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 Docker when 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