Docker : Use Dockerfile2023/04/27

	Use Dockerfile and create Docker images automatically. It is also useful for configuration management.
[1]	For example, Create a Dockerfile that Apache2 is installed and started.

root@dlp:~#

vi Dockerfile

# create new

FROM ubuntu
MAINTAINER ServerWorld <admin@srv.world>

RUN apt-get update
RUN apt-get -y install tzdata
RUN apt-get -y install apache2
RUN echo "Dockerfile Test on Apache2" > /var/www/html/index.html

EXPOSE 80
CMD ["/usr/sbin/apachectl", "-D", "FOREGROUND"]

# build image ⇒ docker build -t [image name]:[tag] .

root@dlp:~#

docker build -t srv.world/ubuntu-apache2:latest ./

Sending build context to Docker daemon  20.99kB
Step 1/8 : FROM ubuntu
 ---> 08d22c0ceb15
Step 2/8 : MAINTAINER ServerWorld <admin@srv.world>
 ---> Running in 0a226c7e4895
Removing intermediate container 0a226c7e4895
 ---> 943e43d6e7a4

.....
.....

Successfully built 886e2f7307a1
Successfully tagged srv.world/ubuntu-apache2:latest

root@dlp:~#

docker images

REPOSITORY                 TAG       IMAGE ID       CREATED         SIZE
srv.world/ubuntu-apache2   latest    886e2f7307a1   3 minutes ago   235MB
srv.world/ubuntu-nginx     latest    df0287c5017d   7 minutes ago   177MB
ubuntu                     latest    08d22c0ceb15   7 weeks ago     77.8MB

# run container

root@dlp:~#

docker run -d -p 8081:80 srv.world/ubuntu-apache2

7e5fbd168ce3ed1e5af58de4e9597b3f553cfb7d58568c02a1c32cc123dc6f26

root@dlp:~#

docker ps

CONTAINER ID   IMAGE                      COMMAND                  CREATED          STATUS         PORTS                                   NAMES
7e5fbd168ce3   srv.world/ubuntu-apache2   "/usr/sbin/apachectl…"   10 seconds ago   Up 8 seconds   0.0.0.0:8081->80/tcp, :::8081->80/tcp   determined_keller

# verify accesses

root@dlp:~#

curl localhost:8081

Dockerfile Test on Apache2

The format of Dockerfile is [INSTRUCTION arguments] .
Refer to the following description for INSTRUCTION.

INSTRUCTION	Description
FROM	iIt sets the Base Image for subsequent instructions.
MAINTAINER	It sets the Author field of the generated images.
RUN	It will execute any commands when Docker image will be created.
CMD	It will execute any commands when Docker container will be executed.
ENTRYPOINT	It will execute any commands when Docker container will be executed.
LABEL	It adds metadata to an image.
EXPOSE	It informs Docker that the container will listen on the specified network ports at runtime.
ENV	It sets the environment variable.
ADD	It copies new files, directories or remote file URLs.
COPY	It copies new files or directories. The differences of [ADD] are that it's impossible to specify remore URL and also it will not extract archive files automatically.
VOLUME	It creates a mount point with the specified name and marks it as holding externally mounted volumes from native host or other containers
USER	It sets the user name or UID.
WORKDIR	It sets the working directory.

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