Fedora 32
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Podman : Use Dockerfile
2020/05/11
 
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 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>
--> 26ed0688ebf
STEP 3: RUN dnf -y install nginx
.....
.....
STEP 6: CMD ["/usr/sbin/nginx", "-g", "daemon off;"]
STEP 7: COMMIT srv.world/nginx_server:latest
--> f0bde03754e
f0bde03754eb78b94d465246c9c239cc9d403a92e990cac1533b09fdecbe3846

[root@dlp ~]#
podman images

REPOSITORY                          TAG      IMAGE ID       CREATED          SIZE
srv.world/nginx_server              latest   f0bde03754eb   16 seconds ago   406 MB
srv.world/fedora_httpd              latest   a461b4b0b704   4 minutes ago    452 MB
registry.fedoraproject.org/fedora   latest   d81c91deec0d   11 days ago      208 MB

# run container

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

10fda09cd1e4a660f8457d95e95d877597c7638fc5081073caaf56839c4950b8

[root@dlp ~]#
podman ps

CONTAINER ID  IMAGE                          COMMAND               CREATED        STATUS            PORTS               NAMES
10fda09cd1e4  srv.world/nginx_server:latest  /usr/sbin/nginx -...  8 seconds ago  Up 8 seconds ago  0.0.0.0:80->80/tcp  tender_bouman

# 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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