Programming

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====== Docker ======
===== Fast use =====
=== Mongo ===

**Usar e instalar la imagen de mongo mapeando el puerto 27017 y los datos en ''/data/db''**

<code>
docker run --rm -d -v /home/alfred/tmp/data:/data/db -v /tmp:/tmp -p 27017:27017 --name mongo mongo
</code>

=== MySql ===

**Usar e instalar la imagen de mysql mapeando los datos en ''/data/db'' con password ''the_pass''**
<code>
docker run -v /home/alfred/tmp/data:/data/db -p 3306:3306 -e MYSQL_ROOT_PASSWORD=the_pass mysql
</code>
Lo mismo que el anterior pero usando la versión 8.0:
<code>
docker run -v /home/alfred/tmp/data:/data/db -p 3306:3306 -e MYSQL_ROOT_PASSWORD=the_pass -d mysql:8.0
</code>
To access: ''mysql -u root -h 127.0.0.1 -p''
=== Postgres ===
<code>
sudo docker run -p 5432:5432 -v /home/alfred/tmp/postgresdata:/var/lib/postgresql/data -e POSTGRES_PASSWORD=mysecretpassword postgres

docker run -d -p 5432:5432 -e POSTGRES_PASSWORD=mysecretpassword postgres:9.4
</code>

=== Php ===
<code>
sudo docker run -p 8000:80 -v /home/alfred/php/:/var/www/html php:7.0-apache
</code>
Tendrás que añadir un fichero ''.htaccess'' con el siguiente contenido:
<code>
allow from all
</code>

==== Creación de un docker basado en lo que ya tienes ====
1. Crea un archivo ''Dockerfile'' y añade:
<code>
FROM php:7.0-apache
</code>
2. Haz:
<code>
$ sudo build -t my-php
</code>
3. Ejecuta:
<code>
$ sudo docker run -d -p 8000:80 -v /home/alfred/php/:/var/www/html my-php
</code>
----

===== Install =====

  * https://docs.docker.com/engine/installation/linux/ubuntulinux/
  * https://docs.docker.com/machine/install-machine/


Para instalarlo en un server virtual, este ha de ser KVM.
===== How to use it =====

**Containers** are completely self-contained machine, for all intents and purposes it has its own OS, its own file system and anything else you would expect to find in a virtualised machine. But the catch is that a container only runs one program†. For example you may have a MySQL server running in a container and Redis running in a separate container.

Each container can have directories (zero or more) mounted to it from the host. For example if you were running an Apache web server container you would not load the source files onto the container itself. Rather you would mount a directory of the host operating system (containing the files for the web server) to a directory of the container, like:

''/Users/elliot/Development/mywebsite -> /var/www/html''

This makes the containers (and images) **stateless**. Containers can be restarted and images can be destroyed without affecting the application. It also makes the images much smaller and reusable. Another advantage is that several containers can share the same mounted directory.

Usually you will have several containers for other services like a database, web service, background tasks, etc. For this we use the** docker-compose** command.

docker-compose uses a very simple YAML file to build multiple containers. Each container can have its own Dockerfile that customises the individual container but docker-compose will build all the containers and put them into the same virtual network.

Containers that are built with docker-compose are put into the same virtual network

**Images** are a snapshot of the file system, however they are always based on a another image.

A **Dockerfile** is a text file (usually held in the root of your project) that has the steps required to build an image. This is akin to the bash script that you would use to install software or setup environment variables. A Dockerfile looks like this:

<code>
FROM php:7.0-apache
COPY config/php.ini /usr/local/etc/php/
ENV APP_ENV dev
</code>

Each line is a command. The first line is always a FROM command that specifies the base image which we build upon. Each step creates a new image, but each image only contains the changes since the last snapshot (previous command).

To run a Docker container, you:
  * create a new (or start an existing) Docker virtual machine
  * switch your environment to your new VM
  * use the docker client to create, load, and manage containers
Once you create a machine, you can reuse it as often as you like. Like any VirtualBox VM, it maintains its configuration between uses.


[[https://hub.docker.com/|Docker hub]] is a repository of Docker Images created by the community.

==== Things to know ====

  * A docker container exits when its main process finishes. 
===== Docker machine =====
The general idea of docker-machine is to give you tools to create and manage Docker clients. This means you can easily spin up a virtual machine and use that to run whatever Docker containers you want or need on it.

What’s the difference between Docker Engine and Docker Machine?

When people say “Docker” they typically mean Docker Engine, the client-server application made up of the Docker daemon, a REST API that specifies interfaces for interacting with the daemon, and a command line interface (CLI) client that talks to the daemon (through the REST API wrapper). Docker Engine accepts docker commands from the CLI, such as docker run <image>, docker ps to list running containers, docker images to list images, and so on.

Docker Machine is a tool for provisioning and managing your Dockerized hosts (hosts with Docker Engine on them). Typically, you install Docker Machine on your local system. Docker Machine has its own command line client docker-machine and the Docker Engine client, docker. You can use Machine to install Docker Engine on one or more virtual systems. These virtual systems can be local (as when you use Machine to install and run Docker Engine in VirtualBox on Mac or Windows) or remote (as when you use Machine to provision Dockerized hosts on cloud providers). The Dockerized hosts themselves can be thought of, and are sometimes referred to as, managed “machines”.



The basic execution of docker-machine is:
<code>
docker-machine create --driver virtualbox default
</code>
This will create your machine and output useful information on completion. The machine will be created with 5GB hard disk, 2 CPU's and 4GB of RAM:
<code>
$ docker-machine create development --driver virtualbox --virtualbox-disk-size "5000" --virtualbox-cpu-count 2 --virtualbox-memory "4096"
</code>

If you are using the virtualbox driver and you'ld like to forward a port to your machine, you need to do it from VirtualBox, so that they are accessible on your host machine.

<code>
VBoxManage controlvm "development" natpf1 "tcp-port8000,tcp,,8000,,8000";
</code>

There are some basic actions for a docker-machine:

<code>
$ docker-machine start development
$ docker-machine stop development
$ docker-machine ls
</code>

You can also generate environment variables:
<code>
$ docker-machene env development
</code>

Or access to it by ssh:
<code>
$ docker-machine ssh development
</code>

To know its ip:
<code>
$ docker-machine ip default
</code>

To list all the machines that exists:
<code>
$ docker-machine ls
</code>
==== docker-machine env ====

  * https://docs.docker.com/machine/reference/env/

Set environment variables to dictate that docker should run a command against a particular machine.

docker-machine env machinename will print out export commands which can be run in a subshell. Running docker-machine env -u will print unset commands which reverse this effect.

Set y Unset the environment variables:
<code>
$ env | grep DOCKER
$ eval "$(docker-machine env dev)"
$ env | grep DOCKER
DOCKER_HOST=tcp://192.168.99.101:2376
DOCKER_CERT_PATH=/Users/nathanleclaire/.docker/machines/.client
DOCKER_TLS_VERIFY=1
DOCKER_MACHINE_NAME=dev
$ # If you run a docker command, now it will run against that host.
$ eval "$(docker-machine env -u)"
$ env | grep DOCKER
$ # The environment variables have been unset.
</code>

==== Docker machine drivers ====

When you install Docker Machine, you get a set of drivers for various cloud providers (like Amazon Web Services, Digital Ocean, or Microsoft Azure) and local providers (like Oracle VirtualBox, VMWare Fusion, or Microsoft Hyper-V).

For creating a machine without a driver:
<code>
$ docker-machine create --url=tcp://50.134.234.20:2376 custombox
</code>
===== Docker commands =====
Using the command ''docker'' with the next parameters you can...

  * ''images'', list images
  * ''rm'' remove containers
  * ''rmi'' remove images
  * ''start'', ''stop'' ''pause'', ''unpause'', change the container state.
  * ''ps'', list containers. ''-a'' to view all, active an inactive. -l to view the lastest.

==== run ====

To run the image nginx:
<code>
 $ docker run -d -p 80:8000 nginx
</code>

  * -d , runs in background.
  * -p 80:8000, links its port 8000 with the 80, so you can access to the 80 and will see what is returning on the 8000.

When we do something like this...
<code>
docker run -it ubuntu
docker run -it java  
docker run -it python  
</code>
... The docker service running on the host checks to see if we have a copy of the requested image locally. Which, if there isn't, checks the public registry (the docker hub) to see if there's an image named ubuntu available. If it finds it, downloads the image and stores it in its local cache of images (ready for next time) and creates a new container, based on the requested image.

==== link parameter ====
If we're going to connect from one container to another, we need to link them, which tells docker that we explicitly want to allow communication between the two.

When we run a container, we can tell docker that we intend to connect to another container using the link parameter. 
<code>
docker run -it -p 8123:8123 --link db:db -e DATABASE_HOST=DB users-service
</code>
  - docker run -it run a docker image in a container, with an interactive terminal.
  - -p 8123:8123 map the host port 8123 to the container port 8123.
  - link db:db link to the container named db and refer to it as db.
  - -e DATABASE_HOST=db set the DATABASE_HOST environment variable to db.
  - users-service the name of the image to run in our container.
===== Quick commands =====

==== Test your docker installation ====

<code>
$ docker run hello-world
</code>

==== Search for images available on Docker Hub  ====

<code>
$ docker search ubuntu
</code>

==== Download image from Docker Hub ====
<code>
$ docker pull ubuntu
</code>

==== Update image with your changes ====

If you do a change of an image (imagine you install a package using apt) you can update it:

<code>
docker commit -m "What did you do to the image" -a "Author Name" container-id repository/new_image_name
</code>

==== Access to a running image ====
<code>
$ docker exec -it db /bin/bash
</code>

==== See linked containers ====
<code>
docker exec trusting_jang cat /etc/hosts  
</code>

==== Show running containers ====

<code>
docker ps
docker ps -a 
</code>
Last one shows a history.

==== Run a container mounting a folder ====

Realize you need to write the full path:
<code>
docker run -ti -p 8000:8000 -v /home/alfred/Documents/workspaces/newskid/newskid.dockerfile/files:/var/src/newskid/files newskid
</code>
==== Uses of images ====

=== MySQL ===
<code>
docker run --name db -d -e MYSQL_ROOT_PASSWORD=123 -p 3306:3306 mysql:latest  
</code>

This starts a MySQL instance running, allowing access through port 3306 using the root password 123.

docker run tells the engine we want to run an image (the image comes at the end, mysql:latest 

  - --name db names this container db.
  - -d (or --detach) detach - i.e. run the container in the background.
  - -e MYSQL_ROOT_PASSWORD=123 (or --env) environment variables - tells docker we want to provide an environment variable.   - The variable following it is what the MySQL image checks for setting the default root password.
  - -p 3306:3306 (or --publish tells the engine that we want to map the port 3306 from inside the container to out port 3306.


The last part is really important - even though that's the MySQL default port, if we don't tell docker explicitly we want to map it, it will block access through that port (because containers are isolated until you tell them you want access).

=== Php ===

Enable MySQL libraries:
<code>
FROM php:7.0-apache

RUN /usr/local/bin/docker-php-ext-install mysqli
RUN /usr/local/bin/docker-php-ext-install pdo_mysql

RUN apt update && apt install mysql-client-5.5 -y
</code>
===== Dockerfile =====

To build an image from a dockerfile you use ''docker build .'' , or, ''docker build -f /path/to/a/Dockerfile .''. You can also tag your image when building it: ''docker build -t davidsale/dockerizing-python-django-app .'' in this case the tag is called "davidsale/dockerizing-python-django-app".


A basic dockerfile:
<code>
# FROM directive instructing base image to build upon
FROM python:2-onbuild

# COPY startup script into known file location in container
COPY start.sh /start.sh

# EXPOSE port 8000 to allow communication to/from server
EXPOSE 8000

# CMD specifcies the command to execute to start the server running.
CMD ["/start.sh"]
</code>

FROM indicates the image for being use. For example, ''FROM python:2-onbuild'' will use this dockerfile https://github.com/docker-library/python/blob/7663560df7547e69d13b1b548675502f4e0917d1/2.7/onbuild/Dockerfile. Which is extracted from https://hub.docker.com/_/python/.

COPY copies a file or a path inside the container, for example to copy a file: ''COPY start.sh /start.sh'', or to copy the whole folder: ''COPY . /usr/src/app''

To link your 8000 port with the 8000 port inside the container you use ''EXPOSE''.

  * ''CMD["command"]'' executes the main command, when it finishes the container will stop. 
  * ''RUN command'' runs a console command.


===== Docker Compose =====

  * https://docs.docker.com/compose/

Docker Compose lets you create a file which defines each container in your system, the relationships between them, and build or run them all.

You need to have a new file in the root of your project called ''docker-compose.yml''. It's more or less like these:
<code>
version: '2'  
services:  
  users-service:
    build: ./users-service
    ports:
     - "8123:8123"
    depends_on:
     - db
    environment:
     - DATABASE_HOST=db
  db:
    build: ./test-database
</code>
<code>
version: '2'
services:
  web:
    build: .
    ports:
    - "5000:5000"
    volumes:
    - .:/code
    - logvolume01:/var/log
    links:
    - redis
  redis:
    image: redis
volumes:
  logvolume01: {}
</code>

The next commands will buld all of the images, create containers and run them in the correct order.
<code>
docker-compose build  
docker-compose up 
</code>

The ''build'' value for each of our services in the docker-compose.yml tells docker where to go to find the Dockerfile. When we run docker-compose up, docker starts all of our services. Notice from the Dockerfile we can specify ports and dependencies. 

Whe we run ''docker compose down'' we are shutting down the containers.

==== Volumes ====
<code>
docker volume ls
docker volume prune
</code>
==== With networks ====
<code>
version: "3"
services:

  proxy:
    build: ./proxy
    networks:
      - frontend
  app:
    build: ./app
    networks:
      - frontend
      - backend
  db:
    image: postgres
    networks:
      - backend

networks:
  frontend:
    # Use a custom driver
    driver: custom-driver-1
  backend:
    # Use a custom driver which takes special options
    driver: custom-driver-2
    driver_opts:
      foo: "1"
      bar: "2"
</code>
===== Docker networks =====
List docker networks:
<code>
$ sudo docker network ls
</code>
Create network:
<code>
sudo docker network create mynetwork
</code>
Now you can inspect its details (you can see the assigned ip addresses to the hosts):
<code>
$ docker network inspect mynetwork
</code>
To add a docker container to a network just add the parameter:
<code>
--network mynetwork
</code>

==== Assign ip's ====

First you need to create you own docker network:
<code>
docker network create --subnet=172.18.0.0/16 mynet123
</code>
Then run with ip:
<code>
docker run --net mynet123 --ip 172.18.0.22 -it ubuntu bash
</code>
Additionally:
<code>
--hostname to specify a hostname
--add-host to add more entries to /etc/hosts
</code>
===== Use cases =====
==== Using external code ====
=== Git Clone ===
This requires installing an SSH key for private repositories.

While this technique may work for managed cloud servers, it isn't recommended for container-based deployments for a few reasons:

  - Including SSH keys within container images poses a security risk, as images are often hosted publicly, or privately using a third-party Docker Registry
  - Containers are designed to be ephemeral, with new versions of code built into a new container image, rather than updating the code of an existing container using Git
  - Containers should be as small as possible, avoiding the installation of any unnecessary tools

=== With sharing volumes ===

use the -v switch to specify the local directory path that you wish to mount, along with the location where it should be mounted within the running container:
<code>
docker run -d -P --name <name of your container> -v /path/to/local/directory:/path/to/container/directory <image name> ... 
</code>

Using this command, the host's directory becomes accessible to the container under the path you specify. This is particularly useful when developing locally, as you can use your favorite editor to work locally, commit code to Git, and pull the latest code from remote branches.

=== With ADD or COPY commands ===
You can use the COPY command within a Dockerfile to copy files from the local filesystem into a specific directory within the container. The following Dockerfile example would recursively add the current working directory into the /app directory of the container image:
<code>
# Dockerfile for a Ruby 2.2 container

FROM ruby:2.2

RUN mkdir /app  
COPY . /app  
</code>
The ADD command is similar to the COPY command, but has the added advantage of fetching remote URLs and extracting tarballs.

==== Step by step case ====
=== 1. Create dockerfile ===
<code>
FROM ubuntu:12.04

RUN apt-get update
RUN apt-get install -y nginx

EXPOSE 80 443

CMD ["nginx", "-g", "daemon off;"]
</code>

=== 2. Build and launch it ===
<code>
$ docker build . -t estars_nginx
</code>


If you are writing the dockfile probably you will prefer to do something like:
<code>
$ docker build . -t estars_nginx --no-cache
</code>

=== 3. Launch it ===
<code>
$ docker run -d -p 8000:80 estars_nginx
$ docker run -ti -p 8000:80 estars_nginx
</code>

=== 4. Stop it ===
<code>
$ docker stop estars_nginx
</code>
===== Problems =====

==== Could not read CA certificate ====

You will need to regenerate certificates for the default machine:

<code>
docker-machine regenerate-certs default
docker-machine restart default
</code>

==== Delete untagged images ====
<code>
docker rmi -f $(docker images | grep "^<none>" | awk '{print $3}')
</code>

==== Clean docker folder ====
Use this script in ''/var/lib/docker'':
<code>
#!/bin/sh
set -e

dir="$1"

if [ -z "$dir" ]; then
	{
		echo 'This script is for destroying old /var/lib/docker directories more safely than'
		echo '  "rm -rf", which can cause data loss or other serious issues.'
		echo
		echo "usage: $0 directory"
		echo "   ie: $0 /var/lib/docker"
	} >&2
	exit 1
fi

if [ "$(id -u)" != 0 ]; then
	echo >&2 "error: $0 must be run as root"
	exit 1
fi

if [ ! -d "$dir" ]; then
	echo >&2 "error: $dir is not a directory"
	exit 1
fi

dir="$(readlink -f "$dir")"

echo
echo "Nuking $dir ..."
echo '  (if this is wrong, press Ctrl+C NOW!)'
echo

( set -x; sleep 10 )
echo

dir_in_dir() {
	inner="$1"
	outer="$2"
	[ "${inner#$outer}" != "$inner" ]
}

# let's start by unmounting any submounts in $dir
#   (like -v /home:... for example - DON'T DELETE MY HOME DIRECTORY BRU!)
for mount in $(awk '{ print $5 }' /proc/self/mountinfo); do
	mount="$(readlink -f "$mount" || true)"
	if dir_in_dir "$mount" "$dir"; then
		( set -x; umount -f "$mount" )
	fi
done

# now, let's go destroy individual btrfs subvolumes, if any exist
if command -v btrfs > /dev/null 2>&1; then
	root="$(df "$dir" | awk 'NR>1 { print $NF }')"
	root="${root#/}" # if root is "/", we want it to become ""
	for subvol in $(btrfs subvolume list -o "$root/" 2>/dev/null | awk -F' path ' '{ print $2 }' | sort -r); do
		subvolDir="$root/$subvol"
		if dir_in_dir "$subvolDir" "$dir"; then
			( set -x; btrfs subvolume delete "$subvolDir" )
		fi
	done
fi

# finally, DESTROY ALL THINGS
( set -x; rm -rf "$dir" )
</code>

===== Configure installation =====

==== Using Docker as not root user ====
From the documentation:

> The docker daemon binds to a Unix socket instead of a TCP port. By default that Unix socket is owned by the user root and other users can only access it using sudo. The docker daemon always runs as the root user. If you don’t want to use sudo when you use the docker command, create a Unix group called docker and add users to it. When the docker daemon starts, it makes the ownership of the Unix socket read/writable by the docker group.

The steps would be:
<code>
$ sudo groupadd docker
$ sudo usermod -aG docker $USER
</code>

If it did not work:
<code>
sudo groupadd docker
sudo usermod -aG docker $USER
newgrp docker
docker run hello-world
</code>
==== The Docker service configuration ====
You can control the docker service with: ''service docker start|stop|restart|status''. 

You also can start it manually with the ''dockerd'' command as sudo user.

For configuring it, in ''/etc/docker/'' folder there should be a ''daemon.json'' file. This is the config documentation for that: https://docs.docker.com/engine/reference/commandline/dockerd/#miscellaneous-options
===== Other useful links =====

  * https://docs.docker.com/machine/examples/aws/
  * [[http://www.dwmkerr.com/learn-docker-by-building-a-microservice/|A really good tutorial]]
  * https://github.com/odewahn/docker-jumpstart
  * https://github.com/veggiemonk/awesome-docker
  * https://codefresh.io/blog/everyday-hacks-docker/

===== Tips =====

Install MySQL on setting the password:
<code>
FROM php:7.0-apache

RUN { \
		echo mysql-server mysql-server/root_password password mypassword; \
		echo mysql-server mysql-server/root_password_again password mypassword; \
	} | debconf-set-selections

RUN apt update && apt install -y mysql-server
</code>
Programming

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