. This is a smaller subset of Active directory. This is not a replacement to active directory at all. Azure active directory provides the identity services to the mobile apps and web apps in Private cloud. These apps may be connected to on-premise applications. So an SSO is enabled for these apps. So Azure active directory has very simple functionality. Create Users, Groups. Map groups to network security groups and provide the authentication to the resources. When you login to Azure portal, right upper corner of the screen has username along with the domain. Domain or tenant or organization are used interchangeably. Management of Users and Groups: Cloud identity (create users manually)  Directory synchronized identifiers (users are synchronized)  Add users Adding a cloud identity users makes the user as Guest When you do directory synchronization on Premise AD Groups are synched up wi...
Post a Comment
Read more

Kubernetes: 19. Configure Application

Configuring application consists of Configuring commands and arguments on applications Configuring environment variables Configuring secrets Docker Commands docker run ubuntu  -> Runs ubuntu container and exit, container CMD is set to [bash], so the container quitely exits docker run ubuntu echo "Hello World" -> Runs ubuntu container, prints "Hello World" exits quitely. To update the default settings, create your own image from the base image lets call this ubuntu-sleeper image FROM ubuntu CMD sleep 5 CMD can also be mentioned in the JSON format like CMD ["sleep", "5"] Note that with JSON format the first element should always be the command to execute,  for eg, it CANNOT be ["sleep 5"] Run build the new ubuntu-sleeper image and run the new image docker build -t ubuntu-sleeper .  -> Build the image docker run ubuntu-sleeper -> Run the new image So the new image will launch ubuntu container, sleep for 5 seconds and quitely ex...
Post a Comment
Read more

Kubernetes: 15. Multiple Schedulers

Custom Scheduler Kubernetes allows to create custom schedulers There can be multiple schedulers running at a same time apart from the default scheduler or A custom scheduler can replace the default kube-scheduler to become the default one So a few pods that requires additional checks apart from taints and toleration, node affinity can go through the custom scheduler before getting scheduled on the node Whereas the rest of the pods can go through the default kube-scheduler Create Custom Scheduler We can either download the kube-scheduler and run it as a service or alternatively create it using a static pod Below here we are downloading the binaries to run it The property scheduler-name is used to define the name of the scheduler, if not set then it will be defaulted to default-scheduler For your custom schedulers, update this property name to set a custom name for your scheduler For Static pods, the name can be updated directly in the pod-definition file Use kubectl create -f <pod-de...
Post a Comment
Read more