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!)
Warning: mysqli::__construct(): Unexpected server respose while doing caching_sha2 auth: 109 in Standard input code on line 22
Warning: mysqli::__construct(): MySQL server has gone away in Standard input code on line 22
Warning: mysqli::__construct(): (HY000/2006): MySQL server has gone away in Standard input code on line 22
MySQL Connection Error: (2006) MySQL server has gone away
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.
docker exec -it blog_wordpress_db_1 bash
mysql -u root -pREALLYEPICSECURE
ALTER USER wordpressuser IDENTIFIED WITH caching_sha2_password BY 'REALLYEPICSECURE';
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 the 4 channel relay board ks0212 to the MQTT universe
We just hacked a trotec dehumidifier for HerwigsObservatory. 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.
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
import paho.mqtt.client as mqtt
def on_connect(self, client, userdata, rc):
def on_message(client, userdata, msg):
m = msg.topic.split("/")
pin = 0
if m[-1] == "j3":
pin = 3
if m[-1] == "j2":
pin = 7
if m[-1] == "j4":
pin = 22
if m[-1] == "j5":
pin = 25
if pin != 0:
if msg.payload == "on":
if msg.payload == "off":
if msg.payload == "press":
if __name__ == "__main__":
mqclient = mqtt.Client(clean_session=True)
mqclient.connect("192.168.2.5", 1883, 60)
mqclient.on_connect = on_connect
mqclient.on_message = on_message
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“:
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.
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.
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.
- language: python
- cd python
- python -m unittest discover -p Test.py
- language: python
- cd python
- python -m unittest discover -p Test.py
- language: node_js
- language: go
- cd go
- mkdir -p $GOPATH/src/github.com/hyperledger
- git -C $GOPATH/src/github.com/hyperledger clone -b v0.6 http://gerrit.hyperledger.org/r/fabric
- go build ./
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 ./
Setup a wordpress blog on docker with nginx as reverse proxy
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 Fablab.berlin 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 get.docker.com 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- https://get.docker.com/ | 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: https://github.com/docker/compose/releases.
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
COPY default.conf /etc/nginx/conf.d/default.conf
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.
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:
docker-compose up --build -d
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.