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docker (Docker Deep Dive (image (image layers (instructions on how to…

- - - - the blueprint file which specifies how to create your image and link them up
        Commands that create content will create new Layers
      - FROM <<imageName>>
      - RUN <<runCommand>>
      - WORKDIR <<dir>>
      - COPY ./from ./to
      - CMD ["npm", "start"]
      - DEMO FILE:
        
        # find public images on hub.docker.com FROM node:8.11.3 # run commands like you would in linux terminal RUN mkdir -p /usr/src/app # sets a default working directory for later commands WORKDIR /usr/src/app # copies all files from the directory where Dockerfile was located # to directory inside the docker container COPY . /usr/src/app # the port that the container will open to the outside EXPOSE 4200 # run any other commands if you require it... this is for angular RUN npm rebuild node-sass # command to start your container, could be ["node", "server.js"] etc... CMD ["npm", "start"]
      - LABEL maintainer="someone@gmail.com"
    - - acts like .npmignore or .gitignore
        generally node_modules would reside in here
    - - docker image build -t <imageName> gitRepoUrl
    - - Multiple From Commands
        
        FROM node:latest as store WORKDIR /usr/src/app COPY react-app . RUN npm install RUN npm run build FROM maven:latest as server WORKDIR /usr/src/serv COPY pom.xml . RUN mvn - B -f pom.xml -s /usr/share/maven/ref/settings-docker.xml dependency:resolve COPY . . RUN mvn -b -s /usr/share/maven/ref.settings-docker.xml package -DskipTests FROM java:8-jdk-alpine AS production RUN adduser -Dh /home/gordon gordon WORKDIR /static COPY --from=store /usr/src/app/ . WORKDIR /app COPY --from=server /usr/src/server/target/Server.jar . ENTRYPOINT ["java", "-jar", "/app/Server.jar"] CMD ["--spring.profiles.active=postgres"]
        
        node / maven are the factories
        the npm run build / maven -b commands make the products
        products are shipped to the java image, not the factories
  - - - Kernel Primitives
        
        namespaces
        
        used to carve up an OS into containers
        
        process id
        network
        filesystem
        inter-proc comms
        UTS
        User
        
        cgroups
        
        resource allocation for containers
        
        used to build containers
      - isolated area of OS with resource usage limits
  - - - Client
        
        Daemon
        
        containerD
        
        runc
        
        for every container you create, you get a runc process / shim that connects back up to containerD
        
        non-daemon process
        
        daemon process
      - Client
        windows: docker.exe
        
        Daemon
        windows: dockerd.exe
        
        Compute Services
        
        Native Windows Containers
        
        many namespaces on the host kernel
        
        Hypver-V Containers
        
        can be linux / windows
        
        isolated VM's with it's own kernel
    - - namespace / cgroups were originally controlled by an external tool called LXC
        would break things when updates were made
        no control
        started building libcontainer in house to replace LXC
        Docker is born
      - kubernetes is a container orchestrator
        wanted to use docker, but docker had become bloated and came with it's own orchestrator
      - open container initiative
        
        image spec
        
        runtime spec
        
        standardization + docker refactor
      - Client
        Daemon
        containerD
        OCI interface with Kernel
        
        Linux
        Client Calls
        Daemon
        containerD
        runc
        vanilla implementation of OCI on linux
        
        Windows
        Client Calls
        Daemon
        Compute Services
        though it's different
        API is the same
  - - - instructions on how to create an image
      - doesn't know about other layers of the image
      - you'll notice this when you pull an image from docker hub, it'll have multiple hashes for each layer you are pulling
        
        step 1: Get manifest
        
        step 2: Pull layers
  - - - can refer to the latest stable release
    - - uncompressed layers
    - - compressed layers
        
        when pushing / pulling
    - - use official images
      - keep images small
      - add your app on official images
      - be specific with image tag, don't use latest in prod
- - - - <<imageName>>
        
        -v $(pwd):/directory/to/map
        
        creates a bind mount
        
        pwd current directory
    - - <<containerName>>
        
        bash -it
        
        enters container
        
        'exit' to exit container
  - - - -t
        
        <<dockerUserName>>/image-name
        
        .
        
        builds an image from the Dockerfile in the current directory