Activity 3 Contd
- Inspecting the Images created, one extra layer is added as a result of the ADD instruction
- The final Dockerfile which we have used is
FROM openjdk:11.0.13-jre-slim
LABEL author="khaja"
ADD https://referenceapplicationskhaja.s3.us-west-2.amazonaws.com/spring-petclinic-2.4.2.jar /spring-petclinic.jar
EXPOSE 8080
CMD [ "java", "-jar", "/spring-petclinic.jar" ]
Activity 4
- Containerize an application which runs on tomcat 8 server
- Manual Steps:
- Ensure JAVA 8 is installed
- Ensure Tomcat 9 is installed
- COPY the game-of-life.war in the webapps folder of tomcat8
- tomcat runs on port 8080 by default
- Refer Here for the changes done
- Now build the image
- Now let run the container with newly builded image
- Now navigate to openport and add
/gameoflife
- Exercise: Try building a slim version of gameoflife with 9 and jdk you can probably use
tomcat:9-jdk8-openjdk-slim
Activity 5
- Create a Docker container with any base image of your choice which will print
Hello Dockerwhen the container is STARTED
FROM alpine
CMD ["echo", "Hello Docker"]
- Lets do some experiments
- Whatever is written in CMD can be overriten by passing arguments after image name in docker container run
docker container run actvity5:1.0 <any command> - Now consider the following dockerfile
FROM alpine
ENTRYPOINT ["echo"]
CMD ["Hello Docker"]
* ENTRYPOINT is the fixed command that gets started when container is created and cannot be overriten whereas whatever is written in CMD can be overriten
Activity 6
- Create a docker container that will print all the environment variables when container is started
- Solution
FROM alpine
CMD set
- Now run the container
- Lets add one instruction
FROM alpine
ENV MY_NAME=activity6
CMD set
* If your application depends on any ENV variables, we can add them by using the Dockerfile using ENV instruction.
* We can also change the ENV variable while creating the container
