Dockerfile

April 15, 2020

Page content

Terminology

context: A build’s context is the set of files located in the specified PATH or URL¹.

Dockerfile sample

FROM ubuntu:20.04
ENV TZ=America/Los_Angeles

RUN mkdir -p /home/my_user
COPY ./files/in_home /home/my_user/in_home

ARG DEBIAN_FRONTEND=noninteractive
RUN apt update && apt upgrade -y
RUN apt install -y nginx php

COPY ./files/nginx/my.conf /etc/nginx/sites-available/my.conf
RUN ln -s /etc/nginx/sites-available/my.conf /etc/nginx/sites-enabled/my.conf

CMD ["nginx", "-g", "daemon off;"]

Here is the context.

.
├── Dockerfile
└── files
    ├── in_home(dir)
    └── nginx
        └── my.conf

Exec the commands below and run

docker build -t atlex/test:v1 ./
docker run --name="DockerfileTest" -d -p 50001:80 atlex/test:v1

Details about the sample

FROM ubuntu:20.04: Build the docker image from Ubuntu 20.04 image.
ENV TZ=America/Los_Angeles: Set environment variable TimeZone as America/Los_Angeles.
RUN mkdir -p /home/my_user: Run command mkdir -p /home/my_user.
COPY ./files/in_home /home/my_user/in_home: Copy local Directory ./files/in_home to the container (image) as name /home/my_user/in_home.
ARG DEBIAN_FRONTEND=noninteractive: Well known problem in Ubuntu docker image².

Tip: ADD or COPY

https://nickjanetakis.com/blog/docker-tip-2-the-difference-between-copy-and-add-in-a-dockerile

First, you can use a URL instead of a local file / directory. Secondly, you can extract a tar file from the source directly into the destination. … If you’re copying in local files to your Docker image, always use COPY because it’s more explicit.

https://serverfault.com/questions/949991/how-to-install-tzdata-on-a-ubuntu-docker-image

Memo

WORKDIR: kind of cd