Developer Experience Wishlist

So far, we have focused primarily on getting our container images ready for deploying to production, and haven't focused on the developer experience.

Key DevX Features:

1. Easy/simple to set up: Using docker compose, we can define the entire environment with a single yaml file. To get started, team members can issue a single command make compose-up-build or make compose-up-build-debug depending if they want to run the debugger or not.

2. Ability to iterate without rebuilding the container image: In order to avoid having to rebuild the container image with every single change, we can use a bind mount to mount the code from our host into the container filesystem. For example:

- type: bind
  source: ../05-example-web-application/api-node/
  target: /usr/src/app/

3. Automatic reloading of the application:

   • React Client: We are using Vite for the react client which handles this handles this automatically
   • Node API: We added nodemon as a development dependency and specify the Docker CMD to use it
   • Golang API: We added a utility called air (https://github.com/cosmtrek/air) within Dockerfile.dev which watches for changes and rebuild the app automatically.

4. Use a debugger:

   • React Client: For a react app, you can use the browser developer tools + extensions to debug. I did include react-query-devtools to help debug react query specific things. It is also viewed from within the browser.
   • Node API: To enable debugging for a NodeJS application we can run the app with the --inspect flag. The debug session can then be accessed via a websocket on port 9229. The additional considerations in this case are to specify that the debugger listen for requests from 0.0.0.0 (any) and to publish port 9229 from the container to localhost.
   • Golang API: To enable remote debugging for a golang application I installed a tool called delve (https://github.com/go-delve/delve) within ./api-golang/Dockerfile.dev. We then override the command used to run the container to use this tool (see: docker-compose-debug.yml)

5. Executing tests: We also need the ability to execute our test suites within containers. Again, we can create a custom docker-compose-test.yml overlay which modifies the container commands to execute our tests. To build the api images and execute their tests, you can execute make run-tests which will use the test compose file along with the dev compose file to do so.

6. Continuous integration pipeline for production images

7. Ephemeral environment for each pull request

In the following lessons we will address all of these!