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IOTstack tutorial : local image reversion

One of the main advantages of running services in Docker containers is the relative ease of reverting to the last-known-good container.

One of the biggest problems with reverting to the last-known-good container arises if you don't already know the tag of the image you want to revert to. Sometimes it can be a bit tricky to figure it out. You usually need to go to the container's "tags" page on DockerHub, sort through the update history for your architecture, pick the appropriate tag, edit your compose file to specify that tag, and then, in the words of the old Knight in the third Indiana Jones movie, hope that you have "chosen wisely".

Your chances of choosing wisely are inversely proportional to the amount of panic you're feeling after you realise a key container isn't working and reverting is your best strategy. Panic is the enemy of clear thinking and reasoning.

There is, however, another way. The method described here means you retain the last-known-

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IOTstack tutorial: InfluxDB data merging

Scenario

A question on Discord described a situation where a new (empty) database had been created. That database contained data acquired since the rebuild but had no historical data prior to the rebuild. However, the person did have a "portable" backup of the older data and wanted to know if it was possible to merge the backup with the live data?

The answer is "yes". Merging measurements will solve this particular problem.

My test environment

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IOTstack: Understanding compose profiles

You are probably familiar with running a command like:

$ docker-compose up -d

You probably expect that command to bring up a container for every service definition mentioned in your docker-compose.yml. That's its default behaviour.

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PiBuilder + Windows: Discord question

Question 1

I tried to build a new installation using PiBuilder. I am a Windows user and connect with a terminal emulator (Putty) to the Pi. So far I was not successful. I tried to follow the description. But Windows only mounts the boot partition. The rest of the SD card is not visible to the OS. So I struggle with the step of configuring PiBuilder and also the many steps just to connect to a Pi using SSH.

Answer

macOS is the same as Windows - it can only mount the boot partition. That's why I put all the files on the boot partition. It's the easiest way of getting everything onto the Pi.

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Checking your Raspberry Pi's view of its power supply

Sometimes it seems like the first (and sometimes only) advice you get offered for almost any problem with a Raspberry Pi is "check your power supply". You think something like:

"hey, I'm using an official power supply sold as being matched with my Pi so how can there be any problem?"

You look up the specs then stick a controlled load across your supply and confirm that it can deliver the required number of Watts.

Yet your problems persist…

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IOTstack: InfluxDB 2 experiments

Update #1:

• Rewrite assuming user only has a single Raspberry Pi which is processing live data. Minimises the down time for InfluxDB 1.8.

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This gist explains the steps I followed to:

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On IOTstack, InfluxDB 1.8 & INFLUXDB_DATA_INDEX_VERSION

Updated 2022-05-19

• Additional observations since reverting to in-memory indexing.

the trigger question

On March 12 2022 I noticed a post on Discord by Ukkopahis saying:

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IOTstack and "override" files

As a general principle, I'm not in favour of override files. I think they muddy the waters. I think you're much better off editing docker-compose.yml directly.

That said…

When you use IOTstack to manage Docker containers, you have access to two override mechanisms:

1. A compose-override.yml file. This mechanism is peculiar to IOTstack and is implemented by the so-called "new" menu on the master branch.
2. A docker-compose.override.yml file. This mechanism is part of docker-compose.

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macOS Time Machine: restoring files owned by root

when you own the file …

On macOS, Time Machine pretty much just works. You delete or mutilate a file. Then you realise you want to get back to the older version so you:

1. Use the Finder to open the folder containing the file you want to restore.
2. Choose "Enter Time Machine" from the Time Machine menu.
3. Step back in the timeline until you find the version you want to restore.

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IOTstack Tutorial: Logging CPU Temperatures

introduction

This gist answers a Discord question. It explains my approach to collecting CPU temperatures by sending the data as an MQTT payload.

I like to think of this approach as working with the MING (Mosquitto, InfluxDB, Node-RED, Grafana) paradigm rather than fighting against it (eg using approaches like SSH calling out of the Node-RED container).

The approach is not tied to the Raspberry Pi that is running IOTstack. If you have several Raspberry Pis, they can all log their temperatures to the Raspberry Pi running IOTstack using exactly the same mechanism.