Docker Weight Loss Tips Rex Roof Blue Newt Software @rexroof github.com/rexroof/docker-weight-loss ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Rex Roof I come from the land of ice and snow. I think about, read about, construct, and eat good food. Using Unix for 25 years. Platform Architect at Blue Newt Software ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Blue Newt Software Startup Studio - we help you create modern software. Working with auto manufacturers, sports leagues, agriculture. We also build and sell our own software. I get to start new projects a few times a year. (and see the same mistakes) ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

What is a Docker container? A way to isolate and package software. A method for wrapping up a single process into a deployable object. Every container should have a single responsibility. A Dockerfile defines a container with a series of instructions. Docker containers are stored in filesystem layers. ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Why worry about the size? - Speed - Quicker CI/CD - faster development - Security - fewer attack surfaces - Storage - Cost, especially at scale. - Also, speed. ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Docker image layers ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● FROM ubuntu COPY cmatrix.tar . RUN tar -xf cmatrix.tar RUN apk add build-base RUN ./configure && make RUN rm -f cmatrix.tar RUN apk del build-base $ docker history 31daae369c43 #(nop) COPY file:312de99 2.03MB tar -xf cmatrix.tar 1.87MB apk add build-base 216MB ./configure && make 442kB rm -f cmatrix.tar 0B apk del build-base 22.4kB ## TOTAL: 226MB

Cached layers are your friend They don’t need to be built again when you’re developing. They don’t need to be uploaded to a registry. They don’t need to be stored in the registry. They don’t need to be downloaded on your deployment server. ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Making better use of layers ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● COPY cmatrix.tar . RUN tar -xf cmatrix.tar \ && apk add build-base \ && ./configure && make \ && rm -f cmatrix.tar \ && apk del build-base $ docker history 31daae369c43 #(nop) COPY file:312de9 2.03MB tar -xf cmatrix.tar && 6.28MB ## Total: 13Mb

Python example that requires compiler ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● FROM python:3.8-slim WORKDIR /app COPY requirements.txt . RUN apt-get update \ && apt-get install -y build-essential libpq-dev \ && pip install -r requirements.txt \ && apt-get remove -y build-essential libpq-dev \ && apt-get -y autoremove && apt-get clean COPY . . CMD [ "python", "start.py" ]

Choose a smaller base image ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● python:latest 933MB python:slim 193MB python:alpine 109MB ruby:latest 842MB ruby:slim 149MB ruby:alpine 54MB

Choose a smaller base image Start small, install what you need. Alpine is small, but use with caution. libc and DNS issues can arise. Spend the time early on to find the right container base and iterate. You have tests, right? ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Use .dockerignore to exclude files - Can save space in your image - Keep secrets out of your containers - Invalidate the cache less frequently $ cat .dockerignore # always ignore .git .git* node_modules build .env .secrets .cache .aws Dockerfile *debug.log* # editor files [._].swp .vscode ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Leverage multi-stage builds - Define multiple docker containers in one Dockerfile - Builds each in order, using the final container in the image - Copy files between containers - You can target individual containers when building ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Using multi-stage builds ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● FROM golang:alpine as build COPY hello.go . RUN go build -o hello hello.go # above is ~350MB FROM alpine as alpine-run COPY --from=build /go/hello /hello CMD ["/hello"] # above is ~7MB - Only your target or final stage is saved in your image. - Each layer still caches locally - Can target higher layers using docker build --target=NAME

Using multi-stage builds ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● # development container FROM node:12.14.1-alpine as development WORKDIR /app ENV HOME /app COPY yarn.lock package.json /app/ RUN npm install COPY public/ /app/public/ COPY src/ /app/src/ EXPOSE 3000 CMD ["npm", "start"] # temp build container FROM development as build ARG NODE_ENV=production ARG GENERATE_SOURCEMAP=false RUN npm run build # production container FROM nginx:1.17.8-alpine as production COPY --from=build /app/build /usr/share/nginx/html

Learn your language packaging options PYTHONDONTWRITEBYTECODE=1 pip install --no-cache-dir python: don’t write cache, don’t create python byte code npm ci --production nodejs: install only production packages, no dev dependencies bundle install --deployment ruby: roll out packages for CI or production use ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Learn your OS install options apt-get install --no-install-suggests -y ubuntu/debian: don’t install suggested packages apk --no-cache add alpine: skip read/write of local package cache yum clean all || apt-get clean all centos/debian/ubuntu: clean up package repo cache files ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

The Docker mindset No longer setting up long-running servers Thinking more about the full lifecycle. Automating your software setup. ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Takeaways - Make your containers smaller - Rearrange your Dockerfile to optimize layers - Review your .dockerignore files - Respect the layer cache - Your container is not a VM github.com/rexroof/docker-weight-loss ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Thanks! ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● github.com/rexroof/docker-weight-loss @rexroof gdl@rexroof.com