Using Environment Variables baked at Build Time

Use Branch: cra-buildvars
https://create-react-app.dev/docs/adding-custom-environment-variables/

1. Create env variables with prefix REACT_APP_
2. Have a .env file but don't put it in version control
3. Use process.env.<ENV_VAR_NAME> in the code
4. Or, Use %ENV_VAR_NAME% in the HTML code
5. Run npm run start or npm run build and inspect the generated static files
6. Problems: Cannot follow build once, and deploy many approach. Every environment needs a different build.

Using Environment Variables within nginx docker containers

Use Branch: envars

1. Have a templated config for constants outside the core code
2. Have a .env file but don't put it in version control
3. envsubst utility is bundled with alpine docker image
4. Provide environment variable values at the run time (docker run --env MYVAR1=foo)
5. Local environments: Use .env.local files along with a npm utility called envsub that works almost similar to envsubst above.

Generate Dependency List and healthchecks for nginx docker containers

Use Branch: deps

1. Generate a healthz.json using the following command during the build
   npm ls --depth=0 --json | jq ".status=\"green\"|.buildDate=\"$BUILD_DATE\"|.gitHash=\"$GIT_HASH\"" > healthz.json

2. Configure nginx route for the /healthz path