Rancher automatically installs Kubernetes add-ons to help enhance the Kubernetes experience.
Helm consists of two parts, a server called tiller and a client called helm. Tiller is automatically started by Rancher and is launched in the kube-system namespace. The helm client is installed in the embedded kubectl CLI.
Before we start using helm to launch applications, let’s verify that the helm client can talk to helm server( i.e. tiller). Use helm version in the embedded kubectl CLI, which is available in Kubernetes -> CLI.
> helm version
Client: &version.Version{SemVer:"v2.1.3", GitCommit:"5cbc48fb305ca4bf68c26eb8d2a7eb363227e973", GitTreeState:"clean"}
Server: &version.Version{SemVer:"v2.1.3", GitCommit:"5cbc48fb305ca4bf68c26eb8d2a7eb363227e973", GitTreeState:"clean"}
If there is a result for both the client and server, then helm is working properly.
Similar to most package managers, we should confirm we have the latest list of charts.
> helm repo update
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "stable" chart repository
Update Complete. â Happy Helming!â
Using helm search, you can search for different charts that are available to be installed.
> helm search
NAME VERSION DESCRIPTION
stable/drupal 0.3.4 One of the most versatile open source content m...
stable/jenkins 0.1.1 A Jenkins Helm chart for Kubernetes.
stable/mariadb 0.5.2 Chart for MariaDB
stable/mysql 0.1.1 Chart for MySQL
stable/redmine 0.3.3 A flexible project management web application.
stable/wordpress 0.3.1 Web publishing platform for building blogs and ...
amit@kube1:~$
Once you’ve found the chart that you want to install, run helm install <chart_name> to install the application that you want.
> helm install stable/mysql
Fetched stable/mysql to mysql-0.1.1.tgz
NAME: loping-toad
LAST DEPLOYED: Thu Oct 20 14:54:24 2016
NAMESPACE: default
STATUS: DEPLOYED
RESOURCES:
==> v1/Secret
NAME TYPE DATA AGE
loping-toad-mysql Opaque 2 3s
==> v1/Service
NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE
loping-toad-mysql 192.16.1.5 <none> 3306/TCP 3s
==> extensions/Deployment
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
loping-toad-mysql 1 0 0 0 3s
==> v1/PersistentVolumeClaim
NAME STATUS VOLUME CAPACITY ACCESSMODES AGE
loping-toad-mysql Pending 3s
After you’ve installed the charts that you want, you can check which applications are running by using helm ls. All services are deployed in the namespace that you are currently using CLI in.
> helm ls
NAME REVISION UPDATED STATUS CHART
loping-toad 1 Thu Oct 20 14:54:24 2016 DEPLOYED mysql-0.1.1
In Rancher, each service is given a name. Other services can communicate with a service using the DNS service name. The DNS service name is <service_name>.<namespace_name>.svc.cluster.local.
Using the mysql application launched in the helm example, you can get the name and namespace of the mysql service.
> kubectl get pods --all-namespaces=true
NAMESPACE NAME READY STATUS RESTARTS AGE
default loping-toad-mysql-1951360640-gxmht 0/1 Pending 0 18m
kube-system tiller-deploy-2434200834-gvk9m 1/1 Running 0 2h
The mysql application is named loping-toad-mysql. For this instance, the DNS service name is loping-toad-mysql.default.svc.cluster.local.