CentOS 8
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Podman : Use Dockerfile2019/10/11

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

FROM centos
MAINTAINER ServerWorld <admin@srv.world>

RUN dnf -y install nginx
RUN echo "Dockerfile Test on Nginx" > /usr/share/nginx/html/index.html

CMD ["/usr/sbin/nginx", "-g", "daemon off;"]

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

[root@dlp ~]#
podman build -t srv.world/nginx_server:latest .

STEP 1: FROM centos
STEP 2: MAINTAINER ServerWorld <admin@srv.world>
--> 47a4ec064edb6846d07d909d9573bd935123bedbfec1fac891f7d334dce2abda
STEP 3: FROM 47a4ec064edb6846d07d909d9573bd935123bedbfec1fac891f7d334dce2abda
STEP 9: FROM f3afe7e61abc2366eff3da48755f775bdfa6e68180ce8525af391d4d99a200b7
STEP 10: CMD ["/usr/sbin/nginx", "-g", "daemon off;"]
--> 41c48e1d242161269177ee5668af907ea7a6534a341b5eb489d62eaf767b7612
STEP 11: COMMIT srv.world/nginx_server:latest

[root@dlp ~]#
podman images

REPOSITORY                 TAG      IMAGE ID       CREATED          SIZE
srv.world/nginx_server     latest   41c48e1d2421   18 seconds ago   308 MB
srv.world/centos_httpd     latest   67edc4066f76   6 hours ago      368 MB
docker.io/library/centos   latest   0f3e07c0138f   8 days ago       227 MB

# run container

[root@dlp ~]#
podman run -d -p 80:80 srv.world/nginx_server


[root@dlp ~]#
podman ps

CONTAINER ID  IMAGE                          COMMAND               CREATED         STATUS             PORTS               NAMES
dd30cc06855f  srv.world/nginx_server:latest  /usr/sbin/nginx -...  17 seconds ago  Up 16 seconds ago>80/tcp  nostalgic_lamarr

# verify accesses

[root@dlp ~]#
curl localhost

Dockerfile Test on Nginx
# also possible to access via container network

[root@dlp ~]#
podman inspect -l | grep \"IPAddress

            "IPAddress": "",
[root@dlp ~]#

Dockerfile Test on Nginx
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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