Bisecting - Revision history

SamEstep: Make grammar more consistent

2026-05-14T00:55:19Z

Make grammar more consistent

← Older revision		Revision as of 00:55, 14 May 2026
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	* [https://github.com/blitz/hydrasect <code>hydrasect</code>]: select cached commits cached by Hydra		* [https://github.com/blitz/hydrasect <code>hydrasect</code>]: select cached commits cached by Hydra
	* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>]: reduce number of derivations to be built.		* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>]: reduce number of derivations to be built.
	* [https://github.com/samestep/npc <code>npc</code>]: ~~bisects~~ Nixpkgs as a flake input (see below), only considering historical channel bumps instead of all <code>master</code> commits.		* [https://github.com/samestep/npc <code>npc</code>]: bisect Nixpkgs as a flake input (see below), only considering historical channel bumps instead of all <code>master</code> commits.

	== Automating bisects ==		== Automating bisects ==

SamEstep: Move npc link to a more sensible location

2026-05-14T00:54:48Z

Move npc link to a more sensible location

← Older revision		Revision as of 00:54, 14 May 2026
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	* [https://github.com/blitz/hydrasect <code>hydrasect</code>]: select cached commits cached by Hydra		* [https://github.com/blitz/hydrasect <code>hydrasect</code>]: select cached commits cached by Hydra
	* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>]: reduce number of derivations to be built.		* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>]: reduce number of derivations to be built.
			* [https://github.com/samestep/npc <code>npc</code>]: bisects Nixpkgs as a flake input (see below), only considering historical channel bumps instead of all <code>master</code> commits.

	== Automating bisects ==		== Automating bisects ==
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	* [https://git-scm.com/docs/git-bisect#_bisect_run <code>git bisect run</code>]: runs the selected command until the culprit is found.		* [https://git-scm.com/docs/git-bisect#_bisect_run <code>git bisect run</code>]: runs the selected command until the culprit is found.
	* [https://github.com/timokau/nix-bisect <code>nix-bisect</code>]: helps better judge outcome (<code>git bisect</code>'s <code>good</code> vs <code>bad</code> <code>skip</code>) and gives nicer outputs than <code>git bisect run</code>.		* [https://github.com/timokau/nix-bisect <code>nix-bisect</code>]: helps better judge outcome (<code>git bisect</code>'s <code>good</code> vs <code>bad</code> <code>skip</code>) and gives nicer outputs than <code>git bisect run</code>.
	* [https://github.com/samestep/npc <code>npc</code>]: bisects Nixpkgs as a flake input (see below), only considering historical channel bumps instead of all <code>master</code> commits.

	=== Bisecting dependencies ===		=== Bisecting dependencies ===

SamEstep: Mention npc

2026-05-14T00:45:24Z

Mention npc

← Older revision		Revision as of 00:45, 14 May 2026
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	* [https://git-scm.com/docs/git-bisect#_bisect_run <code>git bisect run</code>]: runs the selected command until the culprit is found.		* [https://git-scm.com/docs/git-bisect#_bisect_run <code>git bisect run</code>]: runs the selected command until the culprit is found.
	* [https://github.com/timokau/nix-bisect <code>nix-bisect</code>]: helps better judge outcome (<code>git bisect</code>'s <code>good</code> vs <code>bad</code> <code>skip</code>) and gives nicer outputs than <code>git bisect run</code>.		* [https://github.com/timokau/nix-bisect <code>nix-bisect</code>]: helps better judge outcome (<code>git bisect</code>'s <code>good</code> vs <code>bad</code> <code>skip</code>) and gives nicer outputs than <code>git bisect run</code>.
			* [https://github.com/samestep/npc <code>npc</code>]: bisects Nixpkgs as a flake input (see below), only considering historical channel bumps instead of all <code>master</code> commits.

	=== Bisecting dependencies ===		=== Bisecting dependencies ===

Kiara: remove 'nix-build only' caveat, given the underlying reality of just appending `--dry-run` works just as well with e.g. flake-based commands, making the caveat itself less bad on top of the phrasing here being more of a misnomer

2025-08-20T10:31:46Z

remove 'nix-build only' caveat, given the underlying reality of just appending `--dry-run` works just as well with e.g. flake-based commands, making the caveat itself less bad on top of the phrasing here being more of a misnomer

← Older revision		Revision as of 10:31, 20 August 2025
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	* <code>git bisect start</code> flag [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>]: select merge commits, which depending on the repository can help for caching as well as commit stability.		* <code>git bisect start</code> flag [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>]: select merge commits, which depending on the repository can help for caching as well as commit stability.
	* [https://github.com/blitz/hydrasect <code>hydrasect</code>]: select cached commits cached by Hydra		* [https://github.com/blitz/hydrasect <code>hydrasect</code>]: select cached commits cached by Hydra
	* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>] ~~(<code>nix-build</code> only)~~: reduce number of derivations to be built.		* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>]: reduce number of derivations to be built.

	== Automating bisects ==		== Automating bisects ==

Kiara: update hydrasect to fork unbreaking it

2025-08-19T13:19:15Z

update hydrasect to fork unbreaking it

← Older revision		Revision as of 13:19, 19 August 2025
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	* <code>git bisect start</code> flag [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>]: select merge commits, which depending on the repository can help for caching as well as commit stability.		* <code>git bisect start</code> flag [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>]: select merge commits, which depending on the repository can help for caching as well as commit stability.
	* ~~<s>~~[https://~~git~~.~~qyliss.net~~/hydrasect~~/about/~~ <code>hydrasect</code>]: select cached commits cached by Hydra~~</s> - [https://github.com/NixOS/nixpkgs/issues/323985#issuecomment-2210893775 broken]~~		* [https://github.com/blitz/hydrasect <code>hydrasect</code>]: select cached commits cached by Hydra
	* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>] (<code>nix-build</code> only): reduce number of derivations to be built.		* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>] (<code>nix-build</code> only): reduce number of derivations to be built.

Kiara: bisecting dependencies: non-nixos-configs

2025-01-10T16:48:44Z

bisecting dependencies: non-nixos-configs

← Older revision		Revision as of 16:48, 10 January 2025
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	* [https://github.com/timokau/nix-bisect <code>nix-bisect</code>]: helps better judge outcome (<code>git bisect</code>'s <code>good</code> vs <code>bad</code> <code>skip</code>) and gives nicer outputs than <code>git bisect run</code>.		* [https://github.com/timokau/nix-bisect <code>nix-bisect</code>]: helps better judge outcome (<code>git bisect</code>'s <code>good</code> vs <code>bad</code> <code>skip</code>) and gives nicer outputs than <code>git bisect run</code>.

	== ~~Flakes~~ ==		=== Bisecting dependencies ===

	~~Bisecting~~ changes in a ~~[[flake]]~~ itself can ~~just follow~~ the regular bisecting ~~process.~~		While for regressions from changes in a Nix project itself we can bisect following the regular process, bisecting regression in dependencies is a bit different in the sense the repository you would build is separate from the repository you are bisecting.
	~~Bisecting regressions~~ in ~~flakes' inputs~~ is a bit different in the sense the ~~repositories~~ you ~~are building~~ is ~~not~~ the repository you are bisecting. In this ~~case you can use:~~		One can do this by running a bisect from a local checkout of the dependency that induced the regression.

	* <code>--override-input</code>~~: nix flag~~ that ~~enables bisecting flakes~~' ~~inputs~~		==== Bisecting inputs of [[Flakes\|Flake]] projects ====
	* <code>--flake</code> flag on [[nixos-rebuild]]~~: allows overriding~~ flake directory ~~so you can use nix flake operations from e.g~~. <code>git bisect run</code>
			For dependencies managed using Flakes, such a <code>bisect run</code> can be used with Nix Flake commands' flag <code>--override-input</code> to override specific inputs to use the bisected dependency in its inputs.

			Using <code>git bisect run</code> from your local checkout of the dependency that caused the regression, the flake directory to run a command for can be overridden for a NixOS configuration, for example, using [[nixos-rebuild]]'s <code>--flake</code> flag. If we can reproduce the issue using a <code>dry-build</code>, this might then look like: <code>git bisect run nixos-rebuild dry-build --override-input $DEPENDENCY_NAME $(pwd) --flake <NIXOS_CONFIG_DIR>#<FLAKE_ATTRIBUTE></code>.

			For a regular Nix Flake project, we do not have a command flag like [[nixos-rebuild]]'s <code>--flake</code> to specify the directory of your project. We might then address this by wrapping the Nix command in a script changing directory there, for example using: <code>git bisect run sh -c "cd <PROJECT_DIR>; nix flake check --override-input <DEPENDENCY_NAME> $(pwd)"</code>.

	[[Category:Version control]]		[[Category:Version control]]

Kiara: correct --flake as applying specifically to nixos-rebuild

2025-01-10T13:34:45Z

correct --flake as applying specifically to nixos-rebuild

← Older revision		Revision as of 13:34, 10 January 2025
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	* <code>--override-input</code>: nix flag that enables bisecting flakes' inputs		* <code>--override-input</code>: nix flag that enables bisecting flakes' inputs
	* <code>--flake</code> flag on ~~nix operations~~: allows overriding flake directory so you can use nix flake operations from e.g. <code>git bisect run</code>		* <code>--flake</code> flag on [[nixos-rebuild]]: allows overriding flake directory so you can use nix flake operations from e.g. <code>git bisect run</code>

	[[Category:Version control]]		[[Category:Version control]]

Kiara: add note on hydrasect being broken

2024-07-05T19:20:33Z

add note on hydrasect being broken

← Older revision		Revision as of 19:20, 5 July 2024
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	* <code>git bisect start</code> flag [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>]: select merge commits, which depending on the repository can help for caching as well as commit stability.		* <code>git bisect start</code> flag [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>]: select merge commits, which depending on the repository can help for caching as well as commit stability.
	* [https://git.qyliss.net/hydrasect/about/ <code>hydrasect</code>]: select cached commits cached by Hydra~~, useful for bisecting nixpkgs. After each checkout run~~ <~~code~~>~~git checkout $(hydrasect~~-~~search \| head -1)<~~/~~code>~~.		* <s>[https://git.qyliss.net/hydrasect/about/ <code>hydrasect</code>]: select cached commits cached by Hydra</s> - [https://github.com/NixOS/nixpkgs/issues/323985#issuecomment-2210893775 broken]
	* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>] (<code>nix-build</code> only): reduce number of derivations to be built.		* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>] (<code>nix-build</code> only): reduce number of derivations to be built.

Kiara: better factor bisecting tips

2024-07-02T14:22:34Z

better factor bisecting tips

← Older revision		Revision as of 14:22, 2 July 2024
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	[https://git-scm.com/docs/git-bisect Bisecting] is a feature of version control systems such as [[Git]] and [[Mercurial]] to easily pinpoint regressions. Owing to their reproducibility, Nix and NixOS are well-suited to this. As a result, ~~there are~~ a few ~~common use-cases~~ for Nix.		[https://git-scm.com/docs/git-bisect Bisecting] is a feature of version control systems such as [[Git]] and [[Mercurial]] to easily pinpoint regressions. Owing to their reproducibility, Nix and NixOS are well-suited to this. As a result, we will list a few tips for using tools like this in the Nix context.

	== ~~nixpkgs~~ ==		== Commit selection ==

	~~either~~:		There are different ways to tweak <code>git bisect</code>'s commit selection to reduce the required builds:

	* ~~directly bisect, say from the root of the nixpkgs repository run~~ <code>git bisect start ~~--first-parent master nixos-24.05 && git bisect run nix build -f . lolcat~~</code> ~~if package <code>lolcat</code> broke since <code>nixos-24.05</code>. This uses [https://git-scm.com/docs/git-bisect#_bisect_run git bisect run] to run the test until the culprit is found, while the~~ [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>] ~~flag selects~~ merge commits, which ~~in nixpkgs should be cached in Hydra~~.		* <code>git bisect start</code> flag [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>]: select merge commits, which depending on the repository can help for caching as well as commit stability.
	* [https://~~github~~.~~com~~/~~timokau~~/~~nix-bisect nix-bisect]: in automated bisects handle picking <code>bisect bad</code>~~ / <code>~~bisect skip~~</code> ~~and give nicer outputs~~		* [https://git.qyliss.net/hydrasect/about/ <code>hydrasect</code>]: select cached commits cached by Hydra, useful for bisecting nixpkgs. After each checkout run <code>git checkout $(hydrasect-search \| head -1)</code>.
	* [https://git.qyliss.net/hydrasect/about/ hydrasect]: ~~prioritize hydra-~~cached commits, nixpkgs ~~only~~. After each checkout run <code>git checkout $(hydrasect-search \| head -1)</code>.		* [https://github.com/symphorien/nixpkgs-staging-bisecter <code>nixpkgs-staging-bisecter</code>] (<code>nix-build</code> only): reduce number of derivations to be built.
	* [https://github.com/symphorien/nixpkgs-staging-bisecter nixpkgs-staging-bisecter]: reduce number of derivations to be built, <code>nix-~~build~~</code> ~~only~~.
			== Automating bisects ==

			* [https://git-scm.com/docs/git-bisect#_bisect_run <code>git bisect run</code>]: runs the selected command until the culprit is found.
			* [https://github.com/timokau/nix-bisect <code>nix-bisect</code>]: helps better judge outcome (<code>git bisect</code>'s <code>good</code> vs <code>bad</code> <code>skip</code>) and gives nicer outputs than <code>git bisect run</code>.

	== Flakes ==		== Flakes ==

	Bisecting changes in a flake itself can just follow the regular bisecting process.		Bisecting changes in a [[flake]] itself can just follow the regular bisecting process.
	Bisecting regressions in ~~[[flake]]s~~' inputs ~~typically involves updating~~ the ~~dependency's~~ <code>~~rev~~</code> ~~and~~ <code>~~narHash~~</code> ~~in the <code>~~flake.~~lock</code> file~~. ~~Using tools like~~ <code>~~nix flake prefetch</code>, <code>jq~~</code> ~~and <code>sed</code>, this process [https://gist.github.com/KiaraGrouwstra/70bf11002032b3c265512f4e17607631#file-bisect-sh can be scripted].~~		Bisecting regressions in flakes' inputs is a bit different in the sense the repositories you are building is not the repository you are bisecting. In this case you can use:

			* <code>--override-input</code>: nix flag that enables bisecting flakes' inputs
			* <code>--flake</code> flag on nix operations: allows overriding flake directory so you can use nix flake operations from e.g. <code>git bisect run</code>

	[[Category:Version control]]		[[Category:Version control]]

Kiara: /* nixpkgs */ - reword bisect tools

2024-07-02T09:16:24Z

nixpkgs: - reword bisect tools

← Older revision		Revision as of 09:16, 2 July 2024
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	* directly bisect, say from the root of the nixpkgs repository run <code>git bisect start --first-parent master nixos-24.05 && git bisect run nix build -f . lolcat</code> if package <code>lolcat</code> broke since <code>nixos-24.05</code>. This uses [https://git-scm.com/docs/git-bisect#_bisect_run git bisect run] to run the test until the culprit is found, while the [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>] flag selects merge commits, which in nixpkgs should be cached in Hydra.		* directly bisect, say from the root of the nixpkgs repository run <code>git bisect start --first-parent master nixos-24.05 && git bisect run nix build -f . lolcat</code> if package <code>lolcat</code> broke since <code>nixos-24.05</code>. This uses [https://git-scm.com/docs/git-bisect#_bisect_run git bisect run] to run the test until the culprit is found, while the [https://git-scm.com/docs/git-bisect#Documentation/git-bisect.txt---first-parent <code>--first-parent</code>] flag selects merge commits, which in nixpkgs should be cached in Hydra.
	* [https://github.com/timokau/nix-bisect nix-bisect]: ~~smartly pick~~ <code>bisect bad/skip</code> ~~in automated bisects~~ and give nicer outputs		* [https://github.com/timokau/nix-bisect nix-bisect]: in automated bisects handle picking <code>bisect bad</code> / <code>bisect skip</code> and give nicer outputs
	* [https://git.qyliss.net/hydrasect/about/ hydrasect]: prioritize cached commits in nixpkgs ~~bisects - unfortunately still lacks nix package/flake~~		* [https://git.qyliss.net/hydrasect/about/ hydrasect]: prioritize hydra-cached commits, nixpkgs only. After each checkout run <code>git checkout $(hydrasect-search \| head -1)</code>.
	** after each checkout run <code>git checkout $(hydrasect-search \| head -1)</code>		* [https://github.com/symphorien/nixpkgs-staging-bisecter nixpkgs-staging-bisecter]: reduce number of derivations to be built, <code>nix-build</code> only.
	* [https://github.com/symphorien/nixpkgs-staging-bisecter nixpkgs-staging-bisecter]: ~~like hydrasect but minimize how many~~ derivations ~~you will~~ build ~~even in staging~~

	== Flakes ==		== Flakes ==