Auto update hashes in nix

[brianmay]

Purpose of this bug report is to document my current findings on this issue in a public place.

I would like a script that can automatically update the hashes in the flakes.

teslamate/flake.nix

Line 27 in 9b2de5f

hash = "sha256-CeGtWKLjZJsoHk+uSAIz8s46XyGJWa3ECm5rSRfqlrc=";

teslamate/flake.nix

Line 35 in 9b2de5f

npmDepsHash = "sha256-05AKPyms4WP8MHBqWMup8VXR3a1tv/f/7jT8c6EpWBw=";

Here is a solution for npm: https://sitr.us/2024/03/08/nix-npm-and-dependabot.html/

Mix is the problem, I don't know obtain the new hash without building with fakeHash, and then replacing the hash with the hash in the error.

Google search showed me this project which attempted to solve this problem argoproj/argo-workflows#12520 with the following shell script:

# this is reliant on the vendorHash being on line 195
sed -i '195s/vendorHash = \"\([^\"]*\)\"/vendorHash = ""/g' ./dev/nix/flake.nix
NIX_HASH=$(nix --log-format raw build ./dev/nix 2>&1 | grep  "got: " | awk '{ split($0,a,"got:    "); print a[2] }')
sed -i '195s|vendorHash = \"\([^\"]*\)\"|vendorHash = "'$NIX_HASH'"|g' ./dev/nix/flake.nix
echo "Changed Nix hash to : $NIX_HASH"
rm -rf result

Unfortunately this is broken, it will try to build the project with the old hash, and if the old hash exists, it will be the wrong version.

[brianmay]

I asked about this on the matrix channel https://matrix.to/#/!RRerllqmbATpmbJgCn:nixos.org/$HxXrDb80i36hBG3uY4kE8PaX_G3NsM4bKFInux3Q-Xg?via=nixos.org&via=matrix.org&via=tchncs.de

Probably need to find a better forum where the maintainers of the elxir and npm code can see it.