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Maintainer Workflow
The goal of the @NixOS/haskell
team is to keep the Haskell packages in Nixpkgs up-to-date, while making sure
there are no Haskell-related evaluation errors or build errors that get into
the Nixpkgs master
branch.
We do this by periodically merging an updated set of Haskell packages on the
haskell-updates
branch into the master
branch. Each member of the team
takes a two week period where they are in charge of merging the
haskell-updates
branch into master
. This is the documentation for this
workflow.
The workflow generally proceeds in three main steps:
- create the initial
haskell-updates
PR, and update Stackage and Hackage snapshots - wait for contributors to fix newly broken Haskell packages
- merge
haskell-updates
intomaster
Each of these steps is described in a separate section.
There is a script that automates the workflow for merging the currently open
haskell-updates
PR into master
and opening the next PR. It is described
at the end of this document.
Initial haskell-updates
PR
In this section we create the PR for merging haskell-updates
into master
.
-
Make sure the
haskell-updates
branch is up-to-date withmaster
. -
Update the Stackage Nightly resolver used by Nixpkgs and create a commit:
$ ./maintainers/scripts/haskell/update-stackage.sh --do-commit
-
Update the Hackage package set used by Nixpkgs and create a commit:
$ ./maintainers/scripts/haskell/update-hackage.sh --do-commit
-
Regenerate the Haskell package set used in Nixpkgs and create a commit:
$ ./maintainers/scripts/haskell/regenerate-hackage-packages.sh --do-commit
-
Push these commits to the
haskell-updates
branch of the NixOS/nixpkgs repository. -
Open a PR on Nixpkgs for merging
haskell-updates
intomaster
. The recommended PR title and body text are described in themerge-and-open-pr.sh
section.
Notify Maintainers and Fix Broken Packages
After you've done the previous steps, Hydra will start building the new and updated Haskell packages. You can see the progress Hydra is making at https://hydra.nixos.org/jobset/nixpkgs/haskell-updates. This Hydra jobset is defined in the file release-haskell.nix.
Notify Maintainers
When Hydra finishes building all the updated packages for the haskell-updates
jobset, you should generate a build report to notify maintainers of their
newly broken packages. You can do that with the following commands:
$ ./maintainers/scripts/haskell/hydra-report.hs get-report
$ ./maintainers/scripts/haskell/hydra-report.hs ping-maintainers
The hydra-report.hs ping-maintainers
command generates a Markdown document
that you can paste in a GitHub comment on the PR opened above. This
comment describes which Haskell packages are now failing to build. It also
pings the maintainers so that they know to fix up their packages.
It may be helpful to pipe hydra-report.hs ping-maintainers
into xclip
(XOrg) or wl-copy
(Wayland) in order to post on GitHub.
This build report can be fetched and re-generated for new Hydra evaluations. It may help contributors to try to keep the GitHub comment updated with the most recent build report.
Maintainers should be given at least 7 days to fix up their packages when they
break. If maintainers don't fix up their packages within 7 days, then they
may be marked broken before merging haskell-updates
into master
.
Fix Broken Packages
After getting the build report, you can see which packages and Hydra jobs are
failing to build. The most important jobs are the
maintained
and
mergeable
jobs. These are both defined in
release-haskell.nix
.
mergeable
is a set of the most important Haskell packages, including things
like Pandoc and XMonad. These packages are widely used. We would like to
always keep these building.
maintained
is a set of Haskell packages that have maintainers in Nixpkgs.
We should be proactive in working with maintainers to keep their packages
building.
Steps to fix Haskell packages that are failing to build is out of scope for this document, but it usually requires fixing up dependencies that are now out-of-bounds.
Mark Broken Packages
Packages that do not get fixed can be marked broken with the following commands. First check which packages are broken:
$ ./maintainers/scripts/haskell/hydra-report.hs get-report
$ ./maintainers/scripts/haskell/hydra-report.hs mark-broken-list
This shows a list of packages that reported a build failure on x86_64-linux
on Hydra.
Next, run the following command:
$ ./maintainers/scripts/haskell/mark-broken.sh --do-commit
This first opens up an editor with the broken package list. Some of these packages may have a maintainer in Nixpkgs. If these maintainers have not been given 7 days to fix up their package, then make sure to remove those packages from the list before continuing. After saving and exiting the editor, the following will happen:
-
Packages from the list will be added to
configuration-hackage2nix/broken.yaml
. This is a list of Haskell packages that are known to be broken. -
hackage-packages.nix
will be regenerated. This will mark all Haskell pacakges inconfiguration-hackage2nix/broken.yaml
asbroken
. -
The
configuration-hackage2nix/transitive-broken.yaml
file will be updated. This is a list of Haskell packages that depend on a package inconfiguration-hackage2nix/broken.yaml
orconfiguration-hackage2nix/transitive-broken.yaml
-
hackage-packages.nix
will be regenerated again. This will sethydraPlatforms = none
for all the packages inconfiguration-hackage2nix/transitive-broken.yaml
. This makes sure that Hydra does not try to build any of these packages. -
All updated files will be committed.
Merge haskell-updates
into master
Now it is time to merge the haskell-updates
PR you opened above.
Before doing this, make sure of the following:
-
All Haskell packages that fail to build are correctly marked broken or transitively broken.
-
The
maintained
andmergeable
jobs are passing on Hydra. -
The maintainers for any maintained Haskell packages that are newly broken have been pinged on GitHub and given at least a week to fix their packages. This is especially important for widely-used packages like
cachix
. -
Make sure you first merge the
master
branch intohaskell-updates
. Wait for Hydra to evaluate the newhaskell-updates
jobset. Make sure you only mergehaskell-updates
intomaster
when there are no evaluation errors. -
Due to Hydra having only a small number of Darwin build machines, the
haskell-updates
jobset on Hydra often has many queued Darwin jobs. In order to not have these queued Darwin jobs prevent thehaskell-updates
branch from being merged tomaster
in a timely manner, we have special rules for Darwin jobs.-
It is alright to merge the
haskell-updates
branch tomaster
if there are remaining queued Darwin jobs on Hydra. -
We would like to keep GHC and the
mergeable
job building on Darwin. Do not merge thehaskell-updates
branch tomaster
if GHC is failing to build, or themergeable
job has failing Darwin constituent jobs.If GHC and the
mergeable
job are not failing, but merely queued, it is alright to merge thehaskell-updates
branch tomaster
. -
We do not need to keep the
maintained
job building on Darwin. Ifmaintained
packages are failing on Darwin, it is helpful to mark them as broken on that platform.
-
When you've double-checked these points, go ahead and merge the haskell-updates
PR.
After merging, make sure not to delete the haskell-updates
branch, since it
causes all currently open Haskell-related pull-requests to be automatically closed on GitHub.
Script for Merging haskell-updates
and Opening a New PR
There is a script that automates merging the current haskell-updates
PR and
opening the next one. When you want to merge the currently open
haskell-updates
PR, you can run the script with the following steps:
-
Make sure you have previously authenticated with the
gh
command. The script uses thegh
command to merge the current PR and open a new one. You should only need to do this once.This command can be used to authenticate:
$ gh auth login
This command can be used to confirm that you have already authenticated:
$ gh auth status
-
Make sure you have setup your
~/.cabal/config
file for authentication for uploading the NixOS package versions to Hackage. See the following section for details on how to do this. -
Make sure you have correctly marked packages broken. One of the previous sections explains how to do this.
In short:
$ ./maintainers/scripts/haskell/hydra-report.hs get-report $ ./maintainers/scripts/haskell/hydra-report.hs mark-broken-list $ ./maintainers/scripts/haskell/mark-broken.sh --do-commit
-
Merge
master
intohaskell-updates
and make sure to push to thehaskell-updates
branch. (This can be skipped ifmaster
has recently been merged intohaskell-updates
.) -
Go to https://hydra.nixos.org/jobset/nixpkgs/haskell-updates and force an evaluation of the
haskell-updates
jobset. See one of the following sections for how to do this. Make sure there are no evaluation errors. If there are remaining evaluation errors, fix them before continuing with this merge. -
Run the script to merge
haskell-updates
:$ ./maintainers/scripts/haskell/merge-and-open-pr.sh PR_NUM_OF_CURRENT_HASKELL_UPDATES_PR
Find the PR number easily here
This does the following things:
-
Fetches
origin
, makes sure you currently have thehaskell-updates
branch checked out, and makes sure your currently checked-outhaskell-updates
branch is on the same commit asorigin/haskell-updates
. -
Merges the currently open
haskell-updates
PR. -
Updates the version of Haskell packages in NixOS on Hackage.
-
Updates Stackage and Hackage snapshots. Regenerates the Haskell package set.
-
Pushes the commits updating Stackage and Hackage and opens a new
haskell-updates
PR on Nixpkgs. If you'd like to do this by hand, look in the script for the recommended PR title and body text.
-
Update Hackage Version Information
After merging into master
you can update what Hackage displays as the current
version in NixOS for every individual package. To do this you run
maintainers/scripts/haskell/upload-nixos-package-list-to-hackage.sh
. See the
script for how to provide credentials. Once you have configured credentials,
running this takes only a few seconds.
Additional Info
Here are some additional tips that didn't fit in above.
-
Hydra tries to evaluate the
haskell-updates
branch (in thenixpkgs:haskell-updates
jobset) every 4 hours. It is possible to force a new Hydra evaluation without waiting 4 hours by the following steps:- Log into Hydra with your GitHub or Google account.
- Go to the nixpkgs:haskell-updates jobset.
- Click the
Actions
button. - Select
Evaluate this jobset
. - If you refresh the page, there should be a new
Evaluation running since:
line. - Evaluations take about 10 minutes to finish.
-
It is sometimes helpful to update the version of
cabal2nix
/hackage2nix
that our maintainer scripts use. This can be done with themaintainers/scripts/haskell/update-cabal2nix-unstable.sh
script.You might want to do this if a user contributes a fix to
cabal2nix
that will immediately fix a Haskell package in Nixpkgs. First, merge in the PR tocabal2nix
, then runupdate-cabal2nix-upstable.sh
. Finally, runregenerate-hackage-packages.sh
to regenerate the Hackage package set with the updated version ofhackage2nix
. -
Make sure never to update the Hackage package hashes in
pkgs/data/misc/hackage/
, or the pinned Stackage Nightly versions on the release branches (likerelease-21.05
).This means that the
update-hackage.sh
andupdate-stackage.sh
scripts should never be used on the release branches.However, changing other files in
./.
and regenerating the package set is encouraged. This can be done withregenerate-hackage-packages.sh
as described above. -
The Haskell team members generally hang out in the Matrix room #haskell:nixos.org.
-
This is a checklist for things that need to happen when a new member is added to the Nixpkgs Haskell team.
-
Add the person to the @NixOS/haskell team. You may need to ask someone in the NixOS organization to do this, like @domenkozar. This gives the new member access to the GitHub repos like cabal2nix.
-
Add the person as a maintainer for the following packages on Hackage:
-
Add the person to the
haskell
team inmaintainers/team-list.nix
. This team is responsible for some important packages in release-haskell.nix. -
Update the Nextcloud Calendar and work the new member into the
haskell-updates
rotation. -
Optionally, have the new member add themselves to the Haskell section in
CODEOWNERS
. This will cause them to get pinged on most Haskell-related PRs.
-