DCEU 18: Developing with Docker Containers
•
0 likes•597 views
Laura Frank Tacho - Director of Engineering, CloudBees Wouldn't it be great for a new developer on your team to have their dev environment totally set up on their first day? What about having the confidence that your dev environment mirrors testing and prod? Containers enable this to become reality, along with other great benefits like keeping dependencies nice and tidy and making packaged code easier to share. Come learn about the ways containers can help you build and ship software easily, and walk away with two actionable steps you can take to start using Docker containers for development.
Report
Share
DCEU 18: Developing with Docker Containers
- 2. @rhein_wein Director of Engineering CloudBees Laura Frank Tacho
- 4. 1 DOCKER COMPOSE BASICS 2 OPTIMIZING IMAGES 3 DEBUGGING IN CONTAINERS
- 5. 1 DOCKER COMPOSE BASICS
- 6. Developer Tools • Docker Compose • Docker Desktop • Docker for Mac • Docker for Windows • Easiest way to run Docker and Kubernetes on your local machine https://www.docker.com/products/docker-desktop
- 7. Sample App: Cats vs Dogs vote result github.com/rheinwein/example-voting-app
- 8. worker .NET vote python redis redis db postgres result node-js Sample App: Cats vs Dogs github.com/rheinwein/example-voting-app
- 9. Use from DockerHub Develop, build, and test Sample App: Cats vs Dogs github.com/rheinwein/example-voting-app worker .NET vote python redis redis db postgres result node-js
- 11. What Happened? example-voting-app $ docker-compose ps Name Command State Ports ------------------------------------------------------------------------------------------------------------------- db docker-entrypoint.sh postgres Up 5432/tcp example-voting-app_result_1 nodemon --inspect=[::]:585 ... Up 0.0.0.0:5858->5858/tcp, 0.0.0.0:5001->80/tcp example-voting-app_vote_1 python app.py Up 0.0.0.0:5000->80/tcp example-voting-app_worker_1 /bin/sh -c dotnet src/Work ... Up redis docker-entrypoint.sh redis ... Up 0.0.0.0:32774->6379/tcp example-voting-app $ docker ps # filtering output CONTAINER ID IMAGE COMMAND STATUS PORTS 7852e34c057f example-voting-app_worker "/bin/sh -c 'dotnet …" Up 6 minutes 3bca5cc2eb09 postgres:9.4 "docker-entrypoint.s…" Up 6 minutes 5432/tcp b0d3c9cd007c example-voting-app_vote "python app.py” Up 6 minutes 0.0.0.0:5000->80/tcp 9702bb12b70b redis:alpine "docker-entrypoint.s…" Up 6 minutes 0.0.0.0:32774->6379/tcp 072da9ac67e3 example-voting-app_result "nodemon --inspect=[…" Up 6 minutes 0.0.0.0:5858->5858/tcp
- 12. What Happened? example-voting-app $ docker-compose ps Name Command State Ports ------------------------------------------------------------------------------------------------------------------- db docker-entrypoint.sh postgres Up 5432/tcp example-voting-app_result_1 nodemon --inspect=[::]:585 ... Up 0.0.0.0:5858->5858/tcp, 0.0.0.0:5001->80/tcp example-voting-app_vote_1 python app.py Up 0.0.0.0:5000->80/tcp example-voting-app_worker_1 /bin/sh -c dotnet src/Work ... Up redis docker-entrypoint.sh redis ... Up 0.0.0.0:32774->6379/tcp example-voting-app $ docker ps # filtering output CONTAINER ID IMAGE COMMAND STATUS PORTS 7852e34c057f example-voting-app_worker "/bin/sh -c 'dotnet …" Up 6 minutes 3bca5cc2eb09 postgres:9.4 "docker-entrypoint.s…" Up 6 minutes 5432/tcp b0d3c9cd007c example-voting-app_vote "python app.py” Up 6 minutes 0.0.0.0:5000->80/tcp 9702bb12b70b redis:alpine "docker-entrypoint.s…" Up 6 minutes 0.0.0.0:32774->6379/tcp 072da9ac67e3 example-voting-app_result "nodemon --inspect=[…" Up 6 minutes 0.0.0.0:5858->5858/tcp 3bca5cc2eb09 postgres:9.4 "docker-entrypoint.s…" Up 6 minutes 5432/tcp db docker-entrypoint.sh postgres Up 5432/tcp
- 13. Text Editor Container Browser Source Code Access local code See changes in the browser immediately
- 14. Accessing Local Code version: "3" services: result: build: ./result command: nodemon server.js volumes: - ./result:/app ports: - "5001:80" - "5858:5858" networks: - front-tier - back-tier Runtime vs Buildtime This will overwrite the code copied into the image at buildtime. Now you’re able to edit local code and have those changes reflected in the container docker-compose.yml
- 16. version: "3" services: redis: image: redis:alpine container_name: redis ports: - "6379" networks: - back-tier def get_redis(): if not hasattr(g, 'redis'): g.redis = Redis(host="redis", db=0, socket_timeout=5) return g.redis vote/app.pydocker-compose.yml Managing External Dependencies
- 17. You don’t need to run your database in a container.
- 18. ‣ If you store application data in the container, that data is lost when the container is stopped and removed ‣ Using volumes allows data to persist beyond the lifecycle of the container ‣ Drivers are available for cloud services ‣ You can also use your local disk Data Volumes services: ... db: image: postgres:9.4 container_name: db volumes: - "db-data:/var/lib/postgresql/data" networks: - back-tier volumes: db-data: docker-compose.yml
- 20. Dockerfiles and container images are the heart of your application. Everything else in the container ecosystem assumes that you have your source code available as a container time.
- 21. FROM node:10.9-alpine RUN mkdir -p /app WORKDIR /app RUN npm install -g nodemon RUN npm config set registry https:// registry.npmjs.org COPY package.json /app/package.json RUN npm install && npm ls && npm cache clean --force && mv /app/node_modules /node_modules COPY . /app ENV PORT 80 EXPOSE 80 CMD ["node", "server.js"] A Dockerfile a list of instructions outlining packages, files, dependencies, and everything required for your application to run. result/Dockerfile
- 22. FROM node:10.9-alpine RUN mkdir -p /app WORKDIR /app RUN npm install -g nodemon RUN npm config set registry https:// registry.npmjs.org COPY package.json /app/package.json RUN npm install && npm ls && npm cache clean --force && mv /app/node_modules /node_modules COPY . /app ENV PORT 80 EXPOSE 80 CMD ["node", "server.js"] Depending on your language, select a suitable base image and then install the packages and run setup commands necessary for your application. In general, aim to have as small of an image as possible, but you can always optimize later. result/Dockerfile
- 23. For faster dev cycles, optimize your images.
- 24. If nothing changes in a layer command, Docker will use an existing version. At buildtime, these cache hits can drastically reduce the time to build and push your image. Cache misses will add extra time, and you can optimize your image to avoid them during development. Use Caching Effectively
- 25. Order Layers for Better Cache Usage Copy over package or dependency manifests and install those before copying the rest of the code. Lockfiles change infrequently, so it’s not necessary to reinstall everything all the time. COPY package.json /app/package.json RUN npm install && npm ls && npm cache clean --force && mv /app/node_modules /node_modules COPY . /app
- 26. Dockerfile Best Practices with Tibor and Sebastiaan Watch the recording when it’s available!
- 27. Pick Base Images Wisely! By now, almost every major language or framework maintains a slim version of their library image, tagged with slim or specifically with alpine. Warning: the size of an image on Docker Hub is the compressed size. hub.docker.com/_/node
- 28. Avoid Anti-Patterns ‣ Simultaneous Innovation ‣ Skipping the fundamentals like giving love to your Dockerfiles ‣ Forgetting other development best practices like pinning dependencies to versions — this stuff still matters even if you’re using containers ‣ For example, don’t use the latest tag
- 29. 3 DEBUGGING IN CONTAINERS
- 30. You can access log output either via Docker Compose or Docker directly. $ docker-compose logs # this returns all logs for all services db | LOG: stats_timestamp 2018-09-12 10:35:03.286676+00 is later than collector's time 2018-09-12 10:35:03.262932+00 for database 12141 result_1 | [nodemon] restarting due to changes... result_1 | [nodemon] starting `node --inspect=[::]:5858 server.js` result_1 | Debugger listening on ws://[::]:5858/f6dd534f-1976-421c-b4e2-8d3b1baf2622 result_1 | For help, see: https://nodejs.org/en/docs/inspector result_1 | App running on port 80 result_1 | Connected to db result_1 | Debugger attached. redis | 1:M 12 Sep 08:33:52.991 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128. redis | 1:M 12 Sep 08:33:52.991 # Server initialized Viewing Log Output
- 31. Viewing Log Output Logs are visible by default when starting your app with docker-compose up. If you prefer a tidy terminal, use up with the -d flag. You can get logs per service later. Tip: timestamps are available with a flag. $ docker-compose up -d ... $ docker-compose logs -t worker # docker logs -t example-voting-app_worker_1 worker_1 | 2018-09-12T08:22:49.367373200Z Waiting for db worker_1 | 2018-09-12T08:22:50.371369500Z Waiting for db worker_1 | 2018-09-12T08:22:53.526120800Z Connected to db worker_1 | 2018-09-12T08:22:53.541336500Z Found redis at 172.20.0.2 worker_1 | 2018-09-12T08:22:53.541400100Z Connecting to redis worker_1 | 2018-09-12T08:33:54.478754500Z Connected to db worker_1 | 2018-09-12T08:33:54.495682400Z Found redis at 172.20.0.2 worker_1 | 2018-09-12T08:33:54.496062600Z Connecting to redis worker_1 | 2018-09-12T08:34:15.528315300Z Processing vote for 'b' by '2d4e42c6c94f4e53' worker_1 | 2018-09-12T08:37:11.883353600Z Processing vote for 'a' by ‘2d4e42c6c94f4e53'
- 32. Starting a Container in Interactive Mode Want a shell to debug startup commands without the container exiting on failure? version: "3" services: web: image: ubuntu:18.04 tty: true stdin_open: true entrypoint: "/bin/bash" docker run -it ubuntu:18:04 /bin/bash # volume mount if you need to with `-v source:target` with docker-compose run web with Docker only
- 33. ‣ docker top will give you a list of all running processes in a container ‣ docker inspect (name | id) will give you ALL of the details about a given resource Helpful Docker Commands ‣ You can use the --format flag and pass in a Go template ‣ For example, to get the IP(s) of a running container: docker inspect --format='{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' $CONTAINER_ID
- 34. Running a Debugger version: "3" services: result: build: ./result command: nodemon --inspect=0.0.0.0:5858 server.js volumes: - ./result:/app ports: - “5001:80" - "5858:5858" networks: - front-tier - back-tier Maintain access to debugging tools by publishing the ports. You may also have to update the command or entrypoint to access debugging tools.
- 36. Visit the CodeShip team at our booth!