DevOps Classroom Series – 05/Sept/2021

Viewing Docker Logs

• docker container logs can be viewed by the command docker container logs <container name>
• All the logs and errors redirected to STDERR and STDOUT stream
• Docker supports different logging drivers Refer Here

Constraints on Docker containers

• By default docker container has no resource restrictions and it can use as much of resources given by the host kernel
• We can restrict memory and cpu while starting a container

docker container run --name memjenkins -P -d --memory 1024m jenkins/jenkins

• now execute docker stats
• similarly
  • –memory-swap
  • –memory-reservation
  • –memory-swappiness
• We can also restrict cpu’s as well

docker container run --name memcpujenkins -P -d --memory 1024m --cpus="2" jenkins/jenkins

Game of life multi stage build

• Docker file

FROM maven:3-openjdk-8 as builder
RUN git clone https://github.com/wakaleo/game-of-life.git && cd game-of-life && mvn package

FROM tomcat:9.0-jdk8
COPY --from=builder /game-of-life/gameoflife-web/target/gameoflife.war /usr/local/tomcat/webapps/gameoflife.war
EXPOSE 8080

Using ENV in CMD

• Dockerfile

FROM ubuntu
ENV DURATION=1d
CMD ["/bin/bash", "-c", "sleep ${DURATION}"]

Exercise

• Learn JSON and YAML Refer Here