Skip to main content

Kubernetes: 6. Imperative Commands

  • Imperative commands are useful in quickly creating the resources on Kubernetes
kubectl
--dry-run -> When created with this option, Kubernetes just validates the definition and does not actually create the resource
-o=yaml -> Gets the output in YAML format

kubectl run nginx-pod --image=nginx:alpine 
-> Create a pod with name nginx-pod and image nginx:alpine

kubectl run httpd --image=httpd:alpine 
-> By default, run implies run-a-pod

kubectl run redis --image=redis:alpine --labels=tier=db 
-> Create a pod with name redis and image redis:alpine and labels set to tier=db

kubectl run custom-nginx --image=nginx --port=8080 
-> Create a pod with name custom-nginx and image nginx to run on port 8080

kubectl expose pod redis --port=6379 --name=redis-service 
-> Create a service with name redis-service to expose pod named redis on service-port 6379

kubectl create deployment webapp --image=kodekloud/webapp-color --replicas=3 
-> Create a deployment with name webapp and image set with 3 replicas

kubectl create ns dev-ns
-> Create a nanespace dev-ns

kubectl create deployment redis-deploy --namespace=dev-ns --image=redis --replicas=2 
-> Create a deployment

kubectl expose pod httpd --name=httpd --type=ClusterIP --port=80 --target-port=8080 
-> Expose a pod as service of type ClusterIP on the specifed ports  
Labels:

Comments

Post a Comment

Popular posts from this blog

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

Kubernetes: 21. Secrets

Passwords In the webapps we store the properties file for storing and retrieving the data required by application But we never store the application passwords, truststore, keystore passwords etc here We might store them in an encrypted format, but storing them as plain text is not the correct way In Kubernetes we store these sensitive information in Secrets https://medium.com/avmconsulting-blog/secrets-management-in-kubernetes-378cbf8171d0 Secrets Secrets are used to store the sensitive information They are similar to ConfigMaps, except that they are stored in hashed or encoded format Note that they are only encoded (using base64) but are not encrypted So secrets are a safe option to store sensitive information but infact they are not the safest option As such secret objects should be not checked into source code tools, its best to store them encrypted at REST in ETCD Again as in ConfigMaps, we have to create the secrets object first and then inject them into the pods There are 2 ways ...
Post a Comment
Read more