Getting Started¶
Installation¶
Ubuntu¶
- Switch to root user
$ sudo -s [sudo] password for your_user:
- Install pre-requisite software packages
$ apt-get update $ apt-get install ssh $ apt-get install docker.io $ apt-get install curl
- Password-less ssh login setup, accept all the default parameters in the prompt of the below command (required for Kubernetes installation)
$ ssh-keygen -t rsa Generating public/private rsa key pair. Enter file in which to save the key (/root/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /root/.ssh/id_rsa. Your public key has been saved in /root/.ssh/id_rsa.pub. The key fingerprint is: e1:c9:a5:dd:80:ee:cd:f0:c8:11:6c:a5:d4:ba:ff:cc root@vkohli-Latitude-E7440 The key's randomart image is: +--[ RSA 2048]----+ | ... | | + o. | | o B. | | + B..+ | | S o.. | | . *.. | | . *. | | . .o | | .E | +-----------------+
- Copy the ssh id_rsa key locally
$ ssh-copy-id -i /root/.ssh/id_rsa.pub 127.0.0.1In case this command fails please use this alternative solution in order to add the key
$ cat /root/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys
- Validate the password-less ssh-login
$ ssh root@127.0.0.1 root@vkohli-virtual-machine:~$ exit logout Connection to 127.0.0.1 closed
- Get the Kubernetes release bundle from the official github repository
$ wget https://github.com/GoogleCloudPlatform/kubernetes/releases/download/v1.0.1/kubernetes.tar.gz
- Untar the Kubernetes bundle in the same directory
$ tar -xvf kubernetes.tar.gz
- We will build the binaries of Kubernetes code specifically for ubuntu cluster
$ cd kubernetes/cluster/ubuntuExecute the following shell script
$ ./build.sh Download flannel release ... Flannel version is 0.4.0 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 411 0 411 0 0 252 0 --:--:-- 0:00:01 --:--:-- 252 100 2393k 100 2393k 0 0 204k 0 0:00:11 0:00:11 --:--:-- 388k Download etcd release ... % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 410 0 410 0 0 272 0 --:--:-- 0:00:01 --:--:-- 272 100 3713k 100 3713k 0 0 286k 0 0:00:12 0:00:12 --:--:-- 496k Download kubernetes release ... % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 396 0 396 0 0 279 0 --:--:-- 0:00:01 --:--:-- 279 100 97.8M 100 97.8M 0 0 715k 0 0:02:20 0:02:20 --:--:-- 501k ~/kubernetes/cluster/ubuntu/kubernetes/server ~/kubernetes/cluster/ubuntu ~/kubernetes/cluster/ubuntu Done! All your commands locate in ./binaries dirThis shell script will download and build the latest version of K8s, etcd and flannel binaries which can be found at following location;
$ cd binaries $ ls kubectl master minion
kubectlbinary controls the Kubernetes cluster manager and the folder master & minion contains the binaries built for the purpose of configuring K8s master and node respectively.
- Configure the cluster information by editing only the following parameters of the file
cluster/ubuntu/config-default.shin the editor of your choice.
$ cd $ vi kubernetes/cluster/ubuntu/config-default.sh export nodes="root@127.0.0.1" export roles="ai" export NUM_MINIONS=${NUM_MINIONS:-1}Only update the above mentioned information in the file, rest of the configuration will remain as it is. The first variable nodes defines all the cluster nodes, in our case same machine will be configured as master and node so it contains only one entry.The role below “ai” specifies that same machine will act as master, “a” stands for master and “i” stands for node.
- Now, we will be starting the cluster with the following command;
$ cd kubernetes/cluster $ KUBERNETES_PROVIDER=ubuntu ./kube-up.sh Starting cluster using provider: ubuntu ... calling verify-prereqs ... calling kube-up FLANNEL_NET 172.16.0.0/16 Deploying master and minion on machine 127.0.0.1 config-default.sh 100% 2904 2.8KB/s 00:00 util.sh 100% 13KB 13.4KB/s 00:00 flanneld.conf 100% 569 0.6KB/s 00:00 kube-controller-manager.conf 100% 746 0.7KB/s 00:00 kube-apiserver.conf 100% 676 0.7KB/s 00:00 etcd.conf 100% 576 0.6KB/s 00:00 kube-scheduler.conf 100% 676 0.7KB/s 00:00 kube-apiserver 100% 2358 2.3KB/s 00:00 kube-controller-manager 100% 2672 2.6KB/s 00:00 etcd 100% 2073 2.0KB/s 00:00 flanneld 100% 2159 2.1KB/s 00:00 kube-scheduler 100% 2360 2.3KB/s 00:00 reconfDocker.sh 100% 1493 1.5KB/s 00:00 kube-proxy.conf 100% 648 0.6KB/s 00:00 flanneld.conf 100% 569 0.6KB/s 00:00 kubelet.conf 100% 634 0.6KB/s 00:00 etcd.conf 100% 576 0.6KB/s 00:00 kube-proxy 100% 2230 2.2KB/s 00:00 etcd 100% 2073 2.0KB/s 00:00 flanneld 100% 2159 2.1KB/s 00:00 kubelet 100% 2162 2.1KB/s 00:00 kube-apiserver 100% 34MB 33.7MB/s 00:00 kube-controller-manager 100% 26MB 26.2MB/s 00:00 etcdctl 100% 6041KB 5.9MB/s 00:00 etcd 100% 6494KB 6.3MB/s 00:00 flanneld 100% 8695KB 8.5MB/s 00:00 kube-scheduler 100% 17MB 17.0MB/s 00:00 kube-proxy 100% 17MB 16.8MB/s 00:00 etcdctl 100% 6041KB 5.9MB/s 00:00 etcd 100% 6494KB 6.3MB/s 00:00 flanneld 100% 8695KB 8.5MB/s 00:00 kubelet 100% 33MB 33.2MB/s 00:01 [sudo] password to copy files and start node: etcd start/running, process 1125 Connection to 127.0.0.1 closed. Validating master Validating root@127.0.0.1 Kubernetes cluster is running. The master is running at: http://127.0.0.1 FLANNEL_NET 172.16.0.0/16 Using master 127.0.0.1 Wrote config for ubuntu to /home/root/.kube/config ... calling validate-cluster Waiting for 1 ready nodes. 0 ready nodes, 0 registered. Retrying. Found 1 nodes. NAME LABELS STATUS 1 127.0.0.1 kubernetes.io/hostname=127.0.0.1 Ready Validate output: NAME STATUS MESSAGE ERROR scheduler Healthy ok nil etcd-0 Healthy {"action":"get","node":{"dir":true,"nodes":[{"key":"/registry","dir":true,"modifiedIndex":3,"createdIndex":3},{"key":"/coreos.com","dir":true,"modifiedIndex":16,"createdIndex":16}]}} nil controller-manager Healthy ok nil Cluster validation succeeded Done, listing cluster services: Kubernetes master is running at http://127.0.0.1:8080
Basic Commands with example¶
Info command¶
We will add kubectl binary to path in order to manage the Kubernetes cluster.
$ export PATH=$PATH:~/kubernetes/cluster/ubuntu/binaries
$ kubectl --help
kubectl controls the Kubernetes cluster manager.
Find more information at https://github.com/GoogleCloudPlatform/kubernetes.
Usage:
kubectl [flags]
kubectl [command]
Available Commands:
get Display one or many resources
describe Show details of a specific resource
create Create a resource by filename or stdin
update Update a resource by filename or stdin.
delete Delete a resource by filename, stdin, resource and ID, or by resources and label selector.
namespace SUPERCEDED: Set and view the current Kubernetes namespace
logs Print the logs for a container in a pod.
rolling-update Perform a rolling update of the given ReplicationController.
scale Set a new size for a Replication Controller.
exec Execute a command in a container.
port-forward Forward one or more local ports to a pod.
proxy Run a proxy to the Kubernetes API server
run Run a particular image on the cluster.
stop Gracefully shut down a resource by id or filename.
expose Take a replicated application and expose it as Kubernetes Service
label Update the labels on a resource
config config modifies kubeconfig files
cluster-info Display cluster info
api-versions Print available API versions.
version Print the client and server version information.
help Help about any command
Flags:
--alsologtostderr=false: log to standard error as well as files
--api-version="": The API version to use when talking to the server
--certificate-authority="": Path to a cert. file for the certificate authority.
--client-certificate="": Path to a client key file for TLS.
--client-key="": Path to a client key file for TLS.
--cluster="": The name of the kubeconfig cluster to use
--context="": The name of the kubeconfig context to use
-h, --help=false: help for kubectl
--insecure-skip-tls-verify=false: If true, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure.
--kubeconfig="": Path to the kubeconfig file to use for CLI requests.
--log-backtrace-at=:0: when logging hits line file:N, emit a stack trace
--log-dir=: If non-empty, write log files in this directory
--log-flush-frequency=5s: Maximum number of seconds between log flushes
--logtostderr=true: log to standard error instead of files
--match-server-version=false: Require server version to match client version
--namespace="": If present, the namespace scope for this CLI request.
--password="": Password for basic authentication to the API server.
-s, --server="": The address and port of the Kubernetes API server
--stderrthreshold=2: logs at or above this threshold go to stderr
--token="": Bearer token for authentication to the API server.
--user="": The name of the kubeconfig user to use
--username="": Username for basic authentication to the API server.
--v=0: log level for V logs
--validate=false: If true, use a schema to validate the input before sending it
--vmodule=: comma-separated list of pattern=N settings for file-filtered logging
Use "kubectl help [command]" for more information about a command.
Now, we will validate if the K8s cluster created above is properly configured;
$ kubectl get nodes
NAME LABELS STATUS
127.0.0.1 kubernetes.io/hostname=127.0.0.1 Ready
The Kubernetes UI can be accessed at the following address https://127.0.0.1/ui . Suppose in case it is not accessible please run the following services and try again.
$ kubectl create -f addons/kube-ui/kube-ui-rc.yaml --namespace=kube-system
$ kubectl create -f addons/kube-ui/kube-ui-svc.yaml --namespace=kube-system
Create a Wordpress pod example¶
The below mentioned command will create a wordpress container which runs at port 80 and then expose it on the host port 81. The image ‘tutum/wordpress’ is fetched from the docker hub. By default this command will take the replication controller value as “1”.
$ kubectl run wordpress --image=tutum/wordpress --port=80 --hostport=81
CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
wordpress wordpress tutum/wordpress run=wordpress 1
After some time wordpress container will be available to be accessed at the following address http://127.0.0.1:81, which can be used to setup personal blog. We can list the pod and its replication controller as follow;
$ kubectl get pods
NAME READY REASON RESTARTS AGE
wordpress-8fz7m 1/1 Running 0 3m
$ kubectl get rc
CONTROLLER CONTAINER(S) IMAGE(S) SELECTOR REPLICAS
wordpress wordpress tutum/wordpress run=wordpress 1
Even the docker container at the node can be listed by using the following command;
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
e9e51db34a79 tutum/wordpress:latest "/run.sh" 10 minutes ago Up 10 minutes k8s_wordpress.fad11ccd_wordpress-8fz7m_default_98ab2649-2e59-11e5-8972-ecf4bb2bbd90_e34544da
9992de964017 gcr.io/google_containers/pause:0.8.0 "/pause" 10 minutes ago Up 10 minutes 0.0.0.0:81->80/tcp k8s_POD.98d1e889_wordpress-8fz7m_default_98ab2649-2e59-11e5-8972-ecf4bb2bbd90_ab95514c
In order to delete a pod, we will have to delete the replication controller.
$ kubectl delete rc wordpress
replicationcontrollers/wordpress
Deleting the Kubernetes Cluster¶
Use the following command to delete the Kubernetes Cluster
$ KUBERNETES_PROVIDER=ubuntu ./kube-down.sh
Bringing down cluster using provider: ubuntu
FLANNEL_NET
172.16.0.0/16
Cleaning on node 127.0.0.1
The authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.
ECDSA key fingerprint is ad:54:ab:4e:d0:3f:4c:32:e3:75:f7:ec:91:9e:29:6e.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '127.0.0.1' (ECDSA) to the list of known hosts.
ubuntu@127.0.0.1's password:
4405
[sudo] password for cleaning etcd data:
etcd stop/waiting
Connection to 127.0.0.1 closed.
Done