Author: Roo

Using Docker to isolate development environments

In terms of modern programming languages, I would pick golang as a great language to use. To me, it feels a little bit like a modernized C and has a nice approach to building single file binaries. It has a module system, type safety and garbage collection.

I really dislike the way that you install golang onto your system and the way you end up managing that install with environment variables and the like. It’s not a terrible install story, but I don’t like polluting my development laptop with cruft. Multiple versions make this more annoying.

Docker on the other hand, despite it’s flaws, is worth having installed. It allows you to run lots of different stuff without needing to make a big commitment about the install. So instead of re-imaging my machine to start fresh, I just purge the containers and start again. Another benefit is that it’s relatively easy for me to point someone else at my configuration and for them to re-use it nearly directly.

Getting a docker image that will persist state and make it trivial to compile golang programs turns out to be very easy

A couple of things to note. I’m using a host mounted volume – specifically the current directory that I issue the docker create in. From inside the container it is mapped to /data. I’ve also named the container, making it easy for me to re-run/attach to it for future compiles.

Edit – running with -u is a good idea to make docker run as the right user (you). This will mean that files created by that container on the mounted host volume are owned by you.

As an example, here is how I’d go about compiling a github project that is in golang.

How slick is that? My development machine needs docker and git installed. The rest of this environment is entirely inside the docker container.

Let me now demonstrate persistence of the container from run to run.

Thus if I happen to need a utility which isn’t installed in the base golang bullseye image, it’s easy for me to install. Also, from run to run – I have persistence of the changes I’ve made to my named image.

Ripping CDs to FLAC on Linux

This weekend I was messing around with ripping CDs again. Almost my entire collection has been digital for years, but all in MP3 format. Way back when ripping a CD to MP3 was a trade-off of time to encode, quality of playback, size of file I’d made some choices about what I was going to use as my standard for digitizing my collection.

I arrived at 192 kbps encoding (fixed bitrate), MP3 format encoded with the LAME encoder for the most part. To arrive at this bitrate I’d done a lot of A/B sampling between songs – with my best attempts at blind listening comparison to see which ones I could tell the difference between. After about 160 kbps I couldn’t hear any significant differences, and certainly after 192 kbps it was all the same. If you want to learn more about bitrates and encoding formats, this seems like a good article.

Since then – computers have gotten stupidly faster, so encoding time doesn’t matter . Storage is also cheap and plentiful, so I don’t care about file sizes. My main media server is Plex, which will happily transcode from FLAC for me to MP3 when I need it. There is also the mp3fs userspace filesystem that I can use to map FLAC to MP3 when I need it. I’d arrived at the conclusion that my archive format should be FLAC a couple of years ago, but I’d failed to get Linux setup to rip successfully.

With Windows machines there has been EAC which is basically the default way people who care will rip their music. It ensures ‘perfect’ copies. I found whipper which seemed to provide a similar solution on Linux, but a couple of years ago I failed to get this to work with either of the optical drives I have installed in my box. I could get all the tracks but the last one on the disc, very frustrating.

In my recent revisit to this, I started with abcde. This resulted in a simple docker container that I could run that would rip a disc to FLAC without much fuss. It worked well, but then I re-discovered my notes on using whipper and figured I’d see if the project had progressed.

It had – and whipper works great with one of my optical drives, but not the other. That’s fine as one is enough. My working drive is an ASUS DRW-1814BL and so far no problems except for one disc. The one problematic CD was one that I’d failed to rip in the past as well, there is a little bit of physical damage and whipper would bail dealing with the index.

It turns out my abcde setup worked great on this bad CD and was able to rip it to FLAC. I’ve less confidence that the abcde process is as robust and exact as whipper – but I’d rather have the music ripped than not at all.

For abcde I have a Makefile

And a Dockerfile

You’ll want to customize it to point at the right device, but there isn’t much here. Make build, make run and you’re good to go.

For whipper, it’s ever easier. I just used a shell script to call the pre-built container.

There is a little bit of setup for whipper, best to follow the documentation. Briefly you need to analyze the drive and figure out the offset. I also tweaked the generated config file to change the directory and file naming scheme.

That’s it. Ripping your CDs with high quality is trivial now, and with nicely featured media servers the format doesn’t matter. Now I just have to slowly re-rip CDs that I care about having high quality archives of.

 

Consumer Electronics and Leaky Batteries

Recently I’ve been working on some IR remote control stuff, this has me digging through my bin of old remotes looking for one I could use as the controller.

I had one of these classic Haupauge remotes which I’d used a long time ago with a MythTV setup. I’ve long ago retired this machine and tossed the remote into the bin. Sadly I didn’t remove the batteries, and when I opened up the battery compartment I saw that they had leaked and corroded.

This has happened to me before, and usually cleaning out the battery compartment and putting some new batteries is all that’s needed. Unfortunately not this time.

It turns out that opening this remote is easy enough, but I needed some force. The top part snaps onto the lower part – no screws. I used a metal blade to get the two parts separated a little and then was able to get a pry tool in to pop them apart. The case was surprisingly durable and it did need more force than I was comfortable using – but in this case, I figured it didn’t work so I had little to lose.

Here you can see the circuit board before I’d cleaned it up. There was quite a bit of white build-up around the chip and generally around the circuit board at the bottom. There was a recent hackaday post on restoring an old gameboy that had similar problems.

Unfortunately I was not as lucky with this remote.

The chip lost an entirely leg – and this is the power pin as well. I suppose if I was highly motivated to repair I could try grinding off the corner of the chip and then soldering a bridge inside. However, this is a bit beyond my ability to work at microscopic levels.

The lesson here is that when you stash an old remote control away – remove the batteries. For me, the remote is junk – I might strip out the IR led and re-use it somewhere, but that’s about it.