Add IOG nix cache in flake configuration

[yvan-sraka]

From https://nixos.org/manual/nix/unstable/command-ref/new-cli/nix3-flake.html#flake-format

nixConfig: a set of nix.conf options to be set when evaluating any part of a flake. In the interests of security, only a small set of whitelisted options (currently bash-prompt, bash-prompt-prefix, bash-prompt-suffix, and flake-registry) are allowed to be set without confirmation so long as accept-flake-config is not set in the global configuration.

[yvan-sraka]

bors try

[iohk-bors[bot]]

try

Timed out.

[yvan-sraka]

The issue here is that interactive user confirmation of using IOG cache currently stuck the CI … solutions could be to:

• add IOG cache to global Nix configuration of CI (if such thing possible?)
• tweak CI scripts to pass the desired interactive input (or find the Nix non-interactive CLI option)

[yvan-sraka]

bors try

[hamishmack]

It looks like this has broken one of the old build kite tests that was actually using the flake. It now asks for input from user.

See https://buildkite.com/input-output-hk/haskell-dot-nix/builds/7008#0182d985-68d6-4650-a955-8975b87c9ae8

[hamishmack]

bors try-

[yvan-sraka]

I could add the same local nix.conf hack to another shell script or give a try to:

yes | nix build .#roots.x86_64-linux --option allow-import-from-derivation false

[hamishmack]

bors try

[hamishmack]

bors try-

[hamishmack]

bors try

[hamishmack]

bors try

[iohk-bors[bot]]

try

Already running a review

[hamishmack]

bors try-

[hamishmack]

bors try

[hamishmack]

bors try

[iohk-bors[bot]]

try

Already running a review

[hamishmack]

bors try-

[hamishmack]

bors try

[hamishmack]

bors try-

[hamishmack]

bors try-

[hamishmack]

bors try

[hamishmack]

Oh it started #1601.

[iohk-bors[bot]]

try

Build succeeded:

• buildkite/haskell-dot-nix
• ci/hydra:Cardano:haskell-nix:required