the error means you have a railpack-plan.json or railpack.json file that lists "spring" in the secrets array, but there's no variable called "spring" set in your railway service.

to solve this either add a "spring" variable in railway's variables tab, or remove "spring" from the secrets array in your config file.

BUT for spring boot apps, railway auto-detects everything and you probably don't need any railpack config file at all. try deleting railpack-plan.json / railpack.json completely and let railway handle it automatically

I don't have any railpack config files in my repo. Seems like the build process is generating it's own railpack-plan.json file. Is there a way to inspect the contents of this generated file to debug ?

yes you can, the generated railpack-plan.json content shows up in your build logs. look for the section right BEFORE the line that says "load build definition from railpack-plan.json"

it'll show something like:

Packages
──────────
Steps
──────────
Deploy
──────────
Successfully prepared Railpack plan for build

if there's a secret called "spring" in the plan, it would be listed there.

also check if you have a Dockerfile in your repo with --mount=type=secret,id=spring or any references to ${spring} in your application.properties or application.yml files

if you find where "spring" is being referenced, you either need to add a "spring" variable in railway, or remove/fix that reference

There were no variables called spring but there were variables that started with 'spring.' The dot '.' was the issue finally !! I replaced them with underscores _ and all was good. They were correctly referenced by my Spring app. Thanks for your help.

i'm always happy to help