layout: true class: center, middle --- ## Docker 101 By David Soff --- ## Before I start please clone <https://github.com/Davidsoff/docker101> for the hands-on part --- ## What is Docker? - Lightweight containers - Only share the kernel of the host - Smaller and quicker to start than VMs - typically only runs a single proccess --- ## Docker vs VM  --- ## Architecture  --- ## How to use Docker? Download it from [docker.com](https://www.docker.com/get-started/) --- ## Anatomy of a Dockerfile Dockerfile is built in layers Every line in the file is a layer that has a unique hash. This means layers can be reused between builds. --- ## A simple Dockerfile ```Dockerfile FROM nginx:alpine COPY html /usr/share/nginx/html EXPOSE 80 ``` --- ## Building images ```bash docker build -t my-image . ``` ??? docker build looks for Dockerfile in the context directory by default --- ## running images ```bash docker run --name my-container -p 8080:80 my-image ``` --- ## viewing containers ```bash docker ps ``` --- ## stopping images ```bash docker kill my-container ``` --- ## Hands-on time --- ## Static application simple serving of html files ```Dockerfile FROM nginx:alpine COPY html /usr/share/nginx/html EXPOSE 80 ``` `docker build -t static .` `docker run -p 3000:80 static` --- ## Dynamic application simple customised Hello World spring boot application ```Dockerfile FROM gradle:alpine ADD awesome_application . RUN gradle build ENV JAVA_OPTS="" EXPOSE 8080 ENTRYPOINT exec java $JAVA_OPTS -jar build/libs/app.jar ``` ??? `docker build -t dynamic .` `docker run -p8080:8080 dynamic ` --- ## Container orchestration - Docker compose Lightweight container orchestration, Excelent for local development - Kubernetes Production grade container orchestration. --- ## Multi container setup - Applications need storage - One process per container ## Docker compose configuration ### **`compose.yaml`** ```yaml version: '3' services: application: build: . ports: - "4001:4000" depends_on: - postgres postgres: image: "postgres:alpine" environment: - POSTGRES_PASSWORD=postgres - POSTGRES_USER=postgres - POSTGRES_DB=multi_container_application_dev ``` `docker compose up --build` `docker compose down` --- ## Multistage builds - Separates build environment and runtime environment - Optimised containers for each role - Allows for very small containers ## Multistage example ```Dockerfile FROM gradle:alpine AS builder ADD awesome_application . RUN gradle build FROM openjdk:jre-alpine ENV JAVA_OPTS="" COPY --from=builder /home/gradle/build/libs/app.jar /app/app.jar EXPOSE 8080 ENTRYPOINT exec java $JAVA_OPTS -jar /app/app.jar ``` ??? `docker build -t multistage .` `docker run -p8080:8080 multistage` --- ## Questions? --- ## Thank you