DOCKER

1. Building a docker image
   1. Write a Dockerfile
   2. Build a docker image
2. Running containers
   1. Running and stopping containers
   2. Exposing ports and
   3. Mouting volumens for data persistence
      1. Application configuration
      2. Log management
      3. Persistent storage
      4. File uploads
      5. Dev environments
      6. Data backup
      7. Data sharing
   4. Env variables and configuration
3. Containers management
   1. Running containers
   2. Inspect containers
   3. Delete containers and images
4. Docker compose
   1. docker-compose.ym
   2. Running apps
5. Optimization and best practices
   1. Reduce the container size
   2. Dockerfile layers
   3. Security
6. CI/CD
   1. Integrate Docker in CI/CD pipelines
   2. Integrate Docker with Github Actions
7. Networking in Docker
   1. Communication among containers
8. Docker Swarm and Kubernetes
   1. Osquestating with Docker Swarm
   2. Kubernetes for advanced orchestration
9. Docker on production
   1. Deployment strategies
   2. Logging and monitoring containers
      
      
      

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1. Building a docker image

• Having a Dockerfile is mandatory

./mvnw clean package

docker build -t demo-springboot-docker .

2. Running containers

2.1 Running and stopping containers

docker run -p 8080:8080 demo-springboot-docker

• Stop and delete docker container

docker ps -a
docker stop <container id>
docker rm <container id>

• Stop and delete docker images

docker images
docker rmi <image_id>

Running the docker container in sync with code changes

---

* We are going to mount the volumen where source code will be left. * We will need to add the devtools dependency

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-devtools</artifactId>
	<optional>true</optional>
</dependency>

• We will need to ask spring boot to consider reloading the app

spring.devtools.restart.enabled=true
spring.devtools.livereload.enabled=true

0. The Dockerfile should avoid using COPY and instead of using java -jar we will use sprint boot command:

FROM ...
WORKDIR ...
EXPOSE ...
ENTRYPOINT ["./mvnw", "spring-boot:run"]

1. Initial build is mandatory, it will happen just once

docker build -t demo-springboot-docker .

2. Run the docker container with the mounted volumen

docker run -p 8080:8080 -v $(pwd):/app demo-springboot-docker

3. Containers management

docker ps [-a]
docker inspect [container_id]
docker stop [container_id]
docker start [container-id_or_name]
docker rm [-f] [container_id]
docker images
docker rmi [image_id]
docker container prune [-a]
docker volume prune
docker logs [container_id]
docker exec -it [container_id] /bin/bash

4. Docker compose

For this simple example and aiming to demonstrate its applicatiblity without adding an extra service like a database, we duplicated the service. Bear in mind that this docker-compose.yml file and the nginx.conf both are develop env oriented just to not complicate the whole example.

5. Optimization and best practices

• Optimization related to using stages to build the final images.
• Changing the ownership: As shown in the Dockerfile, it was added a group and a new user added to that group, which will be the owner.

5.3 Security:

It could be csonsidered using Selinux or apparmor.