This makes it clearer what variables actually need to be set
locally, and which have been forgotten. It also makes the build
simpler, by removing the need to copy the .env-dist file.
This should be safe to apply, since .env-dist already got loaded by
default, just like .env now is. And it is still the case that
actual environment variables overwrite the ones in the .env file.
For non-Next.js setups (e.g. cron jobs or database migrations), I
switched to dotenv-flow. The regular dotenv explicitly avoids
inheritance [1], because it wants environment variables to be
specific to an environment. That was already not the case with most
of our environment variables, so the switch makes sense for us.
Next steps could be to remove unused variables from .env, and
possibly moving variables with local/stage-specific values to
.env.local.example, though that riskier, since environments might
depend on those being present.
[1]
https://www.npmjs.com/package/dotenv#should-i-have-multiple-env-files
Vincent