• The nextjs env var can only be set at build time. And it replaces process.env so env var can't be read at runtime. The disadvantages are:
  • Each build-arg need to be specified when building
  • The image (which is public) will have these variable values
  • If you have multiple environments (e.g. development), you need to compile multiple images (with diff tags)
• So this entrypoint.sh will read the environment variables and replace the nextjs compiled file

issue:
vercel/next.js#17641

https://raphaelpralat.medium.com/system-environment-variables-in-next-js-with-docker-1f0754e04cde