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![© 2018 All Rights Reserved. !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](https://image.slidesharecdn.com/jenkinsworlddevopsworld-180919000711/75/Using-Docker-For-Development-11-2048.jpg)
![© 2018 All Rights Reserved. !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](https://image.slidesharecdn.com/jenkinsworlddevopsworld-180919000711/75/Using-Docker-For-Development-12-2048.jpg)
![© 2018 All Rights Reserved. !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"] A Dockerfile a list of instructions outlining packages, files, dependencies, and everything required for your application to run. result/Dockerfile](https://image.slidesharecdn.com/jenkinsworlddevopsworld-180919000711/75/Using-Docker-For-Development-22-2048.jpg)
![© 2018 All Rights Reserved. !23 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](https://image.slidesharecdn.com/jenkinsworlddevopsworld-180919000711/75/Using-Docker-For-Development-23-2048.jpg)
![© 2018 All Rights Reserved. !28 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"] Each of these instructions results in a layer in your image. More layers means a bigger image, which means: ‣ Longer builds ‣ Longer to push ‣ Longer to pull result/Dockerfile](https://image.slidesharecdn.com/jenkinsworlddevopsworld-180919000711/75/Using-Docker-For-Development-28-2048.jpg)
![© 2018 All Rights Reserved. !34 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](https://image.slidesharecdn.com/jenkinsworlddevopsworld-180919000711/75/Using-Docker-For-Development-34-2048.jpg)
Uploaded byLaura Frank Tacho
Using Docker For Development
The document provides a comprehensive guide on using Docker for development, covering Docker Compose basics, image optimization, and debugging within containers. It emphasizes the importance of selecting the right tools, managing dependencies, and optimizing Dockerfiles for efficient development cycles. The document also includes practical examples and commands for managing Docker containers and streams, particularly in the context of a sample voting application.
Using Docker For Development
- 1. Using Docker forDevelopment
- 2. © 2018 AllRights Reserved. LAURA FRANK TACHO Director of Engineering, CloudBees
- 3. © 2018 AllRights Reserved. !3landscape.cncf.io
- 4. © 2018 AllRights Reserved. !4 1 DOCKER COMPOSE BASICS 2 OPTIMIZING IMAGES 3 DEBUGGING IN CONTAINERS
- 5. © 2018 AllRights Reserved. !5 1 DOCKER COMPOSE BASICS
- 6. © 2018 AllRights Reserved. Picking the Right Tools TOO LOW LEVEL TOO COMPLEX OR ABSTRACTED Building container images by hand Running one-off containers docker run commands that are wider than a terminal window Deploying every single code change Setting up a multi-node cluster Complicated READMEs or setup instructions App declaration that is easy to read and edit Access to logs Ability to mount source code Common tooling with minimal setup Docker Compose
- 7. © 2018 AllRights Reserved. !7 Sample App: Cats vs Dogs vote result github.com/rheinwein/example-voting-app
- 8. © 2018 AllRights Reserved. !8 worker .NET vote python redis redis db postgres result node-js Sample App: Cats vs Dogs
- 9. © 2018 AllRights Reserved. !9 Use from DockerHub Develop, build, and test worker .NET vote python redis redis db postgres result node-js Sample App: Cats vs Dogs
- 10. © 2018 AllRights Reserved.
- 11. © 2018 AllRights Reserved. !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. © 2018 AllRights Reserved. !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. © 2018 AllRights Reserved. !13 Text Editor Container Browser 😎 Source Code
- 14. © 2018 AllRights Reserved. !14 Accessing Source 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 see updates in the browser instantly. docker-compose.yml
- 15. © 2018 AllRights Reserved.
- 16. © 2018 AllRights Reserved. !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. © 2018 AllRights Reserved. !17 You don’t need to run your database in a container.
- 18. © 2018 AllRights Reserved. !18 ‣ Containers are meant to be ephemeral. If you store application data in the container, that data is lost when the container is stopped and removed ‣ Using volumes allows data to stick around outside of the lifecycle of the container ‣ Many drivers are available for cloud services ‣ You can also use your local disk Data Volumes
- 19. © 2018 AllRights Reserved. !19 ‣ 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 ‣ Many 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. © 2018 AllRights Reserved. !20 2 OPTIMIZING IMAGES
- 21. © 2018 AllRights Reserved. !21 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. Virtually every type of application can run inside a container.
- 22. © 2018 AllRights Reserved. !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"] A Dockerfile a list of instructions outlining packages, files, dependencies, and everything required for your application to run. result/Dockerfile
- 23. © 2018 AllRights Reserved. !23 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
- 24. © 2018 AllRights Reserved. !24 For faster dev cycles, optimize your images.
- 25. © 2018 AllRights Reserved. !25 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
- 26. © 2018 AllRights Reserved. !26 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
- 27. © 2018 AllRights Reserved.
- 28. © 2018 AllRights Reserved. !28 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"] Each of these instructions results in a layer in your image. More layers means a bigger image, which means: ‣ Longer builds ‣ Longer to push ‣ Longer to pull result/Dockerfile
- 29. © 2018 AllRights Reserved. !29 Chain RUN Commands Reducing the number of layers will reduce the overall size of your image, even if the output is the same. COPY package.json /app/package.json RUN npm install && npm ls && npm cache clean --force && mv /app/node_modules /node_modules COPY . /app COPY package.json /app/package.json RUN npm install RUN npm ls RUN npm cache clean --force RUN mv /app/node_modules /node_modules COPY . /app 92MB83.9MB
- 30. © 2018 AllRights Reserved. !30 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
- 31. © 2018 AllRights Reserved. !31 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
- 32. © 2018 AllRights Reserved. !32 Laura’s Model for Super Duper Container Success Get it running in a container. Create an application template and get that running. Then optimize your Dockerfile. Then worry about everything else.
- 33. © 2018 AllRights Reserved. !33 3 DEBUGGING IN CONTAINERS
- 34. © 2018 AllRights Reserved. !34 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
- 35. © 2018 AllRights Reserved. !35 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 detached 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'
- 36. © 2018 AllRights Reserved. !36 Tip: set many options on Docker Compose directly, not on subcommands. --verbose Show more output --log-level LEVEL Set log level (DEBUG, INFO, WARNING, ERROR, CRITICAL) Debugging Compose Itself
- 37. © 2018 AllRights Reserved. !37 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
- 38. © 2018 AllRights Reserved. !38 ‣ 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
- 39. © 2018 AllRights Reserved. !39 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.
- 40. © 2018 AllRights Reserved. !40
- 41. Visit the CodeShipteam at our booth!