Managing depends lists?

[polarathene]

TL;DR: When overrides is not viable (same package format, different arch, different packages), how do you manage multiple package differences? (different packages, different number of packages)

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• A package of the same format can have different package names to depend on depending on distro / release installing the package.
• The nFPM docs only show the YAML syntax for individual list items prefixed with -, but the [ ... ] syntax also works.
• When package lists are symmetrical you can use ENV more easily to provide appropriate names, but bit problematic when asymmetrical?

ENV:

# Fedora RPM depends (attempted to provide YAML array list as full value string, rejected):
#REQUIRED_PACKAGES="[ragel, openssl, glib2, sqlite, file-libs, libicu, pcre, zlib, libsodium, luajit, hyperscan]"
# openSUSE RPM depends (attempted to provide YAML array list as items only and wrap ENV in `nfpm.yaml`, rejected):
REQUIRED_PACKAGES="ragel, openssl, glib2, sqlite, libmagic1, libicu, pcre, zlib, libsodium, luajit"
# Example of arch dependent packages:
# x86_64:
REQUIRED_PACKAGES="${REQUIRED_PACKAGES}, hyperscan-devel, jemalloc"
# aarch64:
REQUIRED_PACKAGES="${REQUIRED_PACKAGES}, vectorscan-devel"

nfpm.yaml (neither works):

#depends: ${REQUIRED_PACKAGES}
depends: [ ${REQUIRED_PACKAGES} ]

What is the right way to approach this? Do you stitch several YAML files together to provide config, or commit several different config copies with common content repeated?

• AMD64 vs ARM64 differences (overrides feature doesn't seem like it supports this)
• Differences for same package format (overrides feature doesn't seem like it supports this)
• Variants (alternative builds for the same platform + package, but compiled with different build flags)

cue or ytt seem like they might be a bit overkill for this, but the ENV expansion also doesn't seem suitable? Am I better to provide overrides with external context instead? Such as sed to replace the depends: line with a YAML list value?

I haven't tried YAML anchors + aliases yet, perhaps I could store the values in nfpm.yaml that way and use an ENV to switch 🤔

[polarathene]

• Empty items (works): It seems I can have empty list items, but placing ENV to provide values there may need a generic name if it could represent various packages..
• Anchors/Aliases (doesn't work): nfpm.Config seems to get validated, any foreign keys defined (even if using the convention of x- prefix like Docker offers for extensions) throws an error.
• yq could be used to modify YAML via shell scripts in CI.
• envsubst seems to be the advised alternative to replace file content ENV vars before nfpm processes the config. This was the simplest approach for bulk replacing the depends for me 👍