This tutorial will guide the reader to create a Docker image with apache web server running on a CentOS operating system.
If you are new to Dockers, please click here to access the installation and basics document.
Create a new folder named /sandbox/docker
[root@docker1]# mkdir /sandbox/docker
Go to the created folder /sandbox/docker
[root@docker1]# cd /sandbox/docker
Create a file named “.Dockerfile” with the following lines in italics:
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# FROM is the base image to be used
#RUN to run a command before creating the final image
RUN yum -y install httpd
RUN echo “Welcome to my webpage” > /var/www/html/index.html
# COPY to copy a file present in the localhost to the filesystem inside the new image
COPY ./shiju.txt /home
#Command to be run after deploying the comainter with the image
ENTRYPOINT [“/usr/sbin/httpd”, “-D”, “FOREGROUND”]
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- The FROM parameter tells what should be the base image to be used
- The RUN parameter says what commands needs to be run on the base image before we build the new image
- The CMD parameter says what command needs to be run when the container will be deployed using the new image
- The WORKDIR is a parameter that can be used to mention the working directory based on which the remaining command/statements needs to be run
Now let us build the initial build named “centos_1” using the “.Dockerfile” file:
[root@docker1 docker]# docker build -t centos_http -f .Dockerfile .
The -t is the parameter to tag the image
Now let us run the image, binding port 1337 to view the webpage
[root@docker1 docker]# docker run -it -p 1337:80 –name myContainer centos_http
You should be able to access the default apache web page by accessing “http://<base host IP>:1337” using a web browser.
The switch -p enables all connections coming to TCP port 1337 of the system hosting the docker to be mapped to port 80 of the new container being deployed.
Tagging the image:
Another way of tagging the same build image was by running the command:
[root@docker1 docker]# docker build -t shiju_docker_id/redis1:latest -f .Dockerfile3 .
Here latest is the version number, which is normally written as latest.
[root@docker1 docker]# docker ps -all
The way to deploy a container using the image is as follows.
[root@docker1 docker]# docker run shiju_docker_id/redis1
Theoretically the version number is the actual tag.