Entries posted in September 2017

After 13 years the Debian-Administration website will be closing down towards the end of the year.

The site will go read-only at the end of the month, and will slowly be stripped back from that point towards the end of the year - leaving only a static copy of the articles, and content.

This is largely happening due to lack of content. There were only two articles posted last year, and every time I consider writing more content I lose my enthusiasm.

There was a time when people contributed articles, but these days they tend to post such things on their own blogs, on medium, on Reddit, etc. So it seems like a good time to retire things.

An official notice has been posted on the site-proper.

Tags: debian-administration | 8 comments

So previously I've documented the setup of the Debian-Administration website, and now I'm going to retire it I'm planning how that will work.

There are currently 12 servers powering the site:

• web1
• web2
• web3
• web4
  • These perform the obvious role, serving content over HTTPS.
• public
  • This is a HAProxy host which routes traffic to one of the four back-ends.
• database
  • This stores the site-content.
• events
  • There was a simple UDP-based protocol which sent notices here, from various parts of the code.
  • e.g. "Failed login for bob from 1.2.3.4".
• mailer
  • Sends out emails. ("You have a new reply", "You forgot your password..", etc)
• redis
  • This stored session-data, and short-term cached content.
• backup
  • This contains backups of each host, via Obnam.
• beta
  • A test-install of the codebase
• planet
  • The blog-aggregation site

I've made a bunch of commits recently to drop the event-sending, since no more dynamic actions will be possible. So events can be retired immediately. redis will go when I turn off logins, as there will be no need for sessions/cookies. beta is only used for development, so I'll kill that too. Once logins are gone, and anonymous content is disabled there will be no need to send out emails, so mailer can be shutdown.

That leaves a bunch of hosts left:

• database
  • I'll export the database and kill this host.
  • I will install mariadb on each web-node, and each host will be configured to talk to localhost only
  • I don't need to worry about four database receiving diverging content as updates will be disabled.
• backup
  • This will be retired, as nowadays Bytemark provide cloud-backups.
• planet
  • This will become orphaned, so I think I'll just move the content to the web-nodes.

All in all I think we'll just have five hosts left:

• public to do the routing
• web1-web4 to do the serving.

I think that's sane for the moment. I'm still pondering whether to export the code to static HTML, there's a lot of appeal as the load would drop a log, but equally I have a hell of a lot of mod_rewrite redirections in place, and reworking all of them would be a pain. Suspect this is something that will be done in the future, maybe next year.

Tags: debian-administration | 2 comments

So recently I was in York at the Bytemark office, and I read a piece about building a radio in a Raspberry Pi magazine. It got me curious, so when I got home to sunny Helsinki I figured I'd have a stab at it.

I don't have fixed goal in mind, but what I do have is:

• A WeMos Mini D1
  • Cost €3.00
  • ESP8266-powered board, which can be programmed easily in C++ and contains on-board WiFi as well as a bunch of I/O pins.
• A RDA5807M FM Radio chip.
  • Cost 37 cents.
  • With a crystal for support.

The initial goal is simple wire the receiver/decoder to the board, and listen to the radio.

After that there are obvious extenstions, such as adding an LCD display to show the frequency (What's the frequency Kenneth), and later to show the station details, via RDS.

Finally I could add some buttons/switches/tweaks for selecting next/previous stations, and adjusting the volume. Initially that'll be handled by pointing a browser at the IP-address of the device.

The first attempt at using the RDA5807M chip was a failure, as the thing was too damn small and non-standardly sized. Adding header-pins to the chips was almost impossible, and when I did get them soldered on the thing just gave me static-hisses.

However I later read the details of the chip more carefully and realized that it isn't powerfull enough to drive (even) headphones. It requires an amp of some kind. With that extra knowledge I was able to send the output to the powered-speakers I have sat beside my PC.

My code is basic, it sets up the FM-receiver/decoder, and scans the spectrum. When it finds a station it outputs the name over the serial console, via RDS, and then just plays it.

I've got an PAM8403-based amplifier board on-order, when that arrives I'll get back to the project, and hookup WiFi and a simple web-page to store stations, tuning, etc.

My "token goal" at the moment is a radio that switches on at 7AM and switches off at 8AM. In addition to that it'll serve a web-page allowing interactive control, regardless of any buttons that are wired in.

I also have another project in the wings. I've ordered a software-defined radio (USB-toy) which I'm planning to use to plot aircraft in real-time, as they arrive/depart/fly over Helsinki. No doubt I'll write that up too.

Tags: esp8266, radio, youtube | 2 comments