Running Consul for service discovery in Docker containers

I’ve been looking at Spring Boot services in Docker and options for Service Discovery. I started looking at Eureka a while back, but just took a look at Consul.

Here’s my docker-compose.yml that I’ve got working so far. I realize this is just Consul running in 3 containers (1 server, and 2 containers with Consul agents), but I was interested in taking a look at how the containers register with the main server and how it’s configured.

One of the agent containers is running the UI on port 8500, this looks interesting to get an overview of what’s registered with the Consul server.

More to come later.

River City Amateur Radio Communications Society weekly SSTV net (06/21/17)

The River City Amateur Radio Communications Society in Sacramento runs a weekly SSTV net Wednesdays at 9pm local time (following the 2m net on the 2m N6NA repeater, and the 10m net) – I’ve tried to receive the pictures before but on 2m simplex between most of the stations in Sacramento area and out to my QTH in Davis, it’s a bit far to get a good copy, and some of the stations I can’t copy at all.

This week we tried something different and ran the net on the club’s 440MHz repeater. This worked great for me as we’ve got great coverage from this repeater over Sacramento area and surrounding area.

This was my first time to actively check-in on the net so I had a few things to learn on the fly! First, Multiscan 3B, what seems like one of the most common SSTV apps for the Mac, doesn’t seem to run reliably on current OS X 10.12.x versions. Last time I tried to use it I didn’t have any issue, but with the most recent MacOS version it would only start up the first time after it was installed, and every other time it crashed.


The first couple of pictures I received I realized I was receiving through the built in mic, and wasn’t even receiving via my Rigblaster interface. Understandably these first few pics were pretty terrible:

Part way through the net I switched to installing MMSSTV on Windows 10 running under Parallels on my Mac. My connection to my radio is through a Rigblaster, so I had to attach the Rigblaster input and output USB device to my Windows 10 guest. Once I configured it to receive and send through my Rigblaster interface, now I was receiving great images from the other ops on the net, and managed to send and get good reports on a couple of pictures myself:








Now I’ve got my config setup, I’m looking forward to our next SSTV net!

Never assume you know how something works by only observing its external behavior

As a developer, you should never assume you understand how something works solely by observing what it does. This is especially true if you are trying to fix something and your only understanding of the issue is only the behavior that you can observe.

While you don’t have to understand how something works in order to use it, if you’re trying to fix something, especially software, it helps to understand how something works. The reason is what you observe externally as a problem is usually only a symptom of the problem; it’s rarely the actual problem itself.

Let me give you an extremely simplified example. Let’s say you have an electric car, but you’ve no idea how the electric motor drivetrain works, you just know you press the accelerator pedal and it goes. One morning you get in the car and press the pedal and nothing happens. In diagnosing the issue, the only thing you consider is the external symptoms that you can see: you press the pedal and it doesn’t go. An extremely naive conclusion you could make is that the accelerator pedal is broken (!). So you replace the pedal, but then you’re surprised to find that it still doesn’t work (ok, so this is a contrived example to make the point – if you know enough to be able to replace the accelerator pedal, you probably know enough about how the car works to not assume the pedal is broken!)

As a software developer or architect, as you diagnose issues you should always look under the covers and find out more about what’s actually going on. The problem you’re looking for is rarely the symptom that you can actually see (or what the user sees).

Installing El Capitan on my 2008 Mac Pro

My 2008 Mac Pro arrived, and it’s a shiny beast of a machine πŸ™‚ Β It’s sitting beside a younger relative, a 2002 Power Mac G4 Quicksilver.

It came with OS X 10.5 Leopard installed – it looked like it was a clean install, but as for any used machine, I like to do a clean install so I know what I’m starting with. Downloading OS 10.11 El Capitan from the Apple Store from my MacBook Pro, I created a bootable USB flash drive using the steps described here.

On my first attempt to install, it looked like after about 20 mins of install when it attempted to reboot for the first time, I had a blank screen and no activity. Rebooted back to the USB flash drive and started the Disk Utils, the drive checked clean and everything was good, but there wasn’t a bootable partition.

On the second attempt, I think what had happened the first time was the powersave settings had kicked in and the monitor output had turned off, but it wasn’t waking from keyboard or mouse input. The second time the screen turned back on, and the installer was stuck at ‘about a second remaining’,

but pressing Cmd-L to see the installer logs, there was a huge amount of errors scrolling by to do with TSplicedFont and Noto fonts. This seems to be a common issue with El Capitan, as described here. Ignoring the errors and waiting it out though, after about 20 mins stuck at ‘about a second remaining’ it did reboot and the installation continued as expected.

After successfully completing the install, it started up successfully, and after walking through the installation dialogs to select language preferences and create an account, I was up and running with 10.11 El Cap.

First impressions: for a 9 year old computer, this thing is pretty snappy. It’s comparable to my 2012 MacBook Pro with an i7 in responsiveness, although from only having a regular mechanical HDD, it could be faster booting and loading apps, but it’s definitely acceptable. For a desktop daily driver, it’s definitely perfectly usable. The dual Xeon 2.8GHz CPUs are holding their own, I haven’t seen anything beyond 5% to 6% CPU usage from using Chrome and browsing the web with about 20 or so tabs open. Where I think I might start to suffer though is this machine only came with 4GB RAM. With my current Chrome usage it’s eating up about 3GB so I have some to spare, but the interesting thing about these Mac Pros is the expandability – the 2008 will support 32GB per specs and 64GB unofficially. I bet if I put in 16GB or so I would get a much better experience. Time to plan the upgrades πŸ™‚