Learning - Dockerfile

This is to refresh my Dockerfile knowledge.

alphine

Create Dockerfile

FROM alphine:3.4
MAINTAINER Mark Takacs mark@takacsmark.com

RUN ark update
RUN ark add vim
RUN apk add curl

Build

docker build -t taka/alpine-smarter:1.0 .

Intermediate images

The Docker intermediate images can speed up the rebuilding process.

docker images -a

To reduce number of intermediate images, update Dockerfile as below

FROM alphine:3.4
MAINTAINER Mark Takacs mark@takacsmark.com

RUN ark update && \
       ark add vim && \
       apk add curl

Clean up dangling image

docker images --filter "dangling=true"
docker rmi $(docker images -q --filter "dangling=true")

python

Dockerfile

• For normal python

FROM python:3.6.1

RUN pip install numpy

• For alpine version takes much longer time to build

FROM python:3.6.1-alpine

RUN apk update && apk add build-base
RUN ln -s /usr/include/locale.h /usr/include/xlocale.h

RUN pip install numpy scipy

conda3

• miniconda3

docker run --rm -ti continuumio/miniconda3 /bin/bash
conda list
conda install numpy

• anaconda3

docker run --rm -ti continuumio/anaconda3 /bin/bash
conda list

phpslim

Dockerfile

Choose php:7.1.2-apache

Got to https://getcomposer.org, and run installation commands in container

FROM php:7.1.2-apache

RUN ....

COPY ./composer.json /var/www/html/

RUN apt-get update & apt-get install -y git

RUN composer install

Map directory

To run docker container with option -v /var/www/html/vendor to indicate using image /var/www/html/vendor folder.

docker run --rm -v $(pwd):/var/www/html/ -v /var/www/html/vendor -p 80:80 takacsmark/phpslim-tut:1.0

As the result, the /var/www/html is mapped to local directory, but /var/www/html/vendor is image directory.

Change DocumentRoot

Add following line into Dockerfile to change the DocumentRoot to /var/www/html/public

RUN set -i 's/DocumentRoot.*$/DocumentRoot \/var\/www\/html\/public/' /etc/apache2/sites-enabled/000-default.conf

Enable default hello message

Create a file /var/www/html/public/.htaccess

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^ index.php [QSA,L]

Run following command in container to enable module rewrite

a2enmod rewrite

Then add following line in Dockerfile

RUN a2enmod rewrite

Options

COPY

COPY ./config.txt /usr/src/config.txt

ADD

• Add URL file from internet

• Add tar file

• Add compressed file

RUN

EXPOSE

Port

USER

WORKDIR

ARG

LABEL

ENTRYPOINT & CMD

To run command echo Welcome after container created, following configuration can be used.

CMD "Welcome"
ENTRYPOINT echo

The CMD option can be replace using docker run command line, ENTRYPOINT can't. For example, following command will run echo Hello.

docker run echo_image 'Hello'

ENV

References

Dockerfile Tutorial by Example - ( Part I - Basics )
Dockerfile Tutorial by Example - ( Part II - Best practices )
Dockerfile Tutorial by Example - ( Part III - Creating a docker PHP Slim image )