Deploy Kubernetes on Jetstream with Kubespray 1/3

kubernetes
jetstream
Published

September 23, 2018

This tutorial is obsolete, check the updated version of the tutorial

The purpose of this tutorial series is to deploy Jupyterhub on top of Kubernetes on Jetstream. This material was presented as a tutorial at the Gateways 2018 conference, see also the slides on Figshare.

Compared to my initial tutorial, I focused on improving automation. Instead of creating Jetstream instances via the Atmosphere web interface and then SSHing into the instances and run kubeadm based commands to setup Docker and Kubernetes we will:

Create Jetstream Virtual machines with Terraform

kubespray is able to deploy production-ready Kubernetes deployments and initially targeted only commercial cloud platforms.

They recently added support for Openstack via a Terraform recipe which is available in their Github repository.

Terraform allows to execute recipes that describe a set of OpenStack resources and their relationship. In the context of this tutorial, we do not need to learn much about Terraform, we will configure and execute the recipe provided by kubespray.

Requirements

On a Ubuntu 18.04 install python3-openstackclient with APT. Any other platform works as well, also install terraform by copying the correct binary to /usr/local/bin/, see https://www.terraform.io/intro/getting-started/install.html. The current version of the recipe requires Terraform 0.11.x, not the newest 0.12.

Request API access

In order to make sure your XSEDE account can access the Jetstream API, you need to contact the Helpdesk, see the instructions on the Jetstream Wiki. You will also receive your TACC password, which could be different than your XSEDE one (username is generally the same).

Login to the TACC Horizon panel at https://tacc.jetstream-cloud.org/dashboard, this is basically the low level web interface to OpenStack, a lot more complex and powerful than Atmosphere available at https://use.jetstream-cloud.org/application. Use tacc as domain, your TACC username (generally the same as your XSEDE username) and your TACC password.

First choose the right project you would like to charge to in the top dropdown menu (see the XSEDE website if you don’t recognize the grant code).

Click on Compute / API Access and download the OpenRC V3 authentication file to your machine. Source it typing:

source XX-XXXXXXXX-openrc.sh

it should ask for your TACC password. This configures all the environment variables needed by the openstack command line tool to interface with the Openstack API.

Test with:

openstack flavor list

This should return the list of available “sizes” of the Virtual Machines.

Clone kubespray

I had to make a few modifications to kubespray to adapt it to Jetstream or backport bug fixes not merged yet, so currently better use my fork of kubespray:

git clone https://github.com/zonca/jetstream_kubespray

See an overview of my changes compared to the standard kubespray release 2.6.0.

Run Terraform

Inside jetstream_kubespray, copy from my template:

export CLUSTER=$USER
cp -LRp inventory/zonca_kubespray inventory/$CLUSTER
cd inventory/$CLUSTER

Open and modify cluster.tf, choose your image and number of nodes. Make sure to change the network name to something unique, like the expanded form of $CLUSTER_network.

You can find suitable images (they need to be JS-API-Featured, you cannot use the same instances used in Atmosphere):

openstack image list | grep "JS-API"

I already preconfigured the network UUID both for IU and TACC, but you can crosscheck looking for the public network in:

openstack network list

Initialize Terraform:

bash terraform_init.sh

Create the resources:

bash terraform_apply.sh

The last output log of Terraform should contain the IP of the master node k8s_master_fips, wait for it to boot then SSH in with:

ssh ubuntu@$IP

or centos@$IP for CentOS images.

Inspect with Openstack the resources created:

openstack server list
openstack network list

You can cleanup the virtual machines and all other Openstack resources (all data is lost) with bash terraform_destroy.sh.

Install Kubernetes with kubespray

Change folder back to the root of the jetstream_kubespray repository,

First make sure you have a recent version of ansible installed, you also need additional modules, so first run:

pip install -r requirements.txt

It is useful to create a virtualenv and install packages inside that. This will also install ansible, it is important to install ansible with pip so that the path to access the modules is correct. So remove any pre-installed ansible.

Then following the kubespray documentation, we setup ssh-agent so that ansible can SSH from the machine with public IP to the others:

eval $(ssh-agent -s)
ssh-add ~/.ssh/id_rsa

Test the connection through ansible:

ansible -i inventory/$CLUSTER/hosts -m ping all

If a server is not answering to ping, first try to reboot it:

openstack server reboot $CLUSTER-k8s-node-nf-1

Or delete it and run terraform_apply.sh to create it again.

check inventory/$CLUSTER/group_vars/all.yml, in particular bootstrap_os, I setup ubuntu, change it to centos if you used the Centos 7 base image.

Due to a bug in the recipe, run ( see details in the Troubleshooting notes below):

export OS_TENANT_ID=$OS_PROJECT_ID

Finally run the full playbook, it is going to take a good 10 minutes:

ansible-playbook --become -i inventory/$CLUSTER/hosts cluster.yml

If the playbook fails with “cannot lock the administrative directory”, it is due to the fact that the Virtual Machine is automatically updating so it has locked the APT directory. Just wait a minute and launch it again. It is always safe to run ansible multiple times.

If the playbook gives any error, try to retry the above command, sometimes there are temporary failed tasks, Ansible is designed to be executed multiple times with consistent results.

You should have now a Kubernetes cluster running, test it:

$ ssh ubuntu@$IP
$ kubectl get pods --all-namespaces
NAMESPACE       NAME                                                   READY     STATUS    RESTARTS   AGE
cert-manager    cert-manager-78fb746bc7-w9r94                          1/1       Running   0          2h
ingress-nginx   default-backend-v1.4-7795cd847d-g25d8                  1/1       Running   0          2h
ingress-nginx   ingress-nginx-controller-bdjq7                         1/1       Running   0          2h
kube-system     kube-apiserver-zonca-kubespray-k8s-master-1            1/1       Running   0          2h
kube-system     kube-controller-manager-zonca-kubespray-k8s-master-1   1/1       Running   0          2h
kube-system     kube-dns-69f4c8fc58-6vhhs                              3/3       Running   0          2h
kube-system     kube-dns-69f4c8fc58-9jn25                              3/3       Running   0          2h
kube-system     kube-flannel-7hd24                                     2/2       Running   0          2h
kube-system     kube-flannel-lhsvx                                     2/2       Running   0          2h
kube-system     kube-proxy-zonca-kubespray-k8s-master-1                1/1       Running   0          2h
kube-system     kube-proxy-zonca-kubespray-k8s-node-nf-1               1/1       Running   0          2h
kube-system     kube-scheduler-zonca-kubespray-k8s-master-1            1/1       Running   0          2h
kube-system     kubedns-autoscaler-565b49bbc6-7wttm                    1/1       Running   0          2h
kube-system     kubernetes-dashboard-6d4dfd56cb-24f98                  1/1       Running   0          2h
kube-system     nginx-proxy-zonca-kubespray-k8s-node-nf-1              1/1       Running   0          2h
kube-system     tiller-deploy-5c688d5f9b-fpfpg                         1/1       Running   0          2h

Compare that you have all those services running also in your cluster. We have also configured NGINX to proxy any service that we will later deploy on Kubernetes, test it with:

$ wget localhost
--2018-09-24 03:01:14--  http://localhost/
Resolving localhost (localhost)... 127.0.0.1
Connecting to localhost (localhost)|127.0.0.1|:80... connected.
HTTP request sent, awaiting response... 404 Not Found
2018-09-24 03:01:14 ERROR 404: Not Found.

Error 404 is a good sign, the service is up and serving requests, currently there is nothing to deliver. Finally test that the routing through the Jetstream instance is working correctly by opening your browser and test that if you access js-XX-XXX.jetstream-cloud.org you also get a default backend - 404 message. If any of the tests hangs or cannot connect, there is probably a networking issue.

Next

Next you can explore the kubernetes deployment to learn more about how you deploy resources in the second part of my tutorial or skip it and proceed directly to the third and final part of the tutorial and deploy Jupyterhub and configure it with HTTPS.

Troubleshooting notes

For future reference, disregard this.

Failing ansible task: openstack_tenant_id is missing

fixed with: export OS_TENANT_ID=$OS_PROJECT_ID, this should be fixed once https://github.com/kubernetes-incubator/kubespray/pull/2783 is merged, anyway this is not blocking.

Failing task Write cacert file:

NOTE: had to cherry-pick a commit from https://github.com/kubernetes-incubator/kubespray/pull/3280, this will be unnecessary once this is fixed upstream

(Optional) Setup kubectl locally

We also set kubectl_localhost: true and kubeconfig_localhost: true. so that kubectl is installed on your local machine

it also copies admin.conf to:

inventory/$CLUSTER/artifacts

now copy that to ~/.kube/config

this has an issue, it has the internal IP of the Jetstream master. We cannot replace it with the public floating ip because the certificate is not valid for that. Best workaround is to replace it with 127.0.0.1 inside ~/.kube/config at the server: key. Then make a SSH tunnel:

ssh ubuntu@$IP -f -L 6443:localhost:6443 sleep 3h
  • -f sends the process in the background
  • executing sleep for 3 hours makes the tunnel automatically close after 3 hours, otherwise -N would keep the tunnel permanently open

(Optional) Setup helm locally

ssh into the master node, check helm version with:

helm version

Download the same binary version from the release page on Github and copy the binary to /url/local/bin.

helm ls