CentOS 7
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Docker : Use Dockerfile2015/06/27

Use Dockerfile and create Docker images automatically.
It is also useful for configuration management.
[1] For example, Create a Dockerfile that Apache httpd is installed and started.
[root@dlp ~]#
vi Dockerfile
# create new

FROM centos
MAINTAINER ServerWorld <admin@srv.world>

RUN yum -y install httpd
RUN echo "Dockerfile Test on Aapche httpd" > /var/www/html/index.html

ENTRYPOINT ["/usr/sbin/httpd"]

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

[root@dlp ~]#
docker build -t srv.world/centos-httpd:latest ./

Sending build context to Docker daemon  11.78kB
Step 1/7 : FROM centos
 ---> 300e315adb2f
Step 2/7 : MAINTAINER ServerWorld <admin@srv.world>
 ---> Running in 6e83e9b69134
Removing intermediate container 6e83e9b69134
 ---> 3b1af99319a3
Step 3/7 : RUN yum -y install httpd
 ---> Running in 3680093e103f

Successfully built 7cf442f4e930
Successfully tagged srv.world/centos-httpd:latest

[root@dlp ~]#
docker images

REPOSITORY               TAG       IMAGE ID       CREATED          SIZE
srv.world/centos-httpd   latest    7cf442f4e930   39 seconds ago   250MB
srv.world/centos-nginx   latest    6adb1438d24f   4 minutes ago    289MB
centos                   latest    300e315adb2f   5 months ago     209MB

# run container

[root@dlp ~]#
docker run -d -p 8081:80 srv.world/centos-httpd

[root@dlp ~]#
docker ps

CONTAINER ID   IMAGE                    COMMAND                  CREATED         STATUS         PORTS                                   NAMES
fbbe54203409   srv.world/centos-httpd   "/usr/sbin/httpd -D …"   7 seconds ago   Up 6 seconds>80/tcp, :::8081->80/tcp   compassionate_taussig

# verify accesses

[root@dlp ~]#
curl localhost:8081

Dockerfile Test on Aapche httpd
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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