Adding labels to Docker images is a good practice as this custom metadata permits to organize images by environments, record build information and is very helpful in automation.
This guide will show you 2 ways of how to add custom metadata to Docker images. (more…)
Docker image is built up from a series of layers that represent instructions in the image’s Dockerfile.
Sometimes it may be necessary to show an image layers, their sizes and the instructions they have been created of.
In this note i will show how to list all layers a Docker image is composed of, show their sizes and the instructions from the image’s Dockerfile. (more…)
The good practice is to tag Docker images with useful tags, e.g. version, intended destination (prod or staging), stability or any other information that is useful when deploying the application in different environments.
In this note i will show how to tag Docker images with one or multiple tags during a build.
Also i will show how to tag already existent Docker image and how to change (retag) or remove tags. (more…)
A minimal Docker image based on Alpine Linux has only 5 MB in size, but a lot of tools common for Linux distributions (e.g. curl) are not installed by default.
In this short note i will show how to install curl in Alpine container from the command line.
I will also show how to build an Alpine-based Docker image with curl installed. (more…)
A docker run command is one of the basic commands in a Docker universe as it is used to start containers from Docker images.
In this short note i will show how to start a Docker container in a foreground, in a background or with an interactive shell session of bash or sh from the command line using the docker run command. (more…)
RetroPie, starting from the version 4.6, can be installed on Raspberry Pi 4.
In this note i will show how to download the latest image of RetroPie and how to install it on Raspberry Pi 4 using Raspberry Pi’s Imager in Windows, MacOS and Linux.
Additionally, i will show how to burn the RetroPie’s image on a microSD card using the dd command from the Linux command line. (more…)
If you are going to use a Raspberry Pi headless (without a monitor), you should know that for security reasons the SSH server in Raspbian is disabled by default.
In order to connect to the headless Raspberry Pi, you should enable SSH in advance and this can be done even before the first boot.
In this small note i will show how to enable SSH in Raspbian if the Raspberry Pi is without a monitor and keyboard. (more…)
Most of the operating systems for Raspberry Pi have default password for accessing RPi using SSH or VNC.
In Raspberry Pi OS (formerly Raspbian), for example, the default username is pi and the default password is raspberry, but this is not a standard for the most of the other distributions.
Below you will find a table with default logins and default passwords for the most popular RPi’s distributions.
Also i will show how to change a password in Raspberry Pi for the current user or for any other user, including root. (more…)
To connect to a Raspberry Pi using SSH or VNC, you need to know the Pi’s IP address.
If you use the Raspberry Pi with a monitor, you can check the Pi’s IP from the command line (terminal) by executing the hostname -I command.
Without a monitor and keyboard (headless) you can find the Raspberry Pi’s IP if you connect it to LAN (Local Area Network).
In this note i will show how to find the Raspberry Pi’s IP on network. (more…)
Journalctl is a command line tool in Linux for querying and displaying logs from journald, systemd’s logging service.
In this note i will show how to use journalctl to tail systemd service logs (display last 100 lines or follow) and how to show logs for particular time rages: today’s logs, previous boot logs or systemd service logs for specific date and time. (more…)