One edge-case, where fpm cannot help by itself, occurs in the python (w/ C-bindings) world, when your dev and prod environments use different libc versions. I got around that issue by running fpm inside a VM, which matches the libc version of the target system.
But it's still not as easy as it can be - so pkgr.io looks promising.
OP here, thanks for the comment. fpm is a great tool: PKGR is based on https://github.com/crohr/pkgr, which itself uses fpm. That being said, you indeed need to make sure your build system is close to your target system, and it is not that easy to package complex apps with specific dependencies. Generally, (Web) Application packaging does not have the same needs as OS packaging.
One edge-case, where fpm cannot help by itself, occurs in the python (w/ C-bindings) world, when your dev and prod environments use different libc versions. I got around that issue by running fpm inside a VM, which matches the libc version of the target system.
But it's still not as easy as it can be - so pkgr.io looks promising.