What?
Openstack Magnum is the Container Infrastructure service, which gives you the possibility to create kubernetes clusters as native resources in Openstack. For more information about the service, and offical documentaions, read the user guide and the Magnum Wiki page
How
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to use Openstack Magnum
To use Magnum you need to have the openstack magnum clients installed. You have two alternatives:
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- If you want to use the openstack CLI on your local system, install python3-openstackclient and python3-magnumclient from the repositories suiting your Operating System. Make sure you install the version corresponding to the Openstack version we are running in production (listed on this Wikis frontpage).
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- The clients are pre-installed on NTNUs logon servers
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- . We've made sure we have the correct version
When the client is ready to be used, you can start creating kubernetes clusters.
Cluster Templates
To get you started, there is a few public Cluster Templates available in our cloud, which installs a specific version of kubernetes. These templates are verified working by us.
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For more information, all templates can be listed and inspected with the following commands:
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$ openstack coe cluster template list # And then $ openstack coe cluster template show <id|name> # To view details |
Private templates can be created by usersIf the provided templates does not suit your needs, you can create your own private templates. Please consult the documentation to find which parameters is needed for different Container Orchestration Engines. We do however recommend to start a cluster from the public templates first so that you know how it looks.
Create a cluster
For an extensive and complete list of parameters, check the documentation.
Examples
. The guide here shows you the minimum needed to create a cluster.
When creating a cluster from a For each template, you can override a few parameters when you create your cluster:
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Do NOT select flavors with less resources than the default in our templates. The k8s masters will need a certain amount of RAM to function. |
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| Parameter | Comment |
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| --docker-volume-size | Size of cinder volume housing docker images and volumes. Defaults to 20GB for our public templates |
| --master-flavor | Instance flavor of VMs running the master node. Defaults to gxN.2c4r for public templates |
| --flavor | Instance flavor of VMs runnin worker nodes. Defaults to gxN.2c4r for public templates |
| --labels | Override default labels for the give COE. Consult documentation for valid labels for each COE. Note the labels set in the public templates are there for a reason Also note that --labels does not merge by default, so if you want to add labels, please add --merge-labels as well |
Kubernetes
This will create Creating a small kubernetes cluster with one master node, and one worker-cluster can typically be done using a command like so:
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$ openstack coe cluster create <clustername> --cluster-template kubernetes-v1.xx.xx --master-count 1 --node-count 1 --keypair <your keypair> |
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Using the kubernetes cluster
Kubernetes
You can interact with your kubernetes cluster with kubectl. When using kubectl you have at least two options:
- Install it
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- on your local PC, if you don't already have it. Use the Install-guide
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- .
- Use the NTNU login-servers (login.stud.ntnu.no for students or login.ansatt.ntnu.no for employees), as they already have kubectl installed.
Preparing your kubectl configuration
Openstack magnum can help create configuration-files to kubectl for you. In practice you create a directory where the openstack-client can write the kubectl config like soSource your cluster config:
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$ mkdir -p ~/clusters/kubernetes-cluster $ $(openstack coe cluster config <your-cluster> --dir ~/clusters/kubernetes-cluster export KUBECONFIG=/home/demo/clusters/kubernetes-cluster) |
That should just work, and you can run kubectl commands as you please.
Example, to check if services are running
/config |
The openstack command prints out a helpful hint on how to tell kubectl which config-file to use. This will help you select the correct cluster if you have config-files for multiple clusters.
Using the kubectl configuration from the openstack command
You need to point the environment-variable "KUBECONFIG" to the kubernetes configuration-file you need to use. To do this you basically run the output from the "openstack coe cluster config" command as a command:
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$ export KUBECONFIG=/home/demo/clusters/kubernetes-cluster/config
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$ kubectl get nodes NAME STATUS ROLES AGE VERSION mycluster-o56ashbsrqqa-master-0 Ready master 131m v1.15.12 mycluster-o56ashbsrqqa-minion-0 Ready <none> 131m v1.15.12 mycluster-o56ashbsrqqa-minion-1 Ready <none> 131m v1.15.12 |
At this point your cluster is running, and you can use it as a regular kubernetes cluster.
Using your openstack credentials to auth with kubectl
Our public kubernetes template does not have the keystone auth module enabled by default. But if you choose to enable it via label overrides, that makes it possible to interact with your newly created cluster via the environment variables from your opencrc file. If you want that, configure kubectl to use openstack auth as follows:
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