Helm
Exercise 15.1: Working with Helm and Charts
Overview
helm allows for easy deployment of complex configurations. This could be handy for a vendor to deploy a multi-part application in a single step. Through the use of a Chart, or template file, the required components and their relationships are declared. Local agents like Tiller use the API to create objects on your behalf. Effectively its orchestration for orchestration.
There are a few ways to install Helm. The newest version may require building from source code. We will download a recent, stable version. Once installed we will deploy a Chart, which will configure Hadoop on our cluster.
Install Helm
- On the master node use wget to download the compressed tar file. The short URL below is for: https://storage.
googleapis.com/kubernetes-helm/helm-v2.7.0-linux-amd64.tar.gz
student@lfs458-node-1a0a:~$ wget goo.gl/nbEcHn <output_omitted> nbEcHn 100%[====================>] 11.61M --.-KB/s in 0.1s 2018-08-03 05:34:56 (91.7 MB/s) - nbEcHn saved [12169373/12169373] - Uncompress and expand the file.
student@lfs458-node-1a0a:~$ tar -xvf nbEcHn linux-amd64/ linux-amd64/README.md linux-amd64/helm linux-amd64/LICENSE - Copy the helm binary to the /usr/local/bin/ directory, so it is usable via the shell search path.
student@lfs458-node-1a0a:~$ sudo cp linux-amd64/helm /usr/local/bin/ - Due to new RBAC configuration helm is unable to run in the default namespace, in this version of Kubernetes. During initialization you could choose to create and declare a new namespace. Other RBAC issues may be encountered even then. In this lab we will create a service account for tiller, and give it admin abilities on the cluster. More on RBAC in
another chapter.
Begin by creating the serviceaccount object.student@lfs458-node-1a0a:~$ kubectl create serviceaccount \ --namespace kube-system tiller serviceaccount "tiller" created - Bind the serviceaccount to the admin role called cluster-admin inside the kube-system namespace.
student@lfs458-node-1a0a:~$ kubectl create clusterrolebinding \ tiller-cluster-rule \ --clusterrole=cluster-admin \ --serviceaccount=kube-system:tiller clusterrolebinding.rbac.authorization.k8s.io/tiller-cluster-rule created -
We can now initialize helm. This process will also configure tiller the client process. There are several possible options
to pass such as nodeAffinity, a particular version of software, alternate storage backend, and even a dry-run option
to generate JSON or YAML output. The output could be edited and ingested into kubectl. We will use default values in
this case.
student@lfs458-node-1a0a:~$ helm init <output_omitted> - Update the tiller-deploy deployment to have the service account.
student@lfs458-node-1a0a:~$ kubectl -n kube-system patch deployment \ tiller-deploy -p \ ’{"spec":{"template":{"spec":{"serviceAccount":"tiller"}}}}’ deployment.extensions/tiller-deploy patched - Verify the tiller pod is running. Examine the logs of the pod. Note that each line of log begins with an tag of the
component generating the messages, such as [main], [storage], and [storage].
student@lfs458-node-1a0a:~$ kubectl get pods --all-namespaces <output_omitted> kube-system tiller-deploy-84b97f465c-76lvs 1/1 Running 0 30m student@lfs458-node-1a0a:~$ kubectl -n kube-system logs \ tiller-deploy-84b97f465c-76lvs <output_omitted> -
View the available sub-commands for helm. As with other Kubernetes tools, expect ongoing change.
student@lfs458-node-1a0a:~$ helm help <output_omitted> -
View the current configuration files, archives and plugins for helm. Return to this directory after you have worked with a
Chart later in the lab.
student@lfs458-node-1a0a:~$ helm home /home/student/.helm student@lfs458-node-1a0a:~$ ls -R /home/student/.helm/ /home/student/.helm/: cache plugins repository starters /home/student/.helm/cache: archive <output_omitted> - Verify helm and tiller are responding, also check the current version installed.
student@lfs458-node-1a0a:~$ helm version Client: &version.Version{SemVer:"v2.7.0", GitCommit:"08c1144f5... Server: &version.Version{SemVer:"v2.7.0", GitCommit:"08c1144f5... -
Ensure both are upgraded to the most recent stable version.
student@lfs458-node-1a0a:~$ helm init --upgrade $HELM_HOME has been configured at /home/student/.helm. Tiller (the Helm server-side component) has been upgraded to the current version. Happy Helming! -
A Chart is a collection of containers to deploy an application. There is a collection available on https://github.com/kubernetes/charts/tree/master/stable, provided by vendors, or you can make your own. Take a moment and view the current stable Charts. Then search for available stable databases.
student@lfs458-node-1a0a:~$ helm search database NAME VERSION DESCRIPTION stable/cockroachdb 2.0.3 CockroachDB is a scalable, survivable,... stable/dokuwiki 3.3.0 DokuWiki is a standards-compliant, ... stable/janusgraph 0.2.0 Open source, scalable graph database. stable/kubedb 0.1.3 DEPRECATED KubeDB by AppsCode - Making... stable/mariadb 5.2.3 Fast, reliable, scalable, and easy to use... <output_omitted> - We will install the mariadb. Take a look at install details https://github.com/kubernetes/charts/tree/master/stable/mariadb#custom-mycnf-configuration The –debug option will create a lot of output. Note the interesting name for the deployment, like illmannered-salamander. The output will typically suggest ways to access the software. As well we will indicate that we do not want persistent storage, which would require use to create an available PV.
student@lfs458-node-1a0a:~$ helm --debug install stable/mariadb \ --set master.persistence.enabled=false \ --set slave.persistence.enabled=false [debug] Created tunnel using local port: ’38396’ [debug] SERVER: "localhost:38396" [debug] Original chart version: "" [debug] Fetched stable/mariadb to /home/student/.helm/cache/archive/mar... [debug] CHART PATH: /home/student/.helm/cache/archive/mariadb-2.0.1.tgz NAME: illmannered-salamander <output_omitted> - Using some of the information at the end of the previous command output we will deploy another container and access the database. We begin by getting the root password for
illmannered-salamander. Be aware the output lacks a carriage return, so the next prompt will appear on the same line. We will need the password to access the running MariaDB database.student@lfs458-node-1a0a:~$ kubectl get secret -n default \ illmannered-salamander-mariadb \ -o jsonpath="{.data.mariadb-root-password}" \ | base64 --decode IFBldzAQfx - Now we will install another container to act as a client for the database. We will use apt-get to install client software.
student@lfs458-node-1a0a:~$ kubectl run -i --tty ubuntu \ --image=ubuntu:16.04 --restart=Never -- bash -il If you don’t see a command prompt, try pressing enter. root@ubuntu:/# root@ubuntu:/# apt-get update ; apt-get install -y mariadb-client <output_omitted> - Use the client software to access the database. The following command uses the server name and the root password
we found in a previous step. Both of yours will be different.
root@ubuntu:/# mysql -h illmannered-salamander-mariadb -p Enter password: IFBldzAQfx Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 153 Server version: 10.1.28-MariaDB Source distribution Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others. Type ’help;’ or ’\h’ for help. Type ’\c’ to clear the current input statement. MariaDB [(none)]> SHOW DATABASES; +--------------------+ | Database | +--------------------+ | information_schema | | my_database | | mysql | | performance_schema | | test | +--------------------+ 5 rows in set (0.00 sec) MariaDB [(none)]> MariaDB [(none)]> quit root@ubuntu:/# exit - View the Chart history on the system. The use of the -a option will show all Charts including deleted and failed
attempts. The output below shows the current running Chart as well as a previously deleted hadoop Chart.
student@lfs458-node-1a0a:~$ helm list -a NAME REVISION UPDATED STATUS CHART NAMESPACE goodly-beetle 1 Wed Nov 8 23:01:24 2017 DELETED hadoop-1.0.1 default illmannered-salamander 1 Thu Nov 9 05:00:12 2017 DEPLOYED mariadb-... - Delete the mariadb Chart. No output should happen from the list.
student@lfs458-node-1a0a:~$ helm delete illmannered-salamander release "illmannered-salamander" deleted student@lfs458-node-1a0a:~$ helm list - Add another repository and view the Charts available.
student@lfs458-node-1a0a:~$ helm repo add common \ http://storage.googleapis.com/kubernetes-charts "common" has been added to your repositories student@lfs458-node-1a0a:~$ helm repo list NAME URL stable https://kubernetes-charts.storage.googleapis.com local http://127.0.0.1:8879/charts common http://storage.googleapis.com/kubernetes-charts student@lfs458-node-1a0a:~$ helm search NAME VERSION DESCRIPTION stable/acs-engine-autoscaler 2.1.0 Scales worker nodes within... stable/artifactory 6.2.0 Universal Repository Manag... <output_omitted>
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