Admin

I always manage to get myself into weird issues… I have this (pretty old) wrt54g router that works well with dd-wrt v3.0-r34311 vpn release. This router is installed in an apartment intended for rental where I happen to crash every now and then. It connects to an OpenVPN hub of mine so I can monit it and be sure guests renting the apartment have working Internet access.

The apartment is located on a small mountain and electricity is not exactly stable, from times to times power goes down and comes back up. And I noticed the openvpn link sometimes fails to reconnect.

I’m running a couple of demos on how and why to use AWS Athena on a Meetup event tonight here at my hometown of Valencia. Before you start arguing about AWS services being closed source, note that Athena is “just” an hosted version of Apache Hive. Like pretty much every AWS service is a hosted version of a famous FOSS project.
One of the demos is about fetching the RSVP list and process it from a JSON source to a basic \t separated text file to be further read by Athena.
First thing is to get your Meetup API key in order to interact with Meetup’s API. Once done, you can proceed using, for example, curl:

Yeah well, it happened. In my last post I was excited to get back to a BSD UNIX (FreeBSD) for my laptop, I thought I had fought the worse when rebuilding kernel and world in order to have a working DRM module for the Intel Iris 6100 that is bundled with this MacBook Pro generation. But I was wrong. None of the BSDs around had support for the BCM43602 chip that provides WiFi to the laptop. What’s the point of a laptop without WiFi…

It is possible to run FreeBSD on a MacBook Pro from an USB drive. To achieve this, we will first prepare the USB drive from a GNU/Linux machine and make it UEFI friendly:

# apt-get install parted
# parted /dev/sdc
(parted) mklabel gpt
(parted) mkpart ESP fat32 1MiB 513MiB
(parted) set 1 boot on
(parted) quit

From there, install FreeBSD as you would for exmaple using the kvm virtual machine hypervisor on the GNU/Linux machine. Answer “yes” when the installer suggests to create a freebsd-boot partition.

At ${DAYJOB} I happen to manipulate quite a few AWS accounts for different customers, and I find it really annoying to log out from one web console, to log into a new one, with the right credentials, account ids and MFA.

Here you can read a good blog post on how to enable cross account access for third parties and use a basic script to open a web browser to switch from one account to the other.
I liked this idea so I pushed it a bit further and wrote this small piece of code which allows you not only to switch accounts, but also to simply open any AWS account from the command line.

While trying to find a clean method to remove line numbers from the history command, I found an interesting trick by using the HISTTIMEFORMAT environment variable. Here’s what bash’s man says:

       HISTTIMEFORMAT
              If  this  variable  is  set and not null, its value is used as a
              format string for strftime(3) to print the time stamp associated
              with  each  history  entry displayed by the history builtin.  If
              this variable is set, time stamps are  written  to  the  history
              file  so they may be preserved across shell sessions.  This uses
              the history comment character  to  distinguish  timestamps  from
              other history lines.

But it turns out you can actually put pretty much anything in there, and for example, an ANSI escape sequence that does a line feed and erases the current line:

Another quicky.

I read here that cool trick to convert HTML entities to plain text:

alias htmldecode="perl -MHTML::Entities -pe 'decode_entities(\$_)'"

In a Debian based system, this suppose to apt-get install libhtml-parser-perl. Why bother you may ask? Well because the (awful) Jenkins-cli outputs text areas content in encoded HTML entities, and for example I like the idea of being able to test a standalone packer template that’s failing.

Finally, here’s the full usecase:

Quick one.

While working on a build chain in order to register home-baked AMIs, I wanted to use the ansible-local packer provisioner to setup the instance with a very basic playbook. I needed to provide ansible a playbook but didn’t find immediately how to achieve this within the Jenkins-packer module. Turns out it’s tricky, in the JSON Template Text (or the template file), declare the playbook_file like this:

  [{
    "type": "ansible-local",
    "playbook_file": "{{ user `test_yml` }}",
    "command": "PYTHONUNBUFFERED=1 ansible-playbook"
  }]

Then in the File Entries field, the Variable Name must be test_yml and File Contents filled with the playbook.

Here in Spain, I chose Movistar as my Internet provider, I must say I’m pretty happy with it, symmetric 300Mbps fiber optics and good service. The only annoying aspect is that they do not provide static IP for free, something I was used to and was very convenient.

In order to reach my network from places where I can’t connect to my VPN, I wrote a very simple Dynamic DNS system using dnspython, and it turned out to be fairly easy.

pkgsrc’s collectd does not support the thermal plugin, so in order to publish thermal information I had to use the exec plugin:

LoadPlugin exec
# more plugins

<Plugin exec>
        Exec "nobody:nogroup" "/home/imil/bin/temp.sh"
</Plugin>

And write this simple script that reads CPUs temperature from NetBSD’s envstat command:

$ cat bin/temp.sh 
#!/bin/sh

hostname=$(hostname)
interval=10

while :
do
        envstat|awk '/cpu[0-9]/ {printf "%s %s\n",$1,$3}'|while read c t
        do
                echo "PUTVAL ${hostname}/temperature/temperature-zone${c#cpu} interval=${interval} N:${t%%.*}"
        done
        sleep ${interval}
done

I then send those values to an influxdb server: