cron.weekly issue #83: Humble Bundle, Sudo, kapo, slap, Node, MySQL, iostat & more

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Mattias Geniar, June 04, 2017

Follow me on Twitter as @mattiasgeniar

Welcome to cron.weekly issue #83 for Sunday, June 4th, 2017.

It took a bit longer to get this issue out, but as usual – there were a lot of links & content to get through.

Now’s probably a good time to highlight the sponsor options for the newsletter, as I’ve got several available slots in the upcoming weeks. If you like to promote something or help support the newsletter, go have a look.

Enjoy your Sunday & the newsletter!


Linux Namespaces And Go Don’t Mix

A tale of debugging a Go program that makes use of namespacing. Conclusion seems to be you can’t (yet?) safely change namespaces in Go.

Open Source Survey

This survey was started by Github and independent researchers, reaching some interesting conclusions. Good documentation breaks or makes an open source project, negative interactions are infrequent by (unfortunately) highly visible, influencing the project activity.

Why We Open Sourced our Books

All the books by underscore are now offered for free, this post dives into the rationale of open sourcing them. If you’re into Scala, they do look interesting.

Linux Humble Bundle

It’s e-book time! For 15$ you get books on high scalability clustering, Docker, Nginx, Vim, OpenStack, … even if you don’t think you need them just yet, they look like they’re well worth it anyway.

MySQL 8.0: Retiring Support for the Query Cache

In an unsurprising move (at least to me), MySQL 8 will remove the concept of a “query cache”. This post describes the reasoning and the shortcomings of the query cache.

Unmanaged, orphaned SSH keys remain a serious enterprise risk

In big corporations, SSH keys get added to servers and they stay there, without anyone knowing it. Obviously, this poses a security risk.

CVE-2017-1000367: limited use of sudo could grant root access

There’s a vulnerability in (nearly) every sudo implementation, where a user that was granted sudo access to some binaries, could get root on your server. Time to update sudo!

Tools & Projects

Datadog: all your infrastructure, in one place

Track & alert on the health and performance of every server, container, and app in any environment, with Datadog. Sign up for a free 14-day trial. (Sponsored)

DNS Spy: Monitor, alert & validate your DNS configurations

You know what sucks? Having an unexpected DNS change. Or waiting for a DNS change that doesn’t come through. Stop waiting & start monitoring! DNS Spy alerts you of any DNS change, wanted or unwanted, to any of your domains. And you know what’s great? It’s free for Open Source project maintainers. (Sponsored)


Minishift is a tool that helps you run OpenShift locally by running a single-node OpenShift cluster inside a VM. You can try out OpenShift or develop with it, day-to-day, on your local host.


Kapo is a swiss-army knife for integrating programs that do not have their own method of presenting their status over a network with those that need it.


slap is a Sublime-like terminal-based text editor that strives to make editing from the terminal easier.

Node v8

A new major release of the Node project, 8.0.

npm 5.0

With a new major Node version, there’s also a new major npm version. This version takes a lot of (good) ideas from Yarn to the table.


Connbeat, short for ‘Connectionbeat’, is an open source agent that monitors TCP connection metadata and ships the data to Kafka or Elasticsearch, or an HTTP endpoint.

Guides & Tutorials

RHEL7: How to get started with CPU governor

A step-by-step guide on power saving by influencing the CPU functionalities and a glimps of powertop to see which component is consuming most power.

Differences between tmux vs screen

This post gives a good comparison of these two “virtual terminals”.

MySQL data dump avoid global lock in parallel mode

This post introduces “datapumper“, a tool to dump percona mysql innodb tables faster.

Linux Scheduling Commands With at, atq, atrm and batch Examples

This post compares and demonstrates several scheduling commands on Linux.

Secure your SSH using two-step authentication on CentOS 7

Combine Google’s Authenticator (for Android/iOS) with your SSH daemon on your server.

The first 5 things to do when your Linux server keels over

Several steps to take when your server rolls over and dies, including hardware troubleshooting, checking the running state of applications, troubleshooting with top, ….

Tor Socks Proxy and Privoxy Containers

Last _cron.weekl__y _showed how to setup a SOCKS proxy via SSH, this post does the same via Docker, and it’s a lot easier.

Linux iostat Command Tutorial With Examples

Linux iostat is part of the sysstat utilities. iostat command is mainly used to track input output related events and issues. iostat command can provide metrics, information and statistics about input and output.

Scaling with ProxySQL Query Cache

The ProxySQL Query Cache has a completely different nature than MySQL Query Cache. It is an in-memory key/value storage. This post gives you insights into how it works and how to use it.

What About ProxySQL and Mirroring?

A bit of a counter argument to using ProxySQL, as shown above. Even more insights into ProxySQL, from a slightly more critical angle.

Writing a Unix Shell – Part I

If you like C code examples, you’ll like this: a step-by-step guide on how to write your own Unix shell. If you understand C code, this gives you plenty of insights into how a shell works.

An introduction to programming in Go

A free online book with everything you need to get started with the Go programming language.

Raspberry Pi VPN Server: Build Your Own Virtual Private Network

We’ve all got a Pi at home, don’t we? This post covers building your own VPN server on it.

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