nix build --all: build all packages in a flake

[domenkozar]

There's currently no way to build all packages in a flake, a quite common operation that was previously just nix-build.

You can see here people struggling: https://www.reddit.com/r/NixOS/comments/vohopf/is_there_an_easy_way_to_build_all_the_packages_of/

[bjornfor]

A possible workaround is to add all packages as "checks" and then "nix flake check" will build all.

[NorfairKing]

Related: #7157 (comment)

[martyall]

There is also a workaround using symlinkJoin and defining an all default package. You can find an example of this in this article in the section titled "The Flake"

[hsjobeki]

just ran into the same issue.
what if we could just add the --all feature to flakes which builds all packages as expected?

[carlthome]

just ran into the same issue.
what if we could just add the --all feature to flakes which builds all packages as expected?

That's what I assumed already existed, at least.

Or, when no default package is set, that "nix build" would build everything.

[bobvanderlinden]

What should be the output of --all? For instance, should it result in a bunch of result-{1,2,3,4,5} symlinks?

[hsjobeki]

What should be the output of --all? For instance, should it result in a bunch of result-{1,2,3,4,5} symlinks?

Good question. I guess this would clutter your workspace on larger package sets.
I‘d like a folder in the nix store which holds a list of symlinks to every single package

[bobvanderlinden]

So it'll basically implicitly create a new derivation using --all?

linkFarm [
  { name = "packagea"; path = packages.${system}.packagea }
  { name = "packageb"; path = packages.${system}.packageb }
  { name = "packageb"; path = packages.${system}.packageb }
]

Resulting in a result symlink:

result/packagea -> /nix/store/...-packagea/
result/packageb -> /nix/store/...-packageb/
result/packagec -> /nix/store/...-packagec/

---

I'm not sure I like the approach, as it is non-transparent if Nix is going to build derivations implicitly.

It could also be a convention or even a default to make packages.${system}.default or packages.${system}.all use the linkFarm approach. If it was a convention, a helper function that creates a 'package set' derivation would be useful.

Then it would work without needing a --all option.

[aciceri]

I don't like it, shouldn't have to depend on nixpkgs in my opinion. Moreover derivations can have multiple outputs (can't remember how nix build manages it currently, not even sure it does).

[bobvanderlinden]

What do you think is the better approach to solve the issue?

shouldn't have to depend on nixpkgs in my opinion

There could also be a builtin for creating a 'package set', but I would agree is it's not ideal.

Moreover derivations can have multiple outputs

Indeed, that's why I thought earlier that it would output result-{1,2,3,4,5}.

Would it output result-{packagea,packageb,packagec} instead?

[aciceri]

I meant multiple outputs per single derivation, so something like result-{drvName}-{outputName}.