Docker : Use Dockerfile2024/06/13

	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:~#

apt -y install docker-buildx

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 ./

[+] Building 5.3s (4/8)                                          docker:default
 => [internal] load build definition from Dockerfile                       0.1s
 => => transferring dockerfile: 297B                                       0.0s
 => [internal] load .dockerignore                                          0.1s
 => => transferring context: 2B                                            0.0s
 => [internal] load metadata for docker.io/library/ubuntu:latest           0.0s
 => [1/5] FROM docker.io/library/ubuntu                                    0.0s
 => [2/5] RUN apt-get update                                               5.2s

.....
.....

[+] Building 29.6s (9/9) FINISHED                                docker:default
 => [internal] load build definition from Dockerfile                       0.1s
 => => transferring dockerfile: 297B                                       0.0s
 => [internal] load .dockerignore                                          0.1s
 => => transferring context: 2B                                            0.0s
 => [internal] load metadata for docker.io/library/ubuntu:latest           0.0s
 => [1/5] FROM docker.io/library/ubuntu                                    0.0s
 => [2/5] RUN apt-get update                                               7.7s
 => [3/5] RUN apt-get -y install tzdata                                    4.7s
 => [4/5] RUN apt-get -y install apache2                                  16.3s
 => [5/5] RUN echo "Dockerfile Test on Apache2" > /var/www/html/index.htm  0.3s
 => exporting to image                                                     0.4s
 => => exporting layers                                                    0.4s
 => => writing image sha256:d987da01ec6c2950e15b8ba662834d235bdcab141c181  0.0s
 => => naming to srv.world/ubuntu-apache2:latest                           0.0s

root@dlp:~#

docker images

REPOSITORY                 TAG       IMAGE ID       CREATED              SIZE
srv.world/ubuntu-apache2   latest    d987da01ec6c   About a minute ago   225MB
srv.world/ubuntu-nginx     latest    f3f6605bb20c   15 minutes ago       123MB
ubuntu                     latest    17c0145030df   13 days ago          76.2MB

# run container

root@dlp:~#

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

88c8b459e9ff03d466924c8bb03f23ac5ea27b7b638a7ba4193b2c7e281b9787

root@dlp:~#

docker ps

CONTAINER ID   IMAGE                      COMMAND                  CREATED          STATUS          PORTS                                   NAMES
88c8b459e9ff   srv.world/ubuntu-apache2   "/usr/sbin/apachectl…"   14 seconds ago   Up 13 seconds   0.0.0.0:8081->80/tcp, :::8081->80/tcp   naughty_khayyam

# 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	It 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 remote 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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