Serving under a sub-path

To host the console at something like example.com/barakocms, set BARAKO_BASE_PATH on the published image. No rebuild, and the same image still serves the domain root when the variable is unset:

docker run -e BARAKO_BASE_PATH=/barakocms -e NEXT_PUBLIC_API_URL=https://example.com/api \
  -p 3000:3000 ghcr.io/baryodev/barako-brew:latest

Then proxy /barakocms/ to the container. Next.js 308-redirects /barakocms/ to /barakocms, so an nginx rule redirecting the other way will loop. Proxy the bare path instead of redirecting it.

The value is one or more /segments of letters, digits, dot, underscore, tilde or hyphen, with no trailing slash. It ends up in JavaScript, JSON and HTML, so anything else is refused at start.

Next.js resolves basePath and assetPrefix during the build, which is why this cannot simply be read from the environment at run time. The image is built against a placeholder prefix and entrypoint.sh writes the real one into the build output before the server starts. The cost is a second or so of startup; the gain is one published image for every site.

--build-arg NEXT_BASE_PATH=/barakocms still bakes a path in at build time for anyone who wants that. An image built that way ignores BARAKO_BASE_PATH, and says so in its startup log.