cron.weekly issue #28: Grafana 3.0, Redis, Container Schedulers, Varnish, RHEL 6.8 and many more

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Mattias Geniar, May 15, 2016

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Welcome to _cron.weekly _issue #28 for May 15th, 2016.

It’s another fully packed edition with lots of new releases and guides to help get you started with Linux and open source.

Enjoy your sunday!


Redis Loadable Modules System

A powerful new feature coming to Redis: loadable modules. There’s already a Module Hub and plenty of modules with support for GraphicsMagick, password storage, full text search, … If you’re interested, you can create a Redis module in about 15 lines of code.

Building and scaling the Fastly network, part 1

A very revealing post about the team that builds the Fastly CDN network: instead of buying expensive network vendor hardware, they built everything themselves with open source software.

Comparison of Container Schedulers

Getting started with Docker isn’t easy, there’s so much choice: this report compares three popular solutions to schedule containers: Docker Swarm, Google Kubernetes and Apache Mesos (using the framework Marathon).

The day Google Chrome disabled HTTP/2 for nearly everyone: May 15th, 2016

The next Chrome version (51) is going to require OpenSSL 1.0.2 on the server-wide in order to support HTTP/2. Unfortunately, that’s only available in Ubuntu 16.04 LTS, only out for about a month. All other distributions don’t have support for HTTP/2 in Chrome anymore.

ZFS coming to Debian

The ZFS packages have reached the debian-contrib repository, you’ll soon be able to run the ZFS file system on your Debian systems.

A collection of Post-Mortems

Post-Mortems, or “downtime reports written by others”, can be a useful source of information. Learning what went wrong and how things got resolved can help you prevent those problems in your own infrastructure.

Tools & Projects

Kel: open-source Platform-as-a-Service

Kel is an open-source, Kubernetes-based PaaS built in Python and Go that makes it easy to manage web application deployment and hosting through the entire software lifecycle.

Rack: Open-source PaaS on AWS

And another PaaS to host yourself, this time on AWS: Rack gives you a simple developer-focused API that lets you build, deploy, scale and manage apps on private infrastructure with ease.

Cucumber testing for Varnish

A nice test-driven approach to verifying Varnish VCL configurations. This can easily be used in your CI pipeline or before any deploy of your Varnish code. (Credit where credit is due: I learned about this at the Devops Weekly newsletter)

Plasma: Readable, color-highlighted disassembler

Plasma is an interactive disassembler for x86/ARM/MIPS. Generates indented pseudo-code with colored syntax code. It basically tries to decode a binary file to its source code. Still Chinese? Click through to the screenshots in that repository.


Sandstorm is an open source operating system for personal and private clouds: you can create Google-Docs like spreadsheets, collaborate on documents, have a HipChat/Slack-like chat system and many more.

Red Hat Enterprise Linux 6.8 released

Most notable changes in this new release: it includes Libreswan (VPN), improvements to the yum package manager and lots of package upgrades. This release also marks the transition of RHEL 6 into Production Phase 2, a phase which prioritizes ongoing stability and security features for critical platform deployments.

Grafana 3.0 released

Grafana is a tool that lets you create dashboards and visualise time series data. This new release has a big UI revamp, a new CLI tool, new plugins and apps, OSX support and much more.

Certbot: Let’s Encrypt’s new CLI client

The EFF, which took care of Let’s Encrypt CLI client, introduced its new project: certbot. Certbot replaces the previous ACME client.


Flocker is an open-source Container Data Volume Manager for your Dockerized applications. Unlike a Docker data volume which is tied to a single server, a Flocker data volume, called a dataset, is portable and can be used with any container, no matter where that container is running.


A CLI tool for generating Licenses. Easily.

Guides & Tutorials

Structured text tools

A huge repository filled with tools to manipulate CSV, JSON, XML, … and all other formats from the command line.

A small DNS trick to see Sci-Hub despite censorship attempts

A nice tutorial on using the Unbound and Named DNS servers to set up your own zonefile to circumvent a DNS block by your provider.

How to install rsyslog v8 and LogAnalyzer v4 on CentOS 7

Another practical guide to improve your logging: rsyslog with a MySQL backend combined with LogAnalyzer as a visual frontend for viewing and filtering your logs.

Getting started with rkt

Rkt is a new container runtime (similar to Docker), this post gives more context and history, shows how to build images, explains the rkt terminology and Docker differences and learns you how to start/stop your containers.

Jenkins 2.0 – Pipeline as Code – Screencast Series

A practical screencast on getting started with Jenkins 2.0.

Time Series, the new shiny?

Tools like Riak, Atlas, InfluxDB, Prometheus, Splunk, … are all “time series databases”. What are they? Why did they become a thing? This post further explains the concepts of Time Series databases, from the creators of the Riak database.

Parallelising rspec-puppet

A very useful trick to speed up your rspec tests of your Puppet code: run them in parallel.

Store your private data inside a git repository

“You shouldn’t store private data in git repositories”, I can hear you think. git-secret is a tool that helps solve that, by encrypting secret data and decrypting it whenever you deploy your code.

Best Practices for those running Recursive Servers

A set of useful best practices for when you want/need to run a recursive DNS server, most probably inside your datacenter(s).

Advanced Ping: httping, dnsping, smtpping

This guide shows several layer 7 ping tools that generate HTTP, DNS, or SMTP sessions (instead of ICMP echo-requests) that can reveal whether the services (and not only the servers) are running.

An Apache trick: using directories to create redirections

A cool trick help solve the ‘trailing slash’ problems with redirects.

Linux Basics Course (Youtube)

Lots of beginner videos to help you get started with Linux: setting up a VM, basic commands, shell features, package management, …

Sysdig for ps, lsof, netstat + time travel

A good reminder on the uses of ‘ps’, ‘lsof’ and ‘netstat’ and a look at 3 new sysdig features, simulating the same tools.

Cron best practices

A set of practical tips on setting up cronjobs via crontab.

Conferences & events

Kansas Linux Fest 2016

On May 21-22 in Whichita, Kansas.

SouthEast LinuxFest

On June 10-12th, in the Sheraton Charlotte Airport  in Charlotte, NC.

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