I use kubespray installed Kubernetes Cluster. I defined the cluster name as cluster.devops in the file, group_vars/k8s-cluster/k8s-cluster.yml. After the Kubernetes Cluster installed. the current-context in kube confi file is kubernetes-admin#cluster.devops. I would like the current-context is cluster.devops,
i.e. current-context is same as cluster name. How to do it?
you can rename context using
kubectl config rename-context old-name new-name
for example in your case
kubectl config rename-context kubernetes-admin#cluster.devops cluster.devops
Related
I've used the helm chart to deploy Spark to Kubernetes in GCE. According to default configuration in values.yaml the Spark is deployed to the path /opt/spark. I've checked that Spark has deployed successfully by running kubectl --namespace=my-namespace get pods -l "release=spark". There is 1 master and 3 workers running.
However when I've tried to check Spark version by executing spark-submit --version from the Google cloud console it returned -bash: spark-submit: command not found.
I've navigated to the /opt directory and the /spark folder is missing. What should I do to be able to open Spark shell Terminal and to execute Spark commands?
You can verify by checking service
kubectl get services -n <namespace>
you can port-forward particular service and try running locally to check
kubectl port-forward svc/<service name> <external port>:<internal port or spark running port>
Locally you can try running spark terminal it will be connected to spark running on GCE instance.
If you check the helm chart document there is also options for UI you can also do same to access UI via port-forward
Access via SSH inside pod
Kubectl exec -it <spark pod name> -- /bin/bash
here you can directly run spark commands. spark-submit --version
Access UI
Access UI via port-forwarding if you have enable UI in helm chart.
kubectl port-forward svc/<spark service name> <external port>:<internal port or spark running port>
External Load balancer
This particular helm chart also creating External Load balancer you can also get External IP using
Kubectl get svc -n <namespace>
Access Shell
If want to connect via LB IP & port
./bin/spark-shell --conf spark.cassandra.connection.host=<Load balancer IP> spark.cassandra-connection.native.port=<Port>
Creating connection using port-forward
kubectl port-forward svc/<spark service name> <external(local) port>:<internal port or spark running port>
./bin/spark-shell --conf spark.cassandra.connection.host=localhost spark.cassandra-connection.native.port=<local Port>
One way would be login to pod and then run Spark commands
List the pod
kubectl --namespace=my-namespace get pods -l "release=spark"
Now, Login to the pod using following command:
kubectl exec -it <pod-id> /bin/bash
Now, you should be inside the pod and can run spark commands
spark-submit --version
Ref: https://kubernetes.io/docs/tasks/debug-application-cluster/get-shell-running-container/#getting-a-shell-to-a-container
Hope this helps.
This worked for me.
spark-shell --master k8s://localhost:32217
My spark master is a LoadBalancer exposed at localhost:32217
I cannot access my Cassandra database, deployed on the same namespace in kubernetes.
My service has no cluster IP but an internal endpoint cassandra.hosting:9042 but whenever I try to connect from an internal spring application using
spring.data.cassandra.contact-points=cassandra.hosting
it fails with the error All host(s) tried for query failed
How did you configure your endpoint? Generally, all services and pods in a Kubernetes cluster are discoverable through a standard DNS notation. It looks like this:
<service-name>.<namespace>.svc.cluster.local # or
<pod-name>.<namespace>.svc.cluster.local # or
<pod-name>.<subdomain>.<namespace>.svc.cluster.local
If you are within the same namespace this would work too:
<service-name>
<pod-name>
<pod-name>.<subdomain>
I would also check either core-dns or kube-dns are running and ready:
kubectl -n kube-system get pods | grep dns
How I can setup and securely access a kubernetes cluster on EC2 instance from my laptop? I want it to be a single-node cluster, like running only one instance. Have tried run minikube at EC2 instance, but can't config laptop to connect to it.
So, in the result, I want to run like 10 services/pods in EC2 instance and just debug run on my dev laptop.
Thanks!
You can use KOPS (Kubernetes Ops) to Accomplish this. Its a really handy tool. There's a whole section for configuring a cluster on AWS. I use it on a couple of projects and id really recommend it. Its an easy to understand setup and straight forward.
After the cluster is up you can use kubectl proxy to proxy locally and interact with the cluster. Or use kubectl with config files to set up services and pods.
It does not create a new instance per service or pod it creates a pod on the node(s) that is already existing on the cluster.
In your case you could have a single master and a single node in whatever size that suits your needs.t.2 micro or otherwise
A command to accomplish that would look like:
kops create cluster \
--cloud aws \
--state $KOPS_STATE_STORE \
--node-count $NODE_COUNT \
--zones $ZONES \
--master-zones $MASTER_ZONES \
--node-size $NODE_SIZE \
--master-size $MASTER_SIZE \
-v $V_LOG_LEVEL \
--ssh-public-key $SSH_KEY_PATH \
--name=$CLUSTER_NAME
Where the $NODE_COUNT would be 1 thus having a single Node or EC2 Instance and another instance as the master
To connect to it locally you can also deploy the kubernetes dashboard on your cluster.
kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/recommended/kubernetes-dashboard.yaml
To access Dashboard from your local workstation you must create a secure channel to your Kubernetes cluster. Run the following command:
kubectl proxy
Now you can access the Dashboard at:
http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/
I have two-node cluster on one machine and one config file (elasticsearch.yml). Is it possible to create another .yml-config file and start every instance with different config-file? For example, i want run cluster on two ports (localhost:9200 and localhost:9201) on the same time.
I can't find command-line API for starting elastic-cluster (config-file as an argument?).
You should be able to start your second ES instance with the -Epath.conf setting on the command line and point to another folder where you have your second elasticsearch.yml configuration file
./bin/elasticsearch -Epath.conf=/path/to/my/second/config/
A newer approach starting from ES 6 release for launching multiple instances based on the same ES installation is to have multiple config folders and declaring path variable before startup execution
ES_PATH_CONF=/apps/my-es/conf/node-1 ./elasticsearch
ES_PATH_CONF=/apps/my-es/conf/node-2 ./elasticsearch
To launch as daemon include -d and -p <pidName> for defining pid name
ES_PATH_CONF=/apps/my-es/conf/node-1 ./elasticsearch -d -p es_node1_pid
ES_PATH_CONF=/apps/my-es/conf/node-2 ./elasticsearch -d -p es_node2_pid
here is a reference on ES docs:
https://www.elastic.co/guide/en/elasticsearch/reference/current/settings.html
it has to be more than command line.You should look at installing two instance of elasticsearch service configured to listen at two different ports.
If you are on ubuntu OS -
you can have two init.d scripts for both two instances
1)In the init.d script set the name of the process that run the service like for two cluster set elasticsearch_node_1 and elasticsearch_node_2
2)In the same file configure the path to logs, data and configuration file to two seperate locations for both the init files.
untill here you will have two services running on the same machine
Maybe you don't want to run the instances as OS service then i recommend checking this link
Two nodes on same machine
$ bin/elasticsearch -Des.config=$ES_HOME/config/elasticsearch.1.yml
$ bin/elasticsearch -Des.config=$ES_HOME/config/elasticsearch.2.yml
3)now modify the elasticsearch.yml files for each instance pointed by init script.
change http.port to any port you want to run your instance on.
for discovery host1 and host2 will be same, only you have to change port to another node for each instance and accordingly set path.data and path.logs for each instance
http.port: 9200
discovery.zen.ping.unicast.hosts: ["host1", "host2:port"]
path.data: /path/to/data
path.logs: /path/to/logs
Background
CoreOS-Kubernetes has a project for multi-node on Vagrant:
https://github.com/coreos/coreos-kubernetes
https://coreos.com/kubernetes/docs/latest/kubernetes-on-vagrant.html
They have a custom cloud config for the etcd node, but none for the worker node. For those, the Vagrant file references shell scripts, which contain some cloud config but mostly Kubernetes yaml:
https://github.com/coreos/coreos-kubernetes/blob/master/multi-node/generic/worker-install.sh
Objective
I'm trying to mount a NFS directory onto the coreOS worker nodes, for use in a Kubernetes pod. From what I read about Kubernetes in docs and tutorials, I want to mount on the node first as a persistent volume, like this on docker:
http://www.emergingafrican.com/2015/02/enabling-docker-volumes-and-kubernetes.html
I saw some posts that said mounting in the pod itself can be buggy, and want to avoid it by mounting on coreOS worker node first:
Kubernetes NFS volume mount fail with exit status 32
If mounting right in the pod is the standard way, just let me know and I'll do that.
Question
Are there options for customizing the cloud config for the worker node? I'm about to start hacking on that shell script, but thought I should check first. I looked through the docs but couldn't find any.
This is the coreOS cloud config I'm trying to add to the Vagrant file:
https://coreos.com/os/docs/latest/mounting-storage.html#mounting-nfs-exports
No NFS mount on coreOS is needed. Kubernetes will do it for you right in the pod:
http://kubernetes.io/v1.1/examples/nfs/README.html
Checkout nfs-busybox replication controller:
http://kubernetes.io/v1.1/examples/nfs/nfs-busybox-rc.yaml
I ran this and got it to write files to the server. That helped me debug the application. Note that even though nfs mounts do not show up when you ssh into the kubernetes node and run docker -it run /bin/bash, they are mounted in the kubernetes pod.. That's where most of my misunderstanding occurred. I guess you have to add the mount parameters to the command when doing it manually.
Additionally, my application, gogs, stored it's config files in /data . To get it to work, I first mounted the nfs to /mnt. Then, like in the kubernetes nfs-busybox example, I created a command which would copy all folders in /data to /mnt . In the replication controller yaml, under the container node, I put a command:
command:
- sh
- -c
- 'sleep 300; cp -a /data /mnt; done'
This gave me enough time to run the initial config of my app. Then I just waited until the sleep time was up and the files were copied over.
I then change my mount point to /data, and now the app starts right where it left off when pod restarts. Coupled with external mysql server, and it so far it looks like it's stateless.