Docker

Containers: Docker

Docker use cases

Docker creation

How to create Docker Images with a Dockerfile
Intro Guide to Dockerfile Best Practices
Docker: Use multi-stage builds
Multistage builds are useful to anyone who has struggled to optimize Dockerfiles while keeping them easy to read and maintain.
How to modify the configuration file when the Docker container fails to start normally?
Microcontainers – Tiny, Portable Docker Containers
How to Create a Dockerfile for a Python Application
A step-by-step guide to creating a Python container.

Docker operation

Docker Compose

Docker Swarm

Docker Swarm: Deploying a 3-Tier Architecture

Docker installation

Docker Machine

Docker Machine Overview
Docker Machine is a tool that lets you install Docker Engine on virtual hosts, and manage the hosts with docker-machine commands. You can use Machine to create Docker hosts on your local Mac or Windows box, on your company network, in your data center, or on cloud providers like Azure, AWS, or Digital Ocean.
Machine was the only way to run Docker on Mac or Windows previous to Docker v1.12. Starting with the beta program and Docker v1.12, Docker Desktop for Mac and Docker Desktop for Windows are available as native apps and the better choice for this use case on newer desktops and laptops. We encourage you to try out these new apps. The installers for Docker Desktop for Mac and Docker Desktop for Windows include Docker Machine, along with Docker Compose.
Docker Desktop for Windows uses Microsoft Hyper-V for virtualization, and Hyper-V is not compatible with Oracle VirtualBox. Therefore, you cannot run the two solutions simultaneously. But you can still use docker-machine to create more local VMs by using the Microsoft Hyper-V driver.The prerequisites are:
- Have Docker Desktop for Windows installed, and running (which requires that virtualization and Hyper-V are enabled, as described in What to know before you install Docker Desktop for Windows).
- Set up the Hyper-V driver to use an external virtual network switch See the Docker Machine driver for Microsoft Hyper-V topic, which includes an example of how to do this.

Docker: image customization

Dockerize an SSH service
SSH into a Docker Container
There are several reasons why you may not want or need to enable SSH on a Docker container. First, you often don’t need to run SSHd in Docker to do stuff you’d normally use SSH for. You can access logs, restart services and browse a container file system with docker attach or docker exec.
Second, it goes against the philosophy of Docker containers. A container should do exactly one thing.
Finally, it may be a security risk. Exposing an additional means of accessing a container certainly increases the attack surface. You may also need to deal with password / key management.
Running SSH in an Alpine Docker Container
Run multiple services in a container
Building Minimal Docker Containers for Python Applications
Putting Bottle in a Container: Docker and Bottle
SR-IOV in Docker containers

Modification of a service configuration file in a container

Copy the configuration files in the container to the host:
# Syntax: docker CP < container name / container ID >: < path of configuration file in container > < path to be copied to host > $ docker cp mysql:/etc/mysql/mysql.conf.d/mysqld.cnf ~/mysqld.cnfModify the configuration file in the host. Then copy the modified configuration file back into the container:# Syntax: docker CP < path of configuration file in host > < container name / container ID >: < path of configuration file in container > $ docker cp ~/mysqld.cnf mysql:/etc/mysql/mysql.conf.d/mysqld.cnfRestart the container.

Docker performance

Docker and time

Docker migration

Live migration, la migrazione dei container su neen Jelastic PaaS

Docker and media streaming

SysAdm: FFmpeg streaming with Docker-based Network Function
GStreamer in Docker = overlays not working
I need to stream a video from a server to a client, with a clock overlay. The server must be inside a Docker image. Here is the server command:

gst-launch-1.0 \
v4l2src device=/dev/video0 \
! videorate ! videoscale \
! clockoverlay shaded-background=true font-desc="Sans 38" \
! video/x-raw,format=I420,width=640,height=360,framerate=25/1 \
! jpegenc ! rtpjpegpay \
! udpsink host=localhost port=5000

And here is the client:

gst-launch-1.0 -v \
udpsrc port=5000 \
! application/x-rtp, encoding-name=JPEG, framerate=25/1 \
! rtpjpegdepay ! jpegdec ! videoconvert ! ximagesink

Solution: I just needed to install gstreamer1.0-x as well.

Docker in Windows

Get started with Docker Machine and a local VM
Boot2Docker is a lightweight Linux distribution made specifically to run Docker containers. It runs completely from RAM, is a ~45MB download and boots quickly.
Boot2Docker is officially deprecated and unmaintained. It is recommended that users transition from Boot2Docker over to Docker Desktop instead (especially with the new WSL2 backend, which supports Windows 10 Home).

Docker in Windows WSL2

Docker container and ARM architectures

How To Build Docker Images For Apple Silicon (Aka M1 Chip)

When building docker images on an M1, you’ll need to enable an experimental feature and then can build images for both amd64 (x86) and arm64 (M1)

# The usual way on intel
docker build ---push -t mbari/polynote:latest .# On Apple Silicon
docker buildx build --platform linux/amd64,linux/arm64 --push -t mbari/polynote:latest .

How to Actually Deploy Docker Images Built on M1 Macs With Apple Silicon
Come creare immagini Docker x86 (e altre!) Su un Mac M1
Create docker image on Apple Silicon M1 Mac
Minio on ARM (Alex Ellis on github)
Minio is an S3 compatible object storage server written in Go. You can store anything you want and it even runs on the Raspberry Pi. I’ve built a special Dockerfile to enable Docker to bring Minio to the Pi and ARM devices.
lakhansamani/docker-demo (GitHub)
This repository is used to demonstrate how you can build linux/amd64 docker images on m1 chip mac books. It is a simple repository demonstrating the Hello World in Golang
Multi-arch build and images, the simple way
“Build once, deploy anywhere” is really nice on the paper but if you want to use ARM targets to reduce your bill, such as Raspberry Pis and AWS A1 instances, or even keep using your old i386 servers, deploying everywhere can become a tricky problem as you need to build your software for these platforms. To fix this problem, Docker introduced the principle of multi-arch builds and we’ll see how to use this and put it into production.
Creating An Alpine Image With Ansible

Useful Docker containers

juliopdx/netauto
Used to build automation image.
wbitt/network-multitool
Alpine based multi-arch multi-tool for container network troubleshooting. (Formerly owned by Praqma)
prantlf/alpine-make-gcc
Docker image with make, gcc, binutils, autoconf, musl and other tools for compiling packages on Alpine Linux.
A simple docker container with static binaries for capsh, getcap, setcap
This makes it easy to work with capabilities in docker containers.
Available on Docker Hub:
https://hub.docker.com/r/scionproto/docker-caps
Ryu DockerFile
Just a dockerfile to run ryu controller in a container. Uses python 3.8 and alpine.
ergw/ergw-docker-base
This repository contains the Dockerfile to build a base container image to run erlang-applications for erGW. The image is autmatically build in docker hub.