Fedora 33
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Podman : Use Dockerfile
2020/11/06
 
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 fedora
MAINTAINER ServerWorld <admin@srv.world>

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

EXPOSE 80
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 fedora
STEP 2: MAINTAINER ServerWorld <admin@srv.world>
--> 0970f1d046f
STEP 3: RUN dnf -y install nginx
.....
.....
STEP 6: CMD ["/usr/sbin/nginx", "-g", "daemon off;"]
STEP 7: COMMIT srv.world/nginx-server:latest
--> 5c98ec35fda
5c98ec35fda656ff9245c41b89a95895a2b8649285399cce4ce0b29400d8f71f

[root@dlp ~]#
podman images

REPOSITORY                         TAG     IMAGE ID      CREATED         SIZE
srv.world/nginx-server             latest  5c98ec35fda6  39 seconds ago  419 MB
srv.world/fedora-httpd             latest  56430ecb044d  6 minutes ago   439 MB
registry.fedoraproject.org/fedora  latest  79fd58dc7611  8 days ago      181 MB

# run container

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

8bbbebb255d6786081e666e5cc0318d3f9f28e1a78fb051ff05df747af2bb7d8

[root@dlp ~]#
podman ps

CONTAINER ID  IMAGE                          COMMAND               CREATED         STATUS             PORTS               NAMES
8bbbebb255d6  srv.world/nginx-server:latest  /usr/sbin/nginx -...  11 seconds ago  Up 11 seconds ago  0.0.0.0:80->80/tcp  dreamy_roentgen

# 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": "10.88.0.8",
[root@dlp ~]#
curl 10.88.0.8

Dockerfile Test on Nginx
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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