Category: Technology

Content about technology in the broadest sense of the definition.

Installing the UniFi Network Application on Raspberry Pi

Unfortunately MongoDB does not have an ARM64 bit package for Raspberry Pi yet, so I’m installing this on a Raspberry Pi with a 32-bit (Debian-based) Raspberry Pi OS:

sudo apt update && sudo apt full-upgrade -y && sudo apt autoremove -y && sudo apt-get autoclean -y
sudo apt install openjdk-8-jre-headless jsvc libcommons-daemon-java -y
sudo apt install haveged -y
sudo apt install mongodb-server mongodb-clients -y

echo 'deb https://www.ui.com/downloads/unifi/debian stable ubiquiti' | sudo tee /etc/apt/sources.list.d/100-ubnt-unifi.list
sudo wget -O /etc/apt/trusted.gpg.d/unifi-repo.gpg https://dl.ui.com/unifi/unifi-repo.gpg
sudo apt update && sudo apt install unifi -y

Go to your UniFi Controller via the IP address and port, for example: https://10.1.0.5:8443

Configure a fixed IP address on a Hue Bridge

To configure a fixed IP address on the HUE bridge, you need to browse to the bridge using:

http://x.x.x.x/api/[bridge-user]/config

Use a HTTP PUT command to configure the IP address and use as body:

{ "ipaddress":"[new-ip]", "dhcp":false, "netmask": "[network-netmask]", "gateway": "[network-gateway]" }

Alternatively, you can use the HUE app and change the network settings in the bridge configuration.

Screenshot of the fixed IP address configuration in the Hue app.

Updating Eclipse Ditto

Stop running containers using docker-compose and remove the containers.

docker-compose stop
docker rm docker_nginx_1
docker rm docker_connectivity_1
docker rm docker_gateway_1 
docker rm docker_things_1 
docker rm docker_concierge_1 
docker rm docker_things-search_1
docker rm docker_policies_1
docker rm docker_mongodb_1
docker rm docker_swagger-ui_1 
docker system prune -a

Download the latest Ditto zip from Github and re-run docker-compose.yaml.

This folder contains an example docker-compose.yml which can be used to start Eclipse Ditto with its backing Database – MongoDB – and a reverse proxy – nginx – in front of the HTTP and WebSocket API.

Eclipse Ditto :: Docker

Source: https://github.com/eclipse/ditto/blob/master/deployment/docker/README.md

Configure nginx

The nginx’s configuration is located in the nginx.conf file and contains a “Basic authentication” for accessing the HTTP and WebSocket API. The users for this sample authentication are configured in the nginx.httpasswd file also located in this directory.

In order to add a new entry to this file, use the “openssl passwd” tool to create a hashed password:

openssl passwd -quiet
 Password: <enter password>
 Verifying - Password: <enter password>

Append the printed hash in the nginx.httpasswd file placing the username who shall receive this password in front like this:

ditto:A6BgmB8IEtPTs

Configuration of the services

You may configure each service via passing variables to the java VM in the entrypoint section for each service.

...
# Alternative approach for configuration of the service
command: java -Dditto.gateway.authentication.devops.password=foobar -jar starter.jar

To get a list of available configuration options you may retrieve them from a running instance via:

# Substitute gateway with the service you are interested in
curl http://devops:foobar@localhost:8080/devops/config/gateway/?path=ditto

Or by going through the configuration files in this repository e.g. /services/gateway/starter/src/main/resources/gateway.conf.

Start Eclipse Ditto

docker-compose up -d

Check the logs after starting up:

docker-compose logs -f

Stop Eclipse Ditto

docker-compose down

Installing .NET 6 on a Raspberry PI (Debian)

Create a folder, for example /app/dotnet6, and assign ownership to the right user:

sudo mkdir /app/dotnet6
sudo chown -R pi /app/

Download the .NET 6 SDK at Microsoft:

wget https://download.visualstudio.microsoft.com/download/pr/adcd9310-5072-4179-9b8b-16563b897995/15a7595966f488c74909e4a9273c0e24/dotnet-sdk-6.0.100-linux-arm64.tar.gz

Extract the tar.gz file in the /app/dotnet6 directory:

sudo tar zxf dotnet-sdk-6.0.100-linux-arm64.tar.gz -C /app/dotnet6

Test the .NET6 installation by browsing to the installation directory and execute the dotnet –info command:

cd /app/dotnet6
./dotnet --info
.NET SDK (reflecting any global.json):
 Version:   5.0.101
 Commit:    d05174dc5a

Runtime Environment:
 OS Name:     debian
 OS Version:  10
 OS Platform: Linux
 RID:         debian.10-arm64
 Base Path:   /app/dotnet/sdk/5.0.101/

Host (useful for support):
  Version: 5.0.1
  Commit:  b02e13abab

.NET SDKs installed:
  5.0.101 [/app/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 5.0.1 [/app/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 5.0.1 [/app/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET runtimes or SDKs:
  https://aka.ms/dotnet-download

Increasing the maximum upload file size in WordPress

Locate php.ini. For Debian this file is located in:

/etc/php/7.4/apache2

Search for the following configuration lines (in nano use CTRL+W for search) and replace the existing configuration values with acceptable values.

max_execution_time = 60
memory_limit = 128M
post_max_size = 64M
upload_max_filesize = 64M
max_input_time = 60
file_uploads = On
safe_mode = Off

Locate .htaccess file in the root of your wordpress directory and add or adjust:

php_value upload_max_filesize 64M
php_value post_max_size 128M
php_value memory_limit 256M
php_value max_execution_time 300
php_value max_input_time 300

When you open the media library in WordPress and try to upload a file it should reflect the maximum configured upload file size:

InfluxDB update from 1.8.6-1 to 1.8.7-1

Upgrading InfluxDB failed. For some reason the update caused permission issues with the start-up script:

usr/lib/influxdb/scripts/influxd-systemd-start.sh

When I gave this file permission to execute the InfluxDB service started again:

chmod +x /usr/lib/influxdb/scripts/influxd-systemd-start.sh

Then, the next problem appeared: systemctl didn’t recognise that the service was actually running: it was stuck in the state “activating”. Then I found an article on serverfault that described my problem.

I’m running InfluxDB on Debian so couldn’t apply the suggestion solution, but needed to interpret this a bit. I edited the file:

/etc/systemd/system/influxd.service

I changed the type to simple, as indicated in this code sample:

[Unit]
Description=InfluxDB is an open-source, distributed, time series database
Documentation=https://docs.influxdata.com/influxdb/
After=network-online.target

[Service]
User=influxdb
Group=influxdb
LimitNOFILE=65536
EnvironmentFile=-/etc/default/influxdb
ExecStart=/usr/lib/influxdb/scripts/influxd-systemd-start.sh
KillMode=control-group
Restart=on-failure
Type=simple
PIDFile=/var/lib/influxdb/influxd.pid

[Install]
WantedBy=multi-user.target
Alias=influxd.service

Check the disk space consumption of a Linux directory

Today, one of my virtual systems ran out of disk space. To find the root cause I needed to find the directory that was filling up. Using the right parameters, the du command returns a list of directories and their disk space consumption.

du -hc --max-depth=0 /var

For example:

root@DB152:/# du -hc --max-depth 1 /var
704K    /var/tmp
4.0K    /var/mail
23M     /var/log
1.1M    /var/backups
4.0K    /var/local
3.2G    /var/lib
20K     /var/spool
734M    /var/cache
4.0K    /var/opt
3.9G    /var
3.9G    total

Removing files of a certain type recursively:

find . -name "*json.log" -type f -delete

Clearing (system) log files:

truncate /var/log/* --size 0