The cardano-db-sync development is primarily based on the Nix infrastructure (https://nixos.org/ ), which enables packaging, CI, development environments and deployments.
On how to set up Nix for cardano-db-sync development, please see Building Cardano Node with nix.
We maintain a CODEOWNERS file which provides information who should review a contributing PR. Note that you might need to get approvals from all code owners (even though GitHub doesn't give a way to enforce it).
Fourmolu is our formatter of choice, version 0.10.1.0. We have a script scripts/fourmolize.sh that can be run once fourmolu is installed locally.
Updating package dependencies from Hackage should work like normal in a Haskell project. The most important thing to note is that we pin the index-state of the Hackage package index in cabal.project. This means that cabal will always see Hackage “as if” it was that time, ensuring reproducibility. But it also means that if you need a package version that was released after that time, you need to bump the index-state (and to run cabal update locally).
Because of how we use Nix to manage our Haskell build, whenever you do this you will also need to pull in the Nix equivalent of the newer index-state. You can do this by running nix flake lock --update-input hackageNix.
Many Cardano packages are not on Hackage and are instead in the Cardano Haskell Package repository (CHaP), see the README for (lots) more information. Getting new packages from there works much like getting them from Hackage. The differences are that it has an independent index-state, and that there is a different Nix command you need to run afterwards: nix flake lock --update-input CHaP.
Sometimes we need to use an unreleased version of one of our dependencies, either to fix an issue in a package that is not under our control, or to experiment with a pre-release version of one of our own packages. You can use a source-repository-package stanza to pull in the unreleased version. Try only to do this for a short time, as it does not play very well with tooling, and will interfere with the ability to release cardano-db-sync itself.
For packages that we do not control, we can end up in a situation where we have a fork that looks like it will be long-lived or permanent (e.g. the maintainer is unresponsive, or the change has been merged but not released). In that case, release a patched version to the Cardano Haskell Package repository, which allows us to remove the source-repository-package stanza. See the README for instructions.