Ubuntu 23.04
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Docker : Use Dockerfile
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.
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

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

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

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

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

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

docker ps

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

# verify accesses

curl localhost:8081

Dockerfile Test on Apache2
The format of Dockerfile is [INSTRUCTION arguments] .
Refer to the following description for INSTRUCTION.
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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