The recent Amazon S3 outage should make a strong argument that centralized services have severe issues, technically but from a business point of view as well(you don’t own the destiny of your own product!) and I whole heartily agree with “There is no cloud, it’s only someone else’s computer”.
Still from time to time I like to see beyond my own nose (and I prefer the German version of that proverb!) and the current exploration involves ReactJS (which I like), Tensorflow (which I don’t have enough time for) and generally looking at Docker/Mesos/Kubernetes to manage services, zero downtime rolling updates. I have browsed and read the documentation over the last year, like the concepts (services, replication controller, pods, agents, masters), planned how to use it but because it doesn’t support SCTP never looked into actually using it.
Microsoft Azure has the Azure Container Services and since end of February it is possible to create Kubernetes clusters. This can be done using the v2 of the Azure CLI or through the portal. I finally decided to learn some new tricks.
Azure asks for a clientId and password and I entered garbage and hoped the necessary accounts would be created. It turns out that the portal is not creating it and also not doing a sanity check of these credentials and second when booting the master it will not properly start. The Microsoft support was very efficient and quick to point that out. I wish the portal would make a sanity check though. So make sure to create a principal first and use it correctly. I ended up creating it on the CLI.
I re-created the cluster and executed kubectl get nodes. It started to look better but one agent was missing from the list of nodes. After logging in I noticed that kubelet was not running. Trying to start it by hand shows that docker.service is missing. Now why it is missing is probably for Microsoft engineering to figure out but the Microsoft support gave me:
sudo rm -rf /var/lib/cloud/instances
sudo cloud-init -d init
sudo cloud-init -d modules -m config
sudo cloud-init -d modules -m final
sudo systemctl restart kubelet
After these commands my system would have a docker.service, kubelet would start and it will be listed as a node. Commands like kubectl expose are well integrated and use a public IPv4 address that is different from the one used for ssh/management. So all in all it was quite easy to get a cluster up and I am sure that some of the hick-ups will be fixed…