- Haskell `env` and `shellFor` dev shell environments now organize dependencies the same way as regular builds. In particular, rather than receiving all the different lists of dependencies mashed together as one big list, and then partitioning into Haskell and non-Hakell dependencies, they work from the original many different dependency parameters and don't need to algorithmically partition anything.
This means that if you incorrectly categorize a dependency, e.g. non-Haskell library dependency as a `buildDepends` or run-time Haskell dependency as a `setupDepends`, whereas things would have worked before they may not work now.
- The gcc-snapshot-package has been removed. It's marked as broken for \>2 years and used to point to a fairly old snapshot from the gcc7-branch.
- The nixos-build-vms8 -script now uses the python test-driver.
- The riot-web package now accepts configuration overrides as an attribute set instead of a string. A formerly used JSON configuration can be converted to an attribute set with `builtins.fromJSON`.
The new default configuration also disables automatic guest account registration and analytics to improve privacy. The previous behavior can be restored by setting `config.riot-web.conf = { disable_guests = false; piwik = true; }`.
- Stand-alone usage of `Upower` now requires `services.upower.enable` instead of just installing into [environment.systemPackages](options.html#opt-environment.systemPackages).
- nextcloud has been updated to `v18.0.2`. This means that users from NixOS 19.09 can't upgrade directly since you can only move one version forward and 19.09 uses `v16.0.8`.
To provide a safe upgrade-path and to circumvent similar issues in the future, the following measures were taken:
- The pkgs.nextcloud-attribute has been removed and replaced with versioned attributes (currently pkgs.nextcloud17 and pkgs.nextcloud18). With this change major-releases can be backported without breaking stuff and to make upgrade-paths easier.
- Existing setups will be detected using [system.stateVersion](options.html#opt-system.stateVersion): by default, nextcloud17 will be used, but will raise a warning which notes that after that deploy it's recommended to update to the latest stable version (nextcloud18) by declaring the newly introduced setting [services.nextcloud.package](options.html#opt-services.nextcloud.package).
- Users with an overlay (e.g. to use nextcloud at version `v18` on `19.09`) will get an evaluation error by default. This is done to ensure that our [package](options.html#opt-services.nextcloud.package)-option doesn't select an older version by accident. It's recommended to use pkgs.nextcloud18 or to set [package](options.html#opt-services.nextcloud.package) to pkgs.nextcloud explicitly.
::: {.warning}
Please note that if you're coming from `19.03` or older, you have to manually upgrade to `19.09` first to upgrade your server to Nextcloud v16.
:::
- Hydra has gained a massive performance improvement due to [some database schema changes](https://github.com/NixOS/hydra/pull/710) by adding several IDs and better indexing. However, it's necessary to upgrade Hydra in multiple steps:
- At first, an older version of Hydra needs to be deployed which adds those (nullable) columns. When having set [stateVersion ](options.html#opt-system.stateVersion) to a value older than `20.03`, this package will be selected by default from the module when upgrading. Otherwise, the package can be deployed using the following config:
```nix
{ pkgs, ... }: {
services.hydra.package = pkgs.hydra-migration;
}
```
- Automatically fill the newly added ID columns on the server by running the following command:
```ShellSession
$ hydra-backfill-ids
```
::: {.warning}
Please note that this process can take a while depending on your database-size!
:::
- Deploy a newer version of Hydra to activate the DB optimizations. This can be done by using hydra-unstable. This package already includes [flake-support](https://github.com/nixos/rfcs/pull/49) and is therefore compiled against pkgs.nixFlakes.