Docker Notes

docker_guide

Docker:
"Docker is an open platform for building, shipping and running distributed applications. 
It gives programmers, development teams and operations engineers the common 
toolbox they need to take advantage of the distributed and networked nature of modern applications."

In other words , Docker is an abstraction on top of low-level operating system tools that 
allows you to run one or more containerized processes or applications within one or more virtualized Linux instances.


Docker images:
The Docker Flow, the fundamental concept, in Docker, it all begins with an image. 
An image is every file that makes up just enough of the operating system to do what you need to do. 
Traditionally you'd install a whole operating system with everything for each application you do. 
With Docker you pair it way down so that you have a little container with just enough of the operating system to 
do what you need to do, and you can have lots and lots of these efficiently on a computer.

List All Docker Images:
command:    docker images

List running images:
docker ps -a 

to get last images runned :

docker ps -l



docker run takes an images and run into a container 

example: docker run ubuntu:latest bash

check which distribution using: 
command:  cat /etc/lsb-release

to exit from running docker:

exit 

flow till now:

docker image ---> docker run ---> running container  ---> stopped container --- > docker commit ---> new image 

Commit command:

docker commit 8c92861cf5e4  ( 8c92861cf5e4 i.e. container id)

above will generate a image id like this:
sha256:3bc95772fe9b49b137ebfdf9afda990afbaf245e03132ab592b6d632d6b7a002

we use docker tag command to give images (e.g.3bc95772fe9b49b137ebfdf9afda990afbaf245e03132ab592b6d632d6b7a002 ) a name
docker tag 3bc95772fe9b49b137ebfdf9afda990afbaf245e03132ab592b6d632d6b7a002 my-image

now if you run docker images you can see new image names my-image 

and now you can run that image like:

docker run -ti my-image bash

now best way to do is do it direct:

e.g.

docker commit happy_poltras my-image-2

note: happy_poltras is the container name , and my-image-2 is the tag / new image name 

to run any command inside container as soon as container started

docker run -ti ubuntu bash -c "sleep 3 , echo all done"

---------------------------------------------------------------------------------------
attaching and detaching contained i.e. running docker in background 
---------------------------------------------------------------------------------------

docker run -d -ti ubuntu bash

you will see something like below:
7b1621cac8e64c04ea46fab6ee791b3729b21ed7d61c7a2123d0e1524f93610a

now when you want login in running container , use below command:

docker ps -l

it will list the last contaner runned  and it will have a name (e.g. boring_mclean)

use that name to login in that container:

docker attach boring_mclean

now if you want to detach again without stoping it:
type controll +p , controll + Q

other way to use detached continer is 

docker exec -ti boring_mclean bash


To check the container logs run below command:
docker logs boring_mclean

to remove old container

docker rm boring_mclean

--------------------
enable ports:
--------------------

docker run -ti -p 45678:45678 -p 45679:45679 --name any-server ubuntu:14.04


to know the docker ip  , run below command: 
docker-machine ip

to see which ports are actually running 

docker port  any-server


to enable UDP port:

docker run -p 1234:1234/udp -ti ubuntu bash


linking two docker container:

first container:  docker run -ti -name server ubuntu:14.04 bash

second container: docker run -ti --link server --name client ubuntu:14.04 bash
 
 Dynamic Docker linking  using docker Private network:

docker network create example 

First docker: docker run -ti --net=example --name server ubuntu:14.04 bash

second container: docker run -ti --link server --net=example --name client ubuntu:14.04 bash

to only let docker work in localhost , use command below:
docker run -ti -p127.0.0.1:1234;1234/tcp ubuntu:14.04 bash

removing image from system:

docker rmi image-name:tag


To login into docker host in ssh mode run:

docker-machine ssh

Run docker with shared folder in docker host machine:

mkdir example 

current directory: /home/docker

docker run -ti -v /home/docker/example:/shared-folder ubuntu bash

now if we can share that shared folder with another docker container:

docker run -ti -v /shared-data ubuntu bash

we can work and store file in directly shared-data folder 

now we we run older image again we can work on same volume:

docker run -ti --volumes-from #cntainer_name ubuntu:bash

search image in docker:

docker search ubuntu


--------------------------------------------

Building images with docker file 
--------------------------------------------

Tobuild a docker image from a docker file in current directory , use below code

docker build -t result_name .  (here . means current directory )


sample docker file 

File name: Dockerfile
file contents:

FROM debain:sid

RUN apt-get -y update 

RUN apt-get install nano 

CMD "nano" "/tmp/notes"


or for example
==========================================
Product level example for running node.js application
==========================================

# using debian:jessie for it's smaller size over ubuntu
FROM debian:jessie

# Replace shell with bash so we can source files
RUN rm /bin/sh && ln -s /bin/bash /bin/sh

# Set environment variables
ENV appDir /var/www/app/current

# Run updates and install deps
RUN apt-get update

RUN apt-get install -y -q --no-install-recommends \
apt-transport-https \
build-essential \
ca-certificates \
curl \
g++ \
gcc \
git \
make \
nginx \
sudo \
wget \
&& rm -rf /var/lib/apt/lists/* \
&& apt-get -y autoclean

ENV NVM_DIR /usr/local/nvm
ENV NODE_VERSION 5.1.0

# Install nvm with node and npm
RUN curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.29.0/install.sh | bash \
&& source $NVM_DIR/nvm.sh \
&& nvm install $NODE_VERSION \
&& nvm alias default $NODE_VERSION \
&& nvm use default

# Set up our PATH correctly so we don't have to long-reference npm, node, &c.
ENV NODE_PATH $NVM_DIR/versions/node/v$NODE_VERSION/lib/node_modules
ENV PATH $NVM_DIR/versions/node/v$NODE_VERSION/bin:$PATH

# Set the work directory
RUN mkdir -p /var/www/app/current
WORKDIR ${appDir}

# Add our package.json and install *before* adding our application files
ADD package.json ./
RUN npm i --production

# Install forever so we can run our application
RUN npm i -g forever

# Add application files
ADD . /var/www/app/current

#Expose the port
EXPOSE 4500

CMD ["forever", "start", "./bin/www"]



///////////////////////////////////////
Refs:

https://blog.giantswarm.io/getting-started-with-docker-and-meanjs/
https://blog.codeship.com/running-mean-web-application-docker-containers-aws/
To run application properly , we have to run mongodb in diffderent container and connect two docker container by server name, like below:
first:  docker run -p 27017:27017 -d --name db mongo
then: docker run -ti -p 3000:3000 --link db:db_1 kjbinu/bigbox bash
 
 
 ------------------------------------------------------------------
 
 How to make password protected container / image 
 
 Dockerfile
=============

FROM ubuntu:14.04
MAINTAINER Sandip Das <sandip.sandip.das5@gmail.com>

RUN apt-get update && apt-get install -y openssh-server
RUN mkdir /var/run/sshd
RUN echo 'root:W1LZSpK0Dtkb2SmJ' | chpasswd
RUN sed -i 's/PermitRootLogin without-password/PermitRootLogin yes/' /etc/ssh/sshd_config

# SSH login fix. Otherwise user is kicked off after login
RUN sed 's@session\s*required\s*pam_loginuid.so@session optional pam_loginuid.so@g' -i /etc/pam.d/sshd

ENV NOTVISIBLE "in users profile"
RUN echo "export VISIBLE=now" >> /etc/profile

EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]



docker build -t bigbox .

docker run -d -P --name bigbox_app bigbox

docker port bigbox_app 22

--->0.0.0.0:32768

ssh root@0.0.0.0 -p 32768

-------> enter password
W1LZSpK0Dtkb2SmJ
 
to run the final app:
docker run -p 27017:27017 -d --name db mongo
docker run -d -p 3000:3000 -P --name bigbox_app webmagician/bigbox
docker port bigbox_app 22


--->0.0.0.0:32768

ssh root@0.0.0.0 -p 32768
-------> enter password
W1LZSpK0Dtkb2SmJ