Dockerfile

Dockerfile

Dockerfile is a blueprint of docker image.

To build this, we can create new docker image.

Steps

• Prepare Dockerfile
• Build dockerfile

To build dockerfile, run following

docker build .

. is current directly and docker context

Layer

One line has one Layer.

But too much

Especially, we need to install a lot of packages to prepare environments we want to use.

In this case, we can use && commands to combine commands

Example

FROM ubuntu:latest
RUN apt-get update && apt-get install nginx \
apt-get install curl \
apt-get install essential-build

Dockerfile description

Description	Explanation	Example
FROM	Original docker image	FROM ubuntu:latest
USER	Use this user	USER vault
ARG	Add arguments	ARG key=”value”
ENTRYPOINT	Execute command(cannot override)	ENTRYPOINT [“java”, “-jar”, “/app.jar”]
RUN	Execute command(can override)	RUN touch test
CMD	Run command(not create layer) Describe at the bottom of Dockerfile CMD [“executable”, “param1”, “param2”]	CMD [“ls”]
COPY	Copy folder, file COPY <src> <dst>	COPY test.txt /newdir/
ADD	Copy file (tar etc…)	ADD compress.tar /