I am following a tutorial, where a pod is created using the below command:
kubectl run firstPod --image={image from dockerhub repository}
But I am getting the following error:
Error from server (Forbidden): pods "firstPod" is forbidden: error looking up service account default/default: serviceaccount "default" not found
The goal of command is to pull docker image from my own repository and use it to create pod. I saw already some solutions that use .yaml file (but I didn't like the answer). All I want is to run this command. I am using windows 10 and docker desktop for a kubernetes cluster (minikube etc.).
You can test it with network-multitool. It will keep on running a webserver and have a lot of great tools.
kubectl run multitool --image=praqma/network-multitool --replicas=1
If that works, find the podname
kubectl get pods
Then you can exec into it with the name you found above
kubectl exec -it multitool-3822887632-pwlr1 bash
From inside the container/pod you can tjek that the webserver is running by
curl localhost
If the first command doesnt work, then something is wrong.
Check if the service account exists
kubectl get sa
Thanks for answers. Now I realize, that I forget to start my local cluster minikube.
minikube start
Now it is ok to create a pod.
Related
I am using Rancher 2.X. I have installed it on my local machine. I have also installed a local Kubernetes cluster using Minikube. When I try to create a cluster in Rancher UI and import the existing K8s cluster, I am asked to run the following command on my K8s cluster using kubectl:
kubectl apply -f https://10.41.124.40/v3/import/g2gk5ntvnlh8xtvlngjmxdt22cm6zgtfjhswgcqmhltpg9nt9pvgsc.yaml
But, when I run this command, I get this error:
error: SchemaError(io.k8s.api.core.v1.ComponentCondition): invalid object doesn’t have additional properties
What am I doing wrong?
Thanks!!!
Let try with this:
curl -sKL https://10.41.124.40:8443/v3/import/g2gk5ntvnlh8xtvlngjmxdt22cm6zgtfjhswgcqmhltpg9nt9pvgsc.yaml > /tmp/cluster.yaml && kubectl apply -f /tmp/cluster.yaml
I have configured a secret on Kubernetes and inside the node, I am able to pull an image with docker pull perfectly. But when kubectl tries to schedule a pod on the node it shows image pull backoff error. Is there any setting needs to be done while bootstrapping. I am using community AMI on AWS for Kubernetes node.
Try this:
kubectl describe pod-name - see event log at the end. it should show series of events starting from initial image pull to subsequent attempts and may continue to restart in order to achieve desired state as per deployment record
In most scenarios something within container erroring out resulting restart expected behavior by k8s. to check logs - kubectl logs pod-name
Try to keep container running so you can peek inside running container for more troubleshooting using kubectl exec -it pod-name (if single container) or kubectl exec -it pod-name -c container-name.
I have been trying to run tomcat container on port 5000 on cluster using kubernetes. But when i am using kubectl create -f tmocat_pod.yaml , it creates pod but docker ps does not give any output. Why is it so?
Ideally, when it is running a pod, it means it is running a container inside that pod and that container is defined in yaml file.
Why is that docker ps does not show any containers running?
I am following the below URLs:
http://containertutorials.com/get_started_kubernetes/k8s_example.html
https://blog.jetstack.io/blog/k8s-getting-started-part2/
How can I get it running and see tomcat running on browser on port 5000.
The docker containers should be running on the virtual machine. Since I only installed minikube on my local machine, I confirmed the following will bring what you want:
minikub ssh
...
docker ps
Just try the kubernetes equivalent of minikube ssh.
In Kubernetes, Docker contaienrs are run on Pods, and Pods are run on Nodes, and Nodes are run on your machine (minikube/GKE)
When you run kubectl create -f tmocat_pod.yaml you basically create a pod and it runs the docker container on that pod.
The node that holds this pod, is basically a virtual instance, if you could 'SSH' into that node, docker ps would work.
What you need is:
kubectl get pods <-- It is like docker ps, it shows you all the pods (think of it as docker containers) running
kubectl get nodes <-- view the host machines for your pods.
kubectl describe pods <pod-name> <-- view system logs for your pods.
kubectl logs <pod-name> <-- Will give you logs for the specific pod.
You can connect your Terminal with the docker server what is running inside your Node/VM.
With this command in your terminal: eval $(minikube docker-env)
This only configures your current terminal window.
illustration
may be you are not using docker as container runtime.
I faced the same issue, and i forgot that i switched to gVisor with runsc as handler.
cat /etc/default/kubelet
KUBELET_EXTRA_ARGS="--container-runtime remote --container-runtime-endpoint unix:///run/containerd/containerd.sock"
If so, you need to use runsc command instead of docker.
I'm not sure where you are running the docker ps command, but if you are trying to do that from your host machine and the k8s cluster is located elsewhere, i.e. your machine is not a node in the cluster, docker ps will not return anything since the containers are not tied to your docker host.
Assuming your pod is running, kubectl get pods will display all of your running pods. To check further details, you can use kubectl describe pod <yourpodname> to check the status of each container (in great detail). To get the pod names, you should be able to use tab-complete with the kubernetes cli. Also, if your pod contains multiple containers, you will need to give the container name as well, which you can use tab-complete for after you've selected your pod.
The output will look similar to:
kubectl describe pod comparison-api-dply-reborn-6ffb88b46b-s2mtx
Name: comparison-api-dply-reborn-6ffb88b46b-s2mtx
Namespace: default
Node: aks-nodepool1-99697518-0/10.240.0.5
Start Time: Fri, 20 Apr 2018 14:08:21 -0400
Labels: app=comparison-pod-reborn
pod-template-hash=2996446026
...
Status: Running
IP: *.*.*.*
Controlled By: ReplicaSet/comparison-api-dply-reborn-6ffb88b46b
Containers:
rabbit-mq:
...
Port: 5672/TCP
State: Running
...
If your containers and pods are already running, then you shouldn't need to troubleshoot them too much. To make them accessible from the Public Internet, take a look at Services (https://kubernetes.io/docs/concepts/services-networking/service/) to make your API's IP address fixed and easily reachable.
Have you tried a "docker ps -a" to see if the container is dead? If it is there you can see its logs with "docker logs " and maybe this gives you a hint.
If your pod is running successfully and if you are looking for the container on the node where the pod is scheduled the issue could be kubernetes is using a different container runtime.
Example
root#renjith-laptop:/home/renjith/raspbery-k8s# kubectl exec -it nginx-8586cf59-h92ct bash
root#nginx-8586cf59-h92ct:/# exit
exit
root#renjith-laptop:/home/renjith/raspbery-k8s# kubectl get po -o wide
NAME READY STATUS RESTARTS AGE IP NODE
nginx-8586cf59-h92ct 1/1 Running 0 47s 10.20.0.3 renjith-laptop
root#renjith-laptop:/home/renjith/raspbery-k8s# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
root#renjith-laptop:/home/renjith/raspbery-k8s#
Here I am able exec to the pod, and I am in the same node where pod is scheduled, but docker ps doesn't show the container. In my case kubelet is using different container runtime, one of the argument to kubelet service is --container-runtime-endpoint=unix:///var/run/cri-containerd.sock
From Kubernetes documentation to get container images running on your system:
kubectl get pods --all-namespaces -o jsonpath="{.items[*].spec.containers[*].image}" |\
tr -s '[[:space:]]' '\n' |\
sort |\
uniq -c
Then you get back something like:
2 registry.k8s.io/coredns/coredns:v1.9.3
1 registry.k8s.io/etcd:3.5.4-0
1 registry.k8s.io/kube-apiserver:v1.25.1
1 registry.k8s.io/kube-controller-manager:v1.25.1
3 registry.k8s.io/kube-proxy:v1.25.1
1 registry.k8s.io/kube-scheduler:v1.25.1
Let's say I have a docker image created using a Dockerfile. At the time of writing the Dockerfile I had to test it repeatedly to realize what I did wrong. To debug a docker image I can simply run a test container and look at its stdout/stderr to see what's wrong with the image.
IMAGE_NAME=authoritative-dns-bind
IMAGE_OPTIONS="
-v $(pwd)/config.yaml:/config.yaml:ro
-p 127.0.0.1:53:53
-p 127.0.0.1:53:53/udp"
docker run -t -i $IMAGE_OPTIONS $IMAGE_NAME
Learning the above was good enough to iteratively create and debug a minimal working Docker container. Now I'm looking for a way to do the same for OpenShift.
I'm pretty much aware of the fact that the container is not ready for OpenShift. My plan is to run it and watch its stdoud/stderr like I did with Docker. One of the people I asked for help came up with a command that looked like exactly what I need.
oc run -i -t --image $IMAGE_NAME --command test-pod -- bash
And the above command seemed for me for fedora:24 and fedora:latest images from the docker registry and I got a working shell. But the same wouldn't happen for my derived image with a containerized service. My explanation is that it probably does an entirely different thing and instead of starting the command interactively it starts it non-interactively and then tries to run bash inside a failed container.
So what I'm looking for is a reasonable way to debug a container image in OpenShift. I expected that I would be able to at least capture and view stdin/stdout of OpenShift containers.
Any ideas?
Update
According to the comment by Graham oc run should indeed work as docker run but it doesn't seem to be the case. With original Fedora images the bash always appears at least upon hitting enter.
# oc run -i -t --image authoritative-dns-bind --command test-auth13 -- bash
Waiting for pod myproject/test-auth13-1-lyng3 to be running, status is Pending, pod ready: false
Waiting for pod myproject/test-auth13-1-lyng3 to be running, status is Pending, pod ready: false
Waiting for pod myproject/test-auth13-1-lyng3 to be running, status is Pending, pod ready: false
...
Waiting for pod myproject/test-auth13-1-lyng3 to be running, status is Pending, pod ready: false
^C
#
I wasn't able to try out the suggested oc debug yet as it seems to require more configuration than just simple image. There's another problem with oc run as that command creates new and new containers that I don't really need. I hope there is a way to start the debug easily and get the container automatically distroyed afterwards.
There are three main commands to debug pods:
oc describe pod $pod-name -- detailed info about the pod
oc logs $pod-name -- stdout and stderr of the pod
oc exec -ti $pod-name -- bash -- get a shell in running pod
To your specific problem: oc run default pull policy is set to Always. This means that OpenShift will try to pull the image until successful and refuse to use the local one.
Once this kuberenetes patch lands in OpenShift origin, the pull policy will be easily configurable.
Please do not consider this a final answer to the question and supersede it with your own better answers...
I'm now using a pod configuration file like the following...
apiVersion: v1
kind: Pod
metadata:
name: "authoritative-dns-server" # pod name, your reference from command line
namespace: "myproject" # default namespace in `oc cluster up`
spec:
containers:
- command:
- "bash"
image: "authoritative-dns-bind" # use your image!
name: "authoritative-dns-bind-container" # required
imagePullPolicy: "Never" # important! you want openshift to use your local image
stdin: true
tty: true
restartPolicy: "Never"
Note the command is explicitly set to bash. You can then create the pod, attach to the container and run the docker command yourself.
oc create -f pod.yaml
oc attach -t -i authoritative-dns-server
/files/run-bind.py
This looks far from ideal and it doesn't really help you debug an ordinary openshift container with standard pod configuration, but at least it's possible to debug, now. Looking forward to better answers.
I have the following questions:
I am logged into a Kubernetes pod using the following command:
./cluster/kubectl.sh exec my-nginx-0onux -c my-nginx -it bash
The 'ip addr show' command shows its assigned the ip of the pod. Since pod is a logical concept, I am assuming I am logged into a docker container and not a pod, In which case, the pod IP is same as docker container IP. Is that understanding correct?
from a Kubernetes node, I do sudo docker ps and then do the following:-
sudo docker exec 71721cb14283 -it '/bin/bash'
This doesn't work. Does someone know what I am doing wrong?
I want to access the nginx service I created, from within the pod using curl. How can I install curl within this pod or container to access the service from inside. I want to do this to understand the network connectivity.
Here is how you get a curl command line within a kubernetes network to test and explore your internal REST endpoints.
To get a prompt of a busybox running inside the network, execute the following command. (A tip is to use one unique container per developer.)
kubectl run curl-<YOUR NAME> --image=radial/busyboxplus:curl -i --tty --rm
You may omit the --rm and keep the instance running for later re-usage. To reuse it later, type:
kubectl attach <POD ID> -c curl-<YOUR NAME> -i -t
Using the command kubectl get pods you can see all running POD's. The <POD ID> is something similar to curl-yourname-944940652-fvj28.
EDIT: Note that you need to login to google cloud from your terminal (once) before you can do this! Here is an example, make sure to put in your zone, cluster and project:
gcloud container clusters get-credentials example-cluster --zone europe-west1-c --project example-148812
The idea of Kubernetes is that pods are assigned on a host but there is nothing sure or permanent, so you should NOT try to look up the IP of a container or pod from your container, but rather use what Kubernetes calls a Service.
A Kubernetes Service is a path to a pod with a defined set of selectors, through the kube-proxy, which will load balance the request to all pods with the given selectors.
In short:
create a Pod with a label called 'name' for example. let's say name=mypod
create a Service with the selector name=mypod that you call myService for example, to which you assign the port 9000 for example.
then you can curl from a pod to the pods served by this Service using
curl http://myService:9000
This is assuming you have the DNS pod running of course.
If you ask for a LoadBalancer type of Service when creating it, and run on AWS or GKE, this service will also be available from outside your cluster. For internal only service, just set the flag clusterIP: None and it will not be load balanced on the outside.
see reference here:
https://kubernetes.io/docs/concepts/services-networking/service/
https://kubernetes.io/docs/tutorials/services/
Kubernetes uses the IP-per-pod model. All containers in the same pod share the same IP address as if they are running on the same host.
The command should follow docker exec [OPTIONS] CONTAINER COMMAND [ARG...]. In your case, sudo docker exec -it 71721cb14283 '/bin/bash' should work. If not, you should provide the output of your command.
It depends on what image you use. There is nothing special about installing a software in a container. For nginx, try apt-get update && apt-get install curl
There's an official curl team image these days:
https://hub.docker.com/r/curlimages/curl
Run it with:
kubectl run -it --rm --image=curlimages/curl curly -- sh