Post

Docker - create dockerfiles images

Posted Updated
By Grace L
4 min read

create dockerfiles images

basic

hello world

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FROM scratch
COPY hello /
CMD ["/hello"]

build 1

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~ $ wget --content-disposition 'https://github.com/linuxacademy/content-Introduction-to-Containers-and-Docker/raw/master/lessonfiles/demo-app.tar'

~ $ tar -xf demo-app.tar
~ $ ls
app  code   default.conf  demo-app.tar
Desktop    Downloads   Music	 Public  Templates  Videos
bin  code2  default.conf   demos		Documents  index.html  Pictures  sample  venvs

~ $ cd app

app $ ls
index.js  node_modules	nodesource_setup.sh
package.json  package-lock.json  public  views


app $ vim Dockerfile

docker build . -t appimage

docker run -dt --name app01 appimage

docker inspect app01 | grep IPAddress

curl 172.17.0.2:8080

Dockerfile

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# define parent image with FROM;
# all valid Dockerfiles must begin with FROM.
FROM node:10-alpine

# create a directory and set its owner.
# use the RUN command, execute any commands against the shell.
# Our image is based on Alpine, which uses the ash shell
RUN mkdir -p /home/server/app/node_modules && chown -R server:server /home/server/app

# move into the /home/node/app directory.
# We do this by setting a working directory with WORKDIR.
# Any RUN, CMD, COPY, ADD, and ENTRYPOINT instructions that follow will be performed in this directory:
WORKDIR /home/server/app

# to add our files.
# two options for this: COPY or ADD.
# ADD can pull files from outside URLs, and thus utilizes additional functionality.
# COPY: package* files are all local
# With the first argument being our source file(s) and the second our destination.
COPY package*.json ./

# ensure the prerequisite packages for our application are installed from NPM.
# These are just more RUN commands.
RUN npm config set registry https://registry.npmjs.org/
RUN npm install


# We can now copy over the rest of our application files using COPY.
# We'll also want to set the owner of our working directory to the node user and group.
# Since we're on Linux, this can also be achieved using some special COPY functionality.
COPY --chown=server:server . .

# to switch users.
# This works similarly to the previous WORKDIR command, but now we're switching users not directories for any following RUN, CMD, and ENTRYPOINT commands.
USER server

# Our application is hosted on port 8080, so we also want to make sure that port is available on our container.
# For this, we'll use the EXPOSE keyword.
EXPOSE 8080

# And now, finally, we want to provide the command (CMD) run as soon as the container is launched.
# Unlike RUN, CMD's preferred format doesn't take this as a shell command.
# Instead, the executable name should be supplied in an array, followed by any parameters:
# CMD ["executable","param1","param2"].
CMD [ "node", "index.js" ]

Image Management

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docker pull image_name
docker image ls
docker image rm image_name

docker image prune -a   # remove useless image

docker image inspect

build 2

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cloud_user@dockerhost:~$ ls
containerhub

cloud_user@dockerhost:~$ cd containerhub/

cloud_user@dockerhost:~/containerhub$ ls
files
cloud_user@dockerhost:~/containerhub$ ls files/
default.conf  html
cloud_user@dockerhost:~/containerhub$ cat files/default.conf
server {
        listen 80 default_server;
        listen [::]:80 default_server;

        root /var/www/html/;
}


cloud_user@dockerhost:~/containerhub$ vim Dockerfile

cloud_user@dockerhost:~/containerhub$ docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS      PORTS               NAMES
cloud_user@dockerhost:~/containerhub$ docker image ls
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE

cloud_user@dockerhost:~/containerhub$ docker build . -t web

cloud_user@dockerhost:~/containerhub$ docker run -dt -p 80:80 --name web01 web
f0cd9a64eee810886db2229f233191eb2ef11de1d537f1410b0f9e6306bcaf36


cloud_user@dockerhost:~/containerhub$ curl localhost
<html>
<head><title>403 Forbidden</title></head>
<body>
<center><h1>403 Forbidden</h1></center>
<hr><center>nginx</center>
</body>
</html>

cloud_user@dockerhost:~/containerhub$ docker container ls
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS           PORTS                NAMES
f0cd9a64eee8        web                 "nginx -g 'pid /tmp/…"   2 minutes ago       Up 2 minutes        0.0.0.0:80->80/tcp   web01

Dockerfile

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FROM alpine:latest
RUN apk upgrade
RUN apk add nginx
COPY files/default.conf /etc/nginx/conf.d/default.conf
RUN mkdir -p /var/www/html
WORKDIR /var/www/html
COPY --chown=nginx:nginx /files/html/ ,
EXPOSE 80
CMD ["nginx", "-g", "pid /tmp/nginx.pid; daemon off;"]

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30System, Docker
Docker
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