Twitter joins the rest of the world – moves to Kubernetes

Twitter Inc / The Linux Foundation

Zhang Lei, Senior Technical Experts at Alibaba reports that David McLaughlin, Product and Technical Head of Twitter Computing Platform, has announced that Twitter is switching away from Apache Mesos to Kubernetes.

You would be forgiven for thinking that Twitter was already using Kubernetes to manage all its services, given that it’s used by Netflix, Google and Facebook among many others. But Twitter has actually been using Apache Mesos, a competitor to Kubernetes.

The biggest difference between Mesos and Kubernetes is that Mesos is much more ambitious and complex. This means that it is harder to get started with Mesos rather than Kubernetes. But this isn’t likely to affect Twitter as they already have ton of experience with Mesos (they have been heavily involved in developing it) already. The biggest problem, that also affects Twitter, is the size of the open source community around both projects. Mesos is much smaller than Kubernetes meaning there are fewer developers working on it, fewer companies using it and sharing their experiences, fewer experts ready to answer questions, and so on. This is a big deal and probably the main reason why Twitter is making the switch.

Hopefully this means that Twitter will bring some of their expertise and skills to the Kubernetes community and help develop the project even further.

Quick overview of the new features in Kubernetes 1.15

Kubernetes 1.15 has been released and it comes with a lot of new stuff that will improve the way you deploy and manage services on the platform. The biggest highlights are quota for custom resources and improved monitoring.

Quota for custom resources

We have had quota for native resources for a while now but this new release allows us to create quotas for custom resources as well. This means that we can control Operators running on Kubernetes using quotas. For example you could create a quota saying each developer gets to deploy 2 Elasticsearch clusters and 10 PostgreSQL clusters.

Improved monitoring

Whether you run a production cluster, or a lab where you test stuff out, it is important to have proper monitoring so you can detect issues before they become problems. Kubernetes 1.15 comes with support for third party vendors to supply device metrics without having to modify the code of Kubernetes. This means that your cluster can use hardware specific metrics, such as GPU metrics, without needing explicit in Kubernetes for that specific device.

The metrics for storage has also improved with support for monitoring of volumes from custom storage providers.

Lastly, the monitoring performance has improved since only the core metrics are collected by kubelet.

More info

How to get it

Most users consume Kubernetes as part of a distribution such as OpenShift. They will have to wait until that distribution upgrades to Kubernetes 1.15. The latest version of OpenShift, version 4.1, comes with Kubernetes 1.13 and I would expect Kubernetes 1.15 to be available in OpenShift 4.3 which should arrive in the beginning of 2020.

Ansible 2.8 has a bunch of cool new stuff

So Ansible 2.8.0 was just released and it comes with a few really nice new features. I haven’t had time to use it much, since I just upgraded like 10 minutes ago, but reading through the Release Notes I found some really cool new things that I know I’ll enjoy in 2.8.

Automatic detection of Python path

This is a really nice feature. It used to be that Ansible always looked for /usr/bin/python on the target system. If you wanted to use anything else you needed to adjust ansible_python_interpreter. No more! Now Ansible will do a much smarter lookup where it will not only look for Python in several locations before giving up, it will adapt to the system it is executing on. So for example on Ubuntu we always had to explicitly tell Ansible to use /usr/bin/python3 since there is no /usr/bin/python by default. Now Ansible will know this out of the box.

Better SSH on macOS

Ansible moved away from the Paramiko library in favor of SSH a long time ago. Except when executed on macOS. With 2.8 those of us using a MacBook will finally get some of those sweet performance improvements that SSH has over Paramiko which will mean a lot since the biggest downside to Ansible is its slow execution.

Accessing undefined variables is fine

So when you had a large structure with nested objects and wanted to access one and give it a default if it, or any parent, was undefined you needed to do this:

{{ ((foo | default({})).bar | \
default({})).baz | default('DEFAULT') }}

or

{{ foo.bar.baz if (foo is defined and \
foo.bar is defined and foo.bar.baz is defined) \
else 'DEFAULT' }}

Ansible 2.8 will no longer throw an error if you try to access an object of an undefined variable but instead just give you undefined back. So now you can just do this:

{{ foo.bar.baz | default('DEFAULT') }}

A lot more elegant!

Tons of new modules

Of course as with any new release of Ansible there is also a long list of new modules. For example the one that I am currently most interested in are the Foreman modules. Ansible comes with just a single module for Foreman / Satellite but I have been using the foreman-ansible-modules for a while now and 2.8 deprecates the old foreman plugin in favor of this collection. Hopefully they will soon be incorporated into Ansible Core so I don’t have to fetch them from GitHub and put inside my role.

There are also a ton of fact-gathering modules for Docker such as docker_volume_info, docker_network_info, docker_container_info and docker_host_info that will be great when checking and manipulating Docker objects. Although, with RHEL 8 we will hopefully be moving away from Docker so these may come a little too late to the party, to be honest.

There’s a bunch of new KubeVirt modules which may be really cool once we move over to OpenShift 4 and run some virtual machines in it.

Other noteworthy modules are:

  • OpenSSL fact gathering for certificates, keys and CSRs
  • A whole bunch of VMware modules
  • A few Ansible Tower modules
  • A bunch of Windows modules

Red Hat OpenShift 4 is here

Wow! This is a biggie!

So Red Hat just released OpenShift 4 with a ton of new features. I haven’t had time to try it all out yet but here are some of my favorites.

RHEL CoreOS

Well, this might actually be a post on its own. This is the first new release of CoreOS after the Red Hat aquisition and serves as the successor of both CoreOS and RHEL Atomic Host. It’s basically RHEL built for OpenShift. Kinda like how RHV uses an ostree based RHEL as well.

I love Atomic Host. The OSTree model is really neat, allowing you to really lock down the operating system and do atomic upgrades. Either it works, or you roll back. There is nothing in between. And being able to lock down the OS completely (by disabling the ostree-rpm commands) means the attack surface is greatly reduced.

What CoreOS brings to the Atomic Host in this new, merged version is greater management and a more streamlined delivery of updates, as well as tighter integration with OpenShift.

Cluster management

So, that tighter integration with OpenShift is really what’s key here. This means that you can manage the lifecycle of the hosts running Kubernetes directly from Kubernetes. OpenShift 4 also comes with a new installer that uses a bootstrap node for spinning up all neccessary virtual machine for the cluster. Running OpenShift on premise will give you the exakt sweet experience as you would get running Google Kubernetes Engine or Amazon ECS. No need to manually manage virtual machine for applying updates or scaling our or in.

Service Mesh

Next up is Service Mesh. This is Red Hats supported implementation of Istio and Jaeger, two relatively new open source projects which brings some cool new features to Kubernetes for managing that growing network complexity that you get when you move more and more stuff into the microservice model.

Getting full visibility and control over the network is a great security win and you know how we at Basalt love security. I’ll sure check out OpenShift 4 and bring it into Basalt Container Platform to get that awesome new features to our customers.

Operators

Lastly is the Operators framework. This is really a natural evolvement of packaging, deploying and managing container based services. Just as CoreOS means improved management of the hosts running under OpenShift, Operators means improved management of the services running on top of it. My bet is that we will package more and more of our turn-key services such as Basalt Log Service and Basalt Monitor Service as Operators that run on top of OpenShift.

So that’s a wrap for the biggests news in OpenShift 4. I will do a deep dive later on when I get the chance and perhaps write a more detailed article when I’ve really gotten my hands dirty with it.