Tag: Programming

A Service Monitor built with Polymer

I tried to build a service monitor having the following features:

  • showing the reachability of HTTP servers
  • plotting the amount of messages in a specific RabbitMQ queue
  • plotting the amount of queues with specific prefixes
  • showing the status of RabbitMQ queues i.e. how many messages are in there? are there any consumers? are they hung?
  • showing the availability of certain Redis clients

Well, you can find the result on GitHub.
It uses two things I published before: polymer-flot and flot-sparklines. 😀

An example dashboard:

polymer-service-monitor screen shot

too long for Unix domain socket

If you’re an Ansible user and encounter the following error:

unix_listener: "..." too long for Unix domain socket

you need to set the control_path option in your ansible.cfg file to tell SSH to use shorter path names for the control socket. You should have a look at the ssh_config(5) man page  (under

ControlPath

) for a list of possible substitutions.

I chose:

control_path = %(directory)s/ssh-%%C

Bottle Plugin Lifecycle

If you use Python‘s Bottle micro-framework there’ll be a time where you’ll want to add custom plugins. To get a better feeling on what code gets executed when, I created a minimal Bottle app with a test plugin that logs what code gets executed. I uesed it to test both global and route-specific plugins.

When Python loads the module you’ll see that the plugins’

__init__()

and

setup()

methods will be called immediately when they are installed on the app or applied to the route. This happens in the order they appear in the code. Then the app is started.

The first time a route is called Bottle executes the plugins’

apply()

methods. This happens in “reversed order” of installation (which makes sense for a nested callback chain). This means first the route-specific plugins get applied then the global ones. Their result is cached, i.e. only the inner/wrapped function is executed from here on out.

Then for every request the

apply()

method’s inner function is executed. This happens in the “original” order again.

Below you can see the code and example logs for two requests. You can also clone the Gist and do your own experiments.

https://twitter.com/riyadpr/status/617681143538786304

Android Backup and Restore with ADB

Updating my OnePlus One recently to Cyanogen OS 12 I had to reset my phone a few times before everything ran smoothly … so I wrote a pair of scripts to help me copy things around.

It uses the Android SDK’s ADB tool to do the copying since the Android File Transfer Tool for Mac has a laughable quality for Google’s standards.

Update 2018-11-22:
Since the scripts became more sophisticated I moved them to a proper project on GitHub.

JavaScript History as Seen From 2035

Gary Bernhardt presents a thought-provoking history of JavaScript as seen from 2035.

His arguments are that

  • With asm.js JavaScript VMs ran code with 50% of native speed (even in 2013)
  • Anything that can be compiled can be compiled into asm.js
  • Asm.js has basically become the universal runtime

So by further moving the JavaScript VM into the kernel we save ourselves the overhead of hardware process isolation as the VM does this any way.

All this lead to interesting consequences

  • Nobody uses binaries any more, everything is asm.js
  • The windowing systems of old have been ported to the DOM
  • Deployments are as simple as a push
  • JavaScript (as a language) is effectively dead
  • Overall developer happiness has increased

:’D