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Docker howto

204 · cloud ·

Last update
2019-07-08

2019
07-08

« — »

Installation on debian

# check system compatibility
wget -q -O - https://raw.githubusercontent.com/docker/docker/master/contrib/check-config.sh | \
  bash | tee docker-check.txt

# install docker: key, repo, packages
apt-get install apt-transport-https ca-certificates curl gnupg2 software-properties-common
curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add -

# echo "deb [arch=amd64] https://download.docker.com/linux/debian stretch stable" > /etc/apt/sources.list.d/docker-ce.list # armhf @ raspi
add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/debian $(lsb_release -cs) stable" # armhf @ raspi

apt-get update && apt-get install docker-ce

# allow user to use docker
usermod -aG docker username

# test installation
docker version
docker info

# run a simple test image
docker run hello-world

See also post install for troubleshooting dns/network/remote access.

On raspberry pi just use curl -sSL https://get.docker.com | sh (repo not working).

Creating an image (ref, best practices)

touch Dockerfile # and fill it
docker build -t test-myimg . # create the image with a tag

# test run image
docker run -p 4000:80    test-myimg
docker run -it test-myimg /bin/bash

# run image detached/on background
docker run -p 4000:80 -d --name tmi test-myimg
docker container ls -a
docker container stop <container_id>
docker container start -i tmi # restart container

Interact (ref)

# run interactive shell into debian image (temporary)
docker run --name prova --rm -it debian /bin/bash 

# run interactive shell into debian image
docker run -it debian /bin/bash 

apt-get update

apt-get install -y dialog nano ncdu
apt-get install -y locales

localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8
echo "LANG=en_US.utf8" >> /etc/environment

rm -rf /var/lib/apt/lists/*

docker commit e2b7329257ba myimg:v1

docker run --rm -it myimg:v1 /bin/bash

# run a command in a running container
docker exec -ti a123098734e bash -il

docker stop a123098734e
docker kill a123098734e

Save & restore

docker save imgname | gzip > imgname.tgz
zcat imgname.tgz | docker load

# flatten image layers (losing Dockerfile)
docker export <id> | docker import - imgname:tag

Registry - Image repository

# push image to gitlab registry
docker login registry.gitlab.com
docker tag test-myimg registry.gitlab.com/username/repo:tag # add new tag...
docker rmi test-myimg # ...and remove the old tag
docker push registry.gitlab.com/username/repo:tag

DockerHub official base images links: debian, ruby, rails, redis, nginx.

Available free registry services:

Name	# Priv/Pub	Notes
gitlab	inf/ND	1 prj x registry
treescale	inf/inf	max 500 pulls & 50GB
canister	20/ND	very good service
docker hub	1/inf	perfect

Running `arm` image on `x86`

# https://ownyourbits.com/2018/06/27/running-and-building-arm-docker-containers-in-x86/
apt-get install qemu-user-static

docker run \
  -v /usr/bin/qemu-arm-static:/usr/bin/qemu-arm-static \
  -e LANG=en_US.utf8 -ti --name myarmimg arm32v7/debian:wheezy

[...]

docker commit myarmimg myarmimg

docker container prune -f

docker run \
  -v /usr/bin/qemu-arm-static:/usr/bin/qemu-arm-static \
  -ti --rm --name myarmimg \
  myarmimg /bin/bash -il

Composer (ref, dl) - Services

# docker-compose.yml
version: "3"
services:
  web:
    image: username/repo:tag
    deploy:
      replicas: 5
      resources:
        limits:
          cpus: "0.1"
          memory: 50M
      restart_policy:
        condition: on-failure
    ports:
      - "4000:80"
    networks:
      - webnet
networks:
  webnet:

# install docker-compose
curl -L  -o /usr/local/bin/docker-compose https://github.com/docker/compose/releases/download/1.24.0-rc1/docker-compose-`uname -s`-`uname -m`
chmod 755 /usr/local/bin/docker-compose

docker swarm init

docker stack deploy --with-registry-auth -c docker-compose.yml getstartedlab
docker service ls
docker service ps getstartedlab_web # or docker stack ps getstartedlab

# change the yml file and restart service
docker stack deploy --with-registry-auth -c docker-compose.yml getstartedlab
docker service ps getstartedlab_web
docker container prune -f

# stop & destroy service
docker stack rm getstartedlab
docker container prune -f

# leave the swarm
docker swarm leave --force

Machine (ref, dl) - SWARM/Provisioning

Remember to update the host firewall: open port 2376 and do not apply rate limits on port 22.

On the fish shell you can install the useful omf plugin-docker-machine to easily select the current machine.

Without an official supported driver we can use the generic one. Install docker-ce on your worker nodes and then in your swarm manager host:

# install docker-machine
curl -L -o /usr/local/bin/docker-machine https://github.com/docker/machine/releases/download/v0.16.1/docker-machine-`uname -s`-`uname -m`
chmod 755 /usr/local/bin/docker-machine

# setup each VMs (this creates and shares the certificates for a secure
# connetion between your client and the daemon runnig on the server)
ssh-copy-id -i ~/.ssh/id_rsa user@ww.xx.yy.zz
docker-machine create --driver generic --generic-ssh-key ~/.ssh/id_rsa \
  --generic-ip-address=ww.xx.yy.zz myvm1

ssh-copy-id -i ~/.ssh/id_rsa user@ww.xx.yy.kk
docker-machine create --driver generic --generic-ssh-key ~/.ssh/id_rsa \
  --generic-ip-address=ww.xx.yy.kk myvm2

docker-machine ls

# run a command via ssh in a VM
docker-machine ssh myvm1 "ls -l"                 # use internal SSH lib
docker-machine --native-ssh ssh myvm1 "bash -il" # use system SSH lib

# set env to run all docker commands remotely on a VM
eval $(docker-machine env myvm1) # on bash
docker-machine use myvm1         # on fish + omf plugin-docker-machine

# set VM1 to be a swarm manager
docker-machine use myvm1
docker swarm init # --advertise-addr ww.xx.yy.zz
docker swarm join-token worker # get token for adding worker nodes

# set VM2 to join the swarm as a worker
docker-machine use myvm2
docker swarm join --token SWMTKN-xxx ww.xx.yy.zz:2377

# check cluster status on your local machine...
docker-machine ls
# ...or on the manager node
docker-machine use myvm1
docker node ls

# locally login on your registry...
docker-machine unset
docker login registry.gitlab.com
# ...then deploy the app on the swarm manager
docker-machine use myvm1
docker stack deploy --with-registry-auth -c docker-compose.yml getstartedlab
docker service ls
docker service ps getstartedlab_web

# access cluster from any VM's IP
curl http://ww.xx.yy.zz:4000
curl http://ww.xx.yy.kk:4000

# eventually re-run "docker stack deploy ..." to apply changes

# undo app deployment
docker-machine use myvm1
docker stack rm getstartedlab

# remove the swarm
docker-machine ssh myvm2 "docker swarm leave"
docker-machine ssh myvm1 "docker swarm leave --force"

Stack / Deploy application

# docker-compose.yml
version: "3"
services:
  web:
    image: username/repo:tag
    deploy:
      replicas: 5
      restart_policy:
        condition: on-failure
      resources:
        limits:
          cpus: "0.1"
          memory: 50M
    ports:
      - "80:80"
    networks:
      - webnet
  visualizer:
    image: dockersamples/visualizer:stable
    ports:
      - "8080:8080"
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock"
    deploy:
      placement:
        constraints: [node.role == manager]
    networks:
      - webnet
  redis:
    image: redis
    ports:
      - "6379:6379"
    volumes:
      - "/home/docker/data:/data"
    deploy:
      placement:
        constraints: [node.role == manager]
    command: redis-server --appendonly yes
    networks:
      - webnet
networks:
  webnet:

docker-machine use myvm1
docker-machine ssh myvm1 "mkdir ./data" # create redis data folder

# run stack / deploy app
docker stack deploy -c docker-compose.yml getstartedlab
docker stack ps getstartedlab

# show deployed services and restart one
docker service ls
docker service update --force getstartedlab_web

firefox http://<myvm1-ip>:8080/ # docker visualizer
redis-cli -h <myvm1-ip>         # interact with redis

docker stack rm getstartedlab

Container-Host user remapping

You can map container users to the host ones for greater security.

put myuser:100000:65536 in /etc/subuid and /etc/subgid, this defines the mapping id range 100000-165535 available to the host user myuser
configure docker daemon to use the remapping specified for myuser:
1 2
echo '{ "userns-remap": "myuser" }' > daemon.json systemctl restart docker
note that all images will reside in a /var/lib/docker subfolder named after myuser ids
now all your container user/group ids will be mapped to 100000+id on the host

You can write up to 5 ranges in sub* files for each user, in this example we set identical ids for users 0-999 and map ids >=1000 to id+1:

1 2	myuser:0:1000 myuser:1001:65536

Terms:

service = containers that only runs one/same image,
task = a single container running in a service,
swarm = a cluster of machines running Docker,
stack = a group of interrelated services orchestrated and scalable, defining and coordinating the functionality of an entire application.

Source: tutorial, overview, manage app data, config. daemon, config. containers,

Source for user mapping: docker docs, jujens.eu, ilya-bystrov

Useful tips: cleanup, network host mode for nginx to get client real IP, limit ram/cpu usage

~~~ * ~~~

Git manage branches

377 · cloud ·

Git

HowTo

Last update
2019-07-08

2019
07-08

« — »

git checkout -b <branch>          # create branch
git push -u origin <branch>       # push branch to remote

# pull the new branch from another pc:
git fetch                         # download all data
git branch -v -a                  # shows avaiable branches
git checkout <branch>

# delete branch
git push origin :<branch>         # remote
git branch -d <branch>            # local

# rename branch
git branch -m old-name new-name       # local
git push -u origin :old-name new-name # remote

~~~ * ~~~

Fare il gelato senza gelatiera

60 · cloud ·

Dolci

Ricette

Last update
2019-07-02

2019
07-02

« — »

In ambo le ricette è possibile inserire un sapore a piacere, ad esempio:

cacao amaro
scaglie/gocce di cioccolato
amarene sciroppate
sciroppo preferito
granella di pistacchi

Ricetta rapida (senza mescolamenti intermedi)

Ingredienti:

500ml di panna fresca
350gr di latte condensato

Procedimento:

Mescolare tutti gli ingredienti con uno sbattitore e mettere in frigo per almeno 2 ore

Ricetta allo yoghurt (con mescolamenti intermedi)

Ingredienti:

250ml yogurt greco intero
200ml panna fresca
150gr zucchero

Procedimento:

NB: Usare ingredienti e contenitori freddi da frigo, contenitore finale da freezer.

Montare a parte la panna con uno sbattitore
Amalgamare yogurt e zucchero
Unire alla panna senza farla smontare (sbattitore a bassa velocità)
Mettere in freezer per 4 ore mescolando ogni 30 minuti

Fonte: Blog Giallozafferano per gelato yogurt, latte condensato 1 e 2

~~~ * ~~~

youtube-dl usage

186 · cloud ·

Last update
2019-07-02

2019
07-02

« — »

# download/upgrade
curl -L -o ~/bin/youtube-dl https://yt-dl.org/downloads/latest/youtube-dl

# build from source repo
git clone https://github.com/ytdl-org/youtube-dl.git
cd youtube-dl
make clean && make

# to parse a playlist use "--yes-playlist url" or simply "playlist_id"

# downoload a playlist audio only
youtube-dl -i -o "%(title)s.%(ext)s" \
  -f bestaudio --extract-audio --audio-format mp3 --audio-quality 2 \
  <playlist_id>

# download a specific combination of audio and video in a single file
youtube-dl -F <url> # detect desired format codes
youtube-dl --merge-output-format mkv -f <code1>+<code2> <url>

Source: youtube-dl hp, stackoverflow.com, askubuntu.com

~~~ * ~~~

Windows tabbed console

44 · cloud ·

Terminal

Tools

Windows

Last update
2019-06-21

2019
06-21

«ConsoleZ is a fork of Console2
+ optional MidnightCommander config»

My ConsoleZ setup with git bash for windows

download and install git bash
download and install ConsoleZ
gunzip and copy the attached config file to /c/Users/user_name/AppData/roaming/Console to have:
- default git bash session
  - icon: C:\Program Files\Git\git-bash.exe
  - shell: %windir%\system32\cmd.exe /c ""C:\Program Files\Git\bin\sh.exe" --login -i"
- LucidaConsole font with ClearType
- 10000 rows buffer size
- auto save position and size
- shortcuts:
  - Ctrl+Shift+T to create new tab
  - Shift+LArr/RArr to switch tab left/right
  - Ctrl+# to switch to tab number #
  - Ctrl+Alt+S to rename tab
  - Ctrl+0/+/- to zoom font
  - Ctrl+Ins / Shift+Ins to copy/paste
  - Shift+Click&Move to select and copy text
  - Ctrl+Click&Move to move window
  - MiddleClick (bt#3) to paste

Midnight commander setup

download MC for windows and install it into C:\Programmi\mc
append this in $HOME/.bash_profile:

1 2	alias mc=". $HOME/bin/mc-wrapper.sh" export EDITOR=/usr/bin/nano

create $HOME/bin/mc-wrapper.sh:

MC_USER=`id | sed 's/[^(]*(//;s/).*//'`
MC_PWD_FILE="${TMPDIR-/tmp}/mc-$MC_USER/mc.pwd.$$"
/c/Programmi/mc/mc -P "$MC_PWD_FILE" "$@"

if test -r "$MC_PWD_FILE"; then
  MC_PWD="`cat "$MC_PWD_FILE"`"
  if test -n "$MC_PWD" && test -d "$MC_PWD"; then
    cd "$MC_PWD"
  fi
  unset MC_PWD
fi

rm -f "$MC_PWD_FILE"
unset MC_PWD_FILE
unset MC_USER

MC > Options > Config > Use internal editor

Source: ConsoleZ, old Console2

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Listing posts

Installation on debian

Creating an image (ref, best practices)

Interact (ref)

Save & restore

Registry - Image repository

Running arm image on x86

Composer (ref, dl) - Services

Machine (ref, dl) - SWARM/Provisioning

Stack / Deploy application

Container-Host user remapping

Ricetta rapida (senza mescolamenti intermedi)

Ricetta allo yoghurt (con mescolamenti intermedi)

My ConsoleZ setup with git bash for windows

Midnight commander setup

Running `arm` image on `x86`