Fixing the caching_sha2 problem with wordpress and mysql verion 8

The problem

I am using wordpress with mysql both in a docker installation. The procedure for my setup is described here. Since mysql updated to version 8 they introduced caching_sha2 as the default password algorithm. When you use the auto update mechanism in wordpress everything is fine and wordpress still works with the native password version configured for the wordpress user. But if you use wordpress in a docker container and pull wordpress:latest there is a problem since wordpress 4.9.7 to access the mysql database: (Never thought I can use the word wordpress so many times in a sentence!)

The solution

The solution is relatively easy. You need to change the wordpress user manually from ​”mysql_native_password” to “caching_sha2_password“. This can be done with a simple SQL call. First stop your wordpress docker container and keep the mysql docker container running. Then execute these commands.

Replace blog_wordpress_db_1 with your mysql docker instance name (“docker ps”), “REALLYEPICSECURE” with your root password and “wordpressuser” with your wordpress username.

That is basically all. Now you can start your wordpress:latest docker container again and it should work.


Adding a ks0212 relay board to the mqtt universe

Weatherstation with raspi
Weatherstation with raspi

Adding the 4 channel relay board ks0212 to the MQTT universe

We just hacked a trotec dehumidifier for Herwigs Observatory. The idea was to additionally activate the dehumidifier when the difference between outside and inside humidity is above 10%. Normally there is a fan taking care of it but sometimes the differents gets to high. As there is already a raspberry pi running in the observatory for the weatherstation and the flightradar24 installation we just added the 4 channel relay board ks0212 from keyestudio. Not touching the 220V part we directly used the relay to “press” the TTL switch on the board for 0.5 seconds to turn on and off the dehumidifier. Here are the code snipped we used for this. The control is completely handled via MQTT.

Installing necessary programs and libraries

For the sake of simplicity we used python and the GPIO library wiringpi. Therefore we first install the python development parts and them the python libraries for wiringpi and MQTT. As this is a dedicated hardware installation we don’t use virtualenv and directly install the library as root system wide.

The python program

Again, a very simple python script, basically attaching to a (you need to change the code, there is no config) mqtt server and subscribes itself to a certain topic. Then it waits for messages and cuts off the last part of the topic to identify the relay. The naming convention is based on the relay name printed on the ks0212 pcb. As payload you can send “on“, “off” and “press“. “press” switches the relay on for half a second in order to simulate a button press as we need it for our dehumidifier.

Adding a systemd service

In order to keep the wantabe daemon up and running and also start it automatically at system start we add this service configuration file in “/lib/systemd/system/relayboard.service“:

Activating the service

The following lines activate the service:

Checking the status can be done with:

ks0212 Pinout

If you want to do some hacking with the ks0212 relay board on your own here is the pin mapping table. I used the very cool side for getting the numbers:

Relay WiringPi BCM GPIO Link
J2 7 4 7
J3 3 22 15
J4 22 6 31
J5 25 26 37



Execute the Radio Meteor Observations program on mac os

MeteorLogger Screenshot
MeteorLogger Screenshot

What is it about

Wolfgang Kaufmann wrote an impressive article and even a more impressive software for the hobby radio astronomers. I highly recommend checking out the article and play with the software as there are not so many radio astronomers among the community. His software is written in python with a very clean UI. It directly connects via the computer sound card and grabs the audio signal. I shortly describe here what to install on a Mac OS to get his software up and running.

Where to get it

The software can be downloaded at Unfortunately it is not available on any online repo like github but the source code can be downloaded as a zip file.


The PyAudio package needs some libraries and direct access to the os sound system. Therefore we need it install this audio package outside of python itself

The necessary python libs can be installed via pip. I recommend doing it in a virtual environment

That is all. After installing the python libs the program starts right away


Setting up SDRplay remote on a raspberry pi



I recently bought myself a SDRPlay receiver to play with this technology and maybe build a ground station or meteor scatter detector. The original plan is to setup a receiver on the Motionlab roof with an raspberry pi and send the IQ data via network down to a local server and extract the interesting information. One great software to work remotely with an SDR receiver is the Soapy project.

Install the raspberry pi part

Build system

Install the latest raspberry pi lite version from

Core system

The soapy part consist of 3 parts. The Core system must be installed first.


The SDRplay part consist of two parts one are the proprietary binary libraries from SDRplay itself the the other part is the soapy wrapper for SDRplay.

Binary Libraries

The driver can be downloaded from the SDRplay homepage

The SDRplay Soapy wrapper

Test the Soapy access

Soapy Server for Remote Access

Run the server

If you want to run it as a service have a look here on how to autostart stuff in linux.

How to use travis-ci to check your application code and the smart contract

Travis CI – Build summary

Hyperledger projects code structure

Travis-CI is one of the most used continuous delivery platforms for open source projects. In order to check your hyperledger blockchain application you need to check at least two different languages in the same travis-ci configuration, as your smart contract is written in GOlang and your application most likely in Javascript or Python or whatever(tm).

Lets assume you have a project with:

  • Smart Contract written in GO
  • Backend Server written in Python
  • Frontend written in Javascript (NodeJS)

If you run your hyperledger blockchain for development purpose on Bluemix you will need to compile your code against v0.6. This leads to a problem because you can not specify a branch when you checkout a repository in “go get”. Therefore we need to checkout the code “by hand”. Let us assume your project looks like this:

Each part of the project (smart contract, backend, frontend) is in a separate directory and has a code part and a unit test part. Without getting into details on how to run unit tests for each language we concentrate now on the .travis file.

Configure travis.yml

We have two tests for python (one with 2.7 the other one with the latest nightly build), one for the javascript (no unit test in this example) and the GO part.

Important are lines 29 and 30. Before we run the go build we create the directory for hyperledger and check out manually the official hyperledger code with the v0.6 branch. After that we can normally build the smart contract by calling go build ./



WordPress docker setup with nginx proxy

Setup a wordpress blog on docker with nginx as reverse proxy

docker setup with wordpress, nginx and mysql
Docker setup with wordpress, nginx and mysql containern

My friend und very experienced colleague Niklas Heidloff convinced me to start also a blog with all the geeky things I am doing all day long. In order to make it more interesting for me I decided to host wordpress on my own instead of using wordpress as a service (WaaS ?). Sylwester from pointed me to Vultr for hosting and so here we start. The idea is to have a simple docker setup with 3 containers. One for the Nginx webserver facing the evil internet and proxying the wordpress which is located in the local private docker network. Doing so I can also redirect to other web services (containers) later. Luckily there are already maintained docker container available for all 3 parts, so I only need to customize the nginx container with a dockerfile but can use the two others right as they are.

Install Docker on Ubuntu

Either you go with a docker provider like Bluemix or you get a virtual machine from softlayer or any other provider. In my case I have chosen a virtual server so I had to install docker on Ubuntu LTS. Which is really easy. Basically you add a new repository entry to your apt sources and install latest stable docker packages. There is also a script available on but I don’t feel comfortable to execute a shell script right from the net with root access. But it’s up to you.

wget -qO- | sh

Docker on linux does not contain docker-compose compared to the docker installation for example on mac. Installing docker compose is straightforward. The docker compose script can be downloaded from github here:


Docker-compose takes care of a docker setup containing more than one docker container, including network and also basic monitoring. The following script starts and builds all docker container with nginx, mysql and wordpress. It also exports the volumes on the host file system for easy backup and persistence along docker container rebuilds and monitors if the docker containers are up and running.

Mysql is the first container we bring up with environment variables for the database like username, password and database name. Line 7 takes care to save the database file outside the docker container so you can delete the docker container, start a new one and still have the same database up and running. Point this where you want to have it. In this case in “db” under the same directory. Also make sure you come up with decent passwords.

The second container is wordpress. Same here with the host folder on line 21. Furthermore make sure you have the same user, password and db name configured as in the mysql container configuration.

Last one is nginx as internet facing container. You expose the port 80 here. While you just specify a container in the other two, in this one you configure a Dockerfile and a build context to customize your nginx regarding to the network setup. If you only want to host static files you can add this via volume mounts, but in our case we need to configure nginx itself so we need a customized Dockerfile as described below.

Dockerfile for nginx setup

This dockerfile inherits everything from the latest nginx and copies the default.conf file into it. See next chapter for how to setup the config file.

Nginx config file

Line 2 and 3 configures the port we want to listen on. We need one for ip4 and one for ip6. Important is the proxy configuration in line 8 to 15. Line 11 redirect all calls to “/” (so without a path in the URL) to the server wordpress. As we used docker-compose for it docker takes care to make the address available via the internal DNS server. Line 13-15 rewrites the http header in order to map everything to the different URL, otherwise we would end up with auto generated links in docker pointing to http://wordpress

Start the System

If everything is configured and the docker-compose.yml, default.conf, Dockerfile-nginx and the folders db and wordpress are in the same folder, we can start everything being in this folder with:

The parameter “-d” starts the setup in the background (daemon). For the very first run I would recommend using it without the “-d” parameter to see all debug messages.