Ephemeral storage concern

Hi I want to do programmatic NPM publishes using a Railway service I will need to basically use shell commands to write files to disk, possibly pack them, and then programmatically publish using child processes I guess

My question is in the context of a Railway service, during the lifecycle of the service, can I rely on writing to disk? I understand storage is generally ephemeral so it's all scoped to the deploy of a service, so my question specifically is -- during the lifecycle of a deploy can I rely on writing and reading from disk just like a VM? Any caveats or concerns or specific blog posts I should read?

Thank you