I am trying my hands on Kubernetes and I tried to deploy an image into k8s service
root#KubernetesMiniKube:/usr/local/bin# kubectl run hello-minikube --image=k8s.gcr.io/echoserver:1.10 --port=8080
pod/hello-minikube created
root#KubernetesMiniKube:/usr/local/bin# kubectl get pod
NAME READY STATUS RESTARTS AGE
hello-minikube 1/1 Running 0 16s
root#KubernetesMiniKube:/usr/local/bin# kubectl get deployments
No resources found in default namespace.
Why i am seeing No resource found but actually there is a resource running inside default namespace.
When you are using $ kubectl run it will create a pod.
In your example thats exactly what happned, it created pod, named hello-minikube.
pod/hello-minikube created
If you want to create deployment
Deployments represent a set of multiple, identical Pods with no unique identities. A Deployment runs multiple replicas of your application and automatically replaces any instances that fail or become unresponsive.
you can do it using command:
$ kubectl create deployment hello-minikube --image=k8s.gcr.io/echoserver:1.10 --port=8080
deployment.apps/hello-minikube created
user#cloudshell:$ kubectl get deployments
NAME READY UP-TO-DATE AVAILABLE AGE
hello-minikube 1/1 1 1 8s
You can also create deployment using YAML.
Save YAML from this documentation example and use kubectl apply.
$ vi nginx.yaml
<paste proper YAML definition. Also you can use nano editor, or download ready yaml>
user#cloudshell:$ kubectl apply -f nginx.yaml
deployment.apps/nginx-deployment created
$ kubectl get deployments
NAME READY UP-TO-DATE AVAILABLE AGE
hello-minikube 1/1 1 1 3m48s
nginx-deployment 3/3 3 3 64s
Please let me know if you have further questions regarding this answer.
Related
As the kubernetes.io docs state about a Service of type LoadBalancer:
On cloud providers which support external load balancers, setting the
type field to LoadBalancer provisions a load balancer for your
Service. The actual creation of the load balancer happens
asynchronously, and information about the provisioned balancer is
published in the Service's .status.loadBalancer field.
On AWS Elastic Kubernetes Service (EKS) a an AWS Load Balancer is provisioned that load balances network traffic (see AWS docs & the example project on GitHub provisioning a EKS cluster with Pulumi). Assuming we have a Deployment ready with the selector app=tekton-dashboard (it's the default Tekton dashboard you can deploy as stated in the docs), a Service of type LoadBalancer defined in tekton-dashboard-service.yml could look like this:
apiVersion: v1
kind: Service
metadata:
name: tekton-dashboard-external-svc-manual
spec:
selector:
app: tekton-dashboard
ports:
- protocol: TCP
port: 80
targetPort: 9097
type: LoadBalancer
If we create the Service in our cluster with kubectl apply -f tekton-dashboard-service.yml -n tekton-pipelines, the AWS ELB get's created automatically:
There's only one problem: The .status.loadBalancer field is populated with the ingress[0].hostname field asynchronously and is therefore not available immediately. We can check this, if we run the following commands together:
kubectl apply -f tekton-dashboard-service.yml -n tekton-pipelines && \
kubectl get service/tekton-dashboard-external-svc-manual -n tekton-pipelines --output=jsonpath='{.status.loadBalancer}'
The output will be an empty field:
{}%
So if we want to run this setup in a CI pipeline for example (e.g. GitHub Actions, see the example project's workflow provision.yml), we need to somehow wait until the .status.loadBalancer field got populated with the AWS ELB's hostname. How can we achieve this using kubectl wait?
TLDR;
Prior to Kubernetes v1.23 it's not possible using kubectl wait, but using until together with grep like this:
until kubectl get service/tekton-dashboard-external-svc-manual -n tekton-pipelines --output=jsonpath='{.status.loadBalancer}' | grep "ingress"; do : ; done
or even enhance the command using timeout (brew install coreutils on a Mac) to prevent the command from running infinitely:
timeout 10s bash -c 'until kubectl get service/tekton-dashboard-external-svc-manual -n tekton-pipelines --output=jsonpath='{.status.loadBalancer}' | grep "ingress"; do : ; done'
Problem with kubectl wait & the solution explained in detail
As stated in this so Q&A and the kubernetes issues kubectl wait unable to not wait for service ready #80828 & kubectl wait on arbitrary jsonpath #83094 using kubectl wait for this isn't possible in current Kubernetes versions right now.
The main reason is, that kubectl wait assumes that the status field of a Kubernetes resource queried with kubectl get service/xyz --output=yaml contains a conditions list. Which a Service doesn't have. Using jsonpath here would be a solution and will be possible from Kubernetes v1.23 on (see this merged PR). But until this version is broadly available in managed Kubernetes clusters like EKS, we need another solution. And it should also be available as "one-liner" just as a kubectl wait would be.
A good starting point could be this superuser answer about "watching" the output of a command until a particular string is observed and then exit:
until my_cmd | grep "String Im Looking For"; do : ; done
If we use this approach together with a kubectl get we can craft a command which will wait until the field ingress gets populated into the status.loadBalancer field in our Service:
until kubectl get service/tekton-dashboard-external-svc-manual -n tekton-pipelines --output=jsonpath='{.status.loadBalancer}' | grep "ingress"; do : ; done
This will wait until the ingress field got populated and then print out the AWS ELB address (e.g. via using kubectl get service tekton-dashboard-external-svc-manual -n tekton-pipelines --output=jsonpath='{.status.loadBalancer.ingress[0].hostname}' thereafter):
$ until kubectl get service/tekton-dashboard-external-svc-manual -n tekton-pipelines --output=jsonpath='{.status.loadBalancer}' | grep "ingress"; do : ; done
{"ingress":[{"hostname":"a74b078064c7d4ba1b89bf4e92586af0-18561896.eu-central-1.elb.amazonaws.com"}]}
Now we have a one-liner command that behaves just like a kubectl wait for our Service to become available through the AWS Loadbalancer. We can double check if this is working with the following commands combined (be sure to delete the Service using kubectl delete service/tekton-dashboard-external-svc-manual -n tekton-pipelines before you execute it, because otherwise the Service incl. the AWS LoadBalancer already exists):
kubectl apply -f tekton-dashboard-service.yml -n tekton-pipelines && \
until kubectl get service/tekton-dashboard-external-svc-manual -n tekton-pipelines --output=jsonpath='{.status.loadBalancer}' | grep "ingress"; do : ; done && \
kubectl get service tekton-dashboard-external-svc-manual -n tekton-pipelines --output=jsonpath='{.status.loadBalancer.ingress[0].hostname}'
Here's also a full GitHub Actions pipeline run if you're interested.
I am trying to deploy the aws-load-balancer-controller on my Kubernetes cluster on AWS = by following the steps given in https://docs.aws.amazon.com/eks/latest/userguide/aws-load-balancer-controller.html
After the yaml file is applied and while trying to check the status of the deployment , I get :
$ kubectl get deployment -n kube-system aws-load-balancer-controller
NAME READY UP-TO-DATE AVAILABLE AGE
aws-load-balancer-controller 0/1 1 0 6m39s
I tried to debug it and I got this :
$ kubectl logs -n kube-system deployment.apps/aws-load-balancer-controller
{"level":"info","logger":"controller-runtime.metrics","msg":"metrics server is starting to listen","addr":":8080"}
{"level":"error","logger":"setup","msg":"unable to create controller","controller":"Ingress","error":"the server could not find the requested resource"}
The yaml file is pulled directly from https://github.com/kubernetes-sigs/aws-load-balancer-controller/releases/download/v2.3.0/v2_3_0_full.yaml and apart from changing the Kubernetes cluster name, no other modifications are done.
Please let me know if I am missing some step in the configuration.
Any help would be highly appreciated.
I am not sure if this helps, but for me the issue was that the version of the aws-load-balancer-controller was not compatible with the version of Kubernetes.
aws-load-balancer-controller = v2.3.1
Kubernetes/EKS = 1.22
Github issue for more information:
https://github.com/kubernetes-sigs/aws-load-balancer-controller/issues/2495
I am not exactly sure what's going on which is why I am asking this question. When I run this command:
kubectl config get-clusters
I get:
arn:aws:eks:us-west-2:91xxxxx371:cluster/eks-cluster-1
arn:aws:eks:us-west-2:91xxxxx371:cluster/eks1
then I run:
kubectl config current-context
and I get:
arn:aws:eks:us-west-2:91xxxxx371:cluster/eks-cluster-1
and if I run kubectl get pods, I get the expected output.
But how do I switch to the other cluster/context? what's the difference between the cluster and context? I can't figure out how these commands differ:
When I run them, I still get the pods from the wrong cluster:
root#4c2ab870baaf:/# kubectl config set-context arn:aws:eks:us-west-2:913617820371:cluster/eks1
Context "arn:aws:eks:us-west-2:913617820371:cluster/eks1" modified.
root#4c2ab870baaf:/#
root#4c2ab870baaf:/# kubectl get pods
NAME READY STATUS RESTARTS AGE
apache-spike-579598949b-5bjjs 1/1 Running 0 14d
apache-spike-579598949b-957gv 1/1 Running 0 14d
apache-spike-579598949b-k49hf 1/1 Running 0 14d
root#4c2ab870baaf:/# kubectl config set-cluster arn:aws:eks:us-west-2:91xxxxxx371:cluster/eks1
Cluster "arn:aws:eks:us-west-2:91xxxxx371:cluster/eks1" set.
root#4c2ab870baaf:/# kubectl get pods
NAME READY STATUS RESTARTS AGE
apache-spike-579598949b-5bjjs 1/1 Running 0 14d
apache-spike-579598949b-957gv 1/1 Running 0 14d
apache-spike-579598949b-k49hf 1/1 Running 0 14d
so I really don't know how to properly switch between clusters or contexts and also switch the auth routine when doing so.
For example:
contexts:
- context:
cluster: arn:aws:eks:us-west-2:91xxxxx371:cluster/ignitecluster
user: arn:aws:eks:us-west-2:91xxxx371:cluster/ignitecluster
name: arn:aws:eks:us-west-2:91xxxxx371:cluster/ignitecluster
- context:
cluster: arn:aws:eks:us-west-2:91xxxx371:cluster/teros-eks-cluster
user: arn:aws:eks:us-west-2:91xxxxx371:cluster/teros-eks-cluster
name: arn:aws:eks:us-west-2:91xxxxx371:cluster/teros-eks-cluster
To clarify on the difference between set-context and use-context
A context is a group of access parameters. Each context contains a Kubernetes cluster, a user, and a namespace. So when you do set-context, you just adding context details to your configuration file ~/.kube/config, but it doesn't switch you to that context, while use-context actually does.
Thus, as Vasily mentioned, in order to switch between clusters run
kubectl config use-context <CONTEXT-NAME>
Also, if you run kubectl config get-contexts you will see list of contexts with indication of the current one.
Use
kubectl config use-context arn:aws:eks:us-west-2:91xxxxx371:cluster/eks-cluster-1
and
kubectl config use-context arn:aws:eks:us-west-2:91xxxxx371:cluster/eks
Consider using kubectx for managing your contexts.
Usage
View all contexts (the current context is bolded):
$kubectx
arn:aws:eks:us-east-1:12234567:cluster/eks_app
->gke_my_second_cluster
my-rnd
my-prod
Switch to other context:
$ kubectx my-rnd
Switched to context "my-rnd".
Bonus:
In the same link - check also the kubens tool.
This is the best command to switch between different EKS clusters.
I use it every day.
aws eks update-kubeconfig --name example
Documentation:
https://docs.aws.amazon.com/cli/latest/reference/eks/update-kubeconfig.html
Trying to update a multi-container pods with
kubectl rolling-update my_rc --image=eu.gcr.io/project_id/myimage
I got:
error: Image update is not supported for multi-container pods
What is the way to update a single container or I must delete and recreate the pod ?
For now, your best option is to update the yaml file defining the replication controller to use the new image and run:
kubectl rolling-update my_rc -f my_file.yaml
If you don't have a yaml file defining your replication controller, you can get one by running:
kubectl get rc my_rc --output=yaml > my_file.yaml
You should then be able to update the image specified in that file and run the rolling-update.
In the next release of Kubernetes (targeted for March), you'll be able to just pass the --container flag to tell kubectl which of the containers in the pod should use the new image:
kubectl rolling-update my_rc --container=my_container --image=eu.gcr.io/project_id/myimage
This feature was added by a community member after version 1.1 was cut.
Background
We're using Jenkins to deploy a new version of a Kubernetes (k8s) replication controller to our test or prod cluster. The test and prod (k8s) clusters are located under different (google cloud platform) projects. We have configured two profiles for our gcloud SDK on Jenkins, one for test (test-profile) and one for prod (prod-profile). We have defined a managed script in Jenkins that performs the rolling update for our replication controller. The problems is that I cannot find a way to control to which project I want to target the kubectl rolling-update command (you can specify which cluster but not which project afict). So right now our script that does the rolling update to our test server looks something like this:
gcloud config configurations activate test-profile && kubectl rolling-update ...
While this works it could be extremely dangerous if two jobs run concurrently for different environments. Say that job 1 targets the test environment and job 2 targets prod. If job2 switches the active profile to "prod-profile" before job 1 has executed its rolling-update command job 1 will target to wrong project and in worse case update the wrong replication controller (if the clusters have the same name).
Question
Is there a way to specify which project that a kubectl command is targeting (for example during a rolling update) that is safe to run concurrently?
You can pass the --cluster= or --context= flags to kubectl to set a single run. For example, if I have two clusters in my ~/.kube/config "foo" and "bar":
$ kubectl --cluster=foo get pods
NAME READY STATUS RESTARTS AGE
foo-ht1qh 1/1 Running 0 3h
foo-wf8f4 1/1 Running 0 3h
foo-yvgpd 1/1 Running 0 3h
vs
$ kubectl --cluster=bar get pods
NAME READY STATUS RESTARTS AGE
bar-de4h7 1/1 Running 0 9h
bar-c4g03 1/1 Running 0 9h
bar-2sprd 1/1 Running 0 9h
You may use gcloud config set project yourProject to set the project property. See https://cloud.google.com/sdk/gcloud/reference/config/set