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Category: Containers and Kubernetes

Toybox: Writing a new command line from scratch

Rob Landley, of Busybox/Toybox fame, spoke four years ago about the Toybox project in the context of Android and whatever else was recent back then. The talk contains a brilliant deconstruction of the problems that GPL v3 has, and why it is in decline.

It also shows a lot of vision re containers, and what is needed in this context. If you are deploying Alpine today, with musl and toybox in it, here is why and how it came to be.

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jq

When dealing with Kubernetes, you will inevitably have to deal with config and data that is in JSON format.

jq is a cool tool to handle this, but while the man page is complete, it is also very dry. A nice tutorial can be found at The Programming Historian, which uses some real world use cases. My personal use case is Converting JSON to CSV, and the inverse of that. There also is a mildly interesting FAQ.

Learning jq takes about one quiet afternoon of time.

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Understanding sysdig

The open source sysdig is a piece of software that does not quite, but almost, what strace or oprofile do: It instrument the kernel, and traces system calls as well as a few other kernel activities.

It does not utilize the ptrace(2) kernel facility, though, but its own interface. This interface picks up data in the kernel and writes it into a ring buffer.

A userspace component extracts this data, interprets, filters and formats it, and then shows it. If the data source outpaces the userspace, the ring buffer overflows and events are lost, but the actual production workload is never slowed down.

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Curlbash, and Desktop Containers

I was having two independent discussions recently, which started with some traditional Unix person condemning software installing with curlbash (“curl https://… | bash”), or even “curl | sudo bash”.

I do not really think this to be much more dangerous than the installation of random rpm or dpkg packages any more. Especially if those packages are unsigned or the signing key gets installed just before the package.

The threat model really became a different one in the last few years, and the security mechanism have had to change as well. And they have, UIDs becoming much less important.

Desktop containers and Sandboxes have become much more important, and segregation happens now at a much finer granularity (the app level) instead of the user level.

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The Illustrated Guide to Kubernetes

»The other day, my daughter sidled into my office, and asked me, “Dearest Father, whose knowledge is incomparable, what is Kubernetes?”

And I responded, “Kubernetes is an open source orchestration system for Docker containers. It handles scheduling onto nodes in a compute cluster and actively manages workloads to ensure that their state matches the users’ declared intentions. Using the concepts of “labels” and “pods”, it groups the container which make up an application into logical units for easy management and discovery.”

And my daughter said to me, “Huh?”

And so I give you…«

Video: https://www.youtube.com/watch?v=4ht22ReBjno

Comic: The Illustrated Guide to Kubernetes

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Back from Kubecon

Right on the heels of the Openshift Commons and co-located with them, Kubecon 2017 happened at the BCC in Berlin. Supposedly 1500 people attended, which was straining BCC’s capacity to the limit, especially on the A-level. Room A03, which hosted the “Deep Dive track” was continuously overcrowded and could not accommodate all interested people.

Also, this was the most noisy event I have been attending in a long time, especially in the vendor booth setup in B01/B02. On the other hand, the hallway track was exceptionally useful, especially if one escaped out the door, weather permitting, or upstairs.

Quite a bit of content was a duplicate from the Openshift Commons Gathering preceding the Kubecon, but the inclusion of rkt and containerd as CNCF projects have been news and are very welcome.

Especially rkt will be useful, as Docker is not doing very many useful things in the context of Kubernetes and rkt kind of restricts itself to doing only these useful things and not having any other, less useful (in the K8s context) code.

At the CoreOS booth I learned that rkt is right now not yet a drop-in replacement for Docker, but may well be soon – work is being done, and quickly.

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Back from Openshift Commons

So I have been to Berlin this week, for the Openshift Commons Gathering and Kubecon, and of course to meet a few Berliners.

Openshift is Redhats distribution of Google Kubernetes, plus their own enhancements. It is available on your own machines as Openshift Origin (the GPL version) or OCP (Open Container Project). Redhat also operates dedicated and public clouds based on this. The Openshift Commons Gathering is a meeting of the Openshift Users Community, Commons.

Commons was a nice and fine gathering in the basement level of the BCC, a single track event with a nice mix of users reporting back  their experience with Kubernetes and Openshift. In fact, Commons already had quite a bit of the content later duplicated in Kubecon, but in a smaller and less noisy setting.

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Netways OSDC 2017: Something Openshift Kubernetes Containers

OSDC 2017 Registration
I will be speaking at the Netways Open Source Data Center Conference, which is in Berlin between May 16 and 18.

At work, we are currently busy loading our first two Kubernetes Clusters (Openshift actually) with workloads.

What exactly will be in the slides I do not know, yet, but it will be about our journey at Booking, the transition from automated baremetal provisioning of rather monolithic applications to a more containerized setup and the changes and challenges this brings. It will be very much a snapshot of the state of things at that point in time, and our learnings and perspective then.

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