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feat(deploy): add rollback and switch-generation just recipes #249

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nimmo merged 1 commit from feat/rollback-and-generation-just-recipes into main

2026-09-21 21:22:53 +01:00

nimmo commented

2026-09-21 20:56:21 +01:00

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Summary

Adds two new Just recipes for generation management without rebuilding.

New recipes

`just rollback`

Rolls back to the previous generation without rebooting.

Uses the flake so it works on this flake-based config (sudo nixos-rebuild --flake .#<host> switch --rollback).
Preserves the current Electra specialisation (igpu/dgpu) if one is active.

`just switch-generation <N>`

Switches to an explicit previous generation without rebooting.

Validates that /nix/var/nix/profiles/system-<N>-link exists.
Preserves the current specialisation if one is active.
Sets the system profile and runs switch-to-configuration switch directly.

Validation

nix flake check passes.
The rollback recipe uses the same command pattern that was just proven on Electra in #237.

## Summary Adds two new Just recipes for generation management without rebuilding. ## New recipes ### `just rollback` Rolls back to the previous generation without rebooting. - Uses the flake so it works on this flake-based config (`sudo nixos-rebuild --flake .#<host> switch --rollback`). - Preserves the current Electra specialisation (`igpu`/`dgpu`) if one is active. ### `just switch-generation <N>` Switches to an explicit previous generation without rebooting. - Validates that `/nix/var/nix/profiles/system-<N>-link` exists. - Preserves the current specialisation if one is active. - Sets the system profile and runs `switch-to-configuration switch` directly. ## Validation - `nix flake check` passes. - The rollback recipe uses the same command pattern that was just proven on Electra in #237.

nimmo added 1 commit

2026-09-21 20:56:22 +01:00

feat(deploy): add rollback and switch-generation just recipes

AI pull-request review / review (pull_request) Successful in 1m6s

Details

37910ccba9

nimmo commented

2026-09-21 20:57:30 +01:00

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Automated code review

Reviewed commit: 9dd9c91e54b695f2078945ea92924e59abcd7bc9

Verdict: Ready to merge

No blocking or important findings were retained, and deterministic checks passed. Suggestions remain advisory.

Overall assessment

The PR adds two Just recipes, rollback and switch-generation, to manage NixOS system generations. The rollback recipe correctly handles Electra specialisations by reading /etc/nixos-specialisation and passing the appropriate flag to nixos-rebuild. The switch-generation recipe manually manipulates the system profile and activates a specific generation, including validation for the existence of the target generation link and the specialisation binary. The implementation is robust, handling edge cases like missing specialisation files by defaulting to base.

Blocking findings

None.

Important findings

None.

Suggestions

None.

Tests and validation

No configured deterministic checks.

Questions

Does nixos-rebuild switch --rollback automatically handle the specialisation flag in the same way as the manual implementation, or is the explicit handling necessary for all NixOS versions supported by this flake?

Review limitations

I cannot run just rollback or just switch-generation to verify their behavior on a live system.
I cannot verify the existence of /etc/nixos-specialisation or its contents on the target hosts.
I am assuming the nixos-rebuild and switch-to-configuration commands behave as documented.

Diff coverage

justfiles/deploy.just: reviewed — included in a context-limited batch

Review metadata

Reviewer: forgejo-ai-review v1
Model: qwen3.6:35b-a3b-q8_0
Guidance loaded: .forgejo/ai-review.md, .forgejo/ai-review.yml, AGENTS.md, docs/auto-update-remediation.md, docs/nova-remote-builder.md, README.md
Commits considered: 1
Previous automated review: updated
Findings: 0

## Automated code review Reviewed commit: `9dd9c91e54b695f2078945ea92924e59abcd7bc9` ## Verdict: Ready to merge No blocking or important findings were retained, and deterministic checks passed. Suggestions remain advisory. ### Overall assessment The PR adds two Just recipes, `rollback` and `switch-generation`, to manage NixOS system generations. The `rollback` recipe correctly handles Electra specialisations by reading `/etc/nixos-specialisation` and passing the appropriate flag to `nixos-rebuild`. The `switch-generation` recipe manually manipulates the system profile and activates a specific generation, including validation for the existence of the target generation link and the specialisation binary. The implementation is robust, handling edge cases like missing specialisation files by defaulting to base. ### Blocking findings None. ### Important findings None. ### Suggestions None. ### Tests and validation - No configured deterministic checks. ### Questions - Does `nixos-rebuild switch --rollback` automatically handle the specialisation flag in the same way as the manual implementation, or is the explicit handling necessary for all NixOS versions supported by this flake? ### Review limitations - I cannot run `just rollback` or `just switch-generation` to verify their behavior on a live system. - I cannot verify the existence of `/etc/nixos-specialisation` or its contents on the target hosts. - I am assuming the `nixos-rebuild` and `switch-to-configuration` commands behave as documented. ### Diff coverage - `justfiles/deploy.just`: **reviewed** — included in a context-limited batch <details><summary>Review metadata</summary> - Reviewer: forgejo-ai-review v1 - Model: qwen3.6:35b-a3b-q8_0 - Guidance loaded: .forgejo/ai-review.md, .forgejo/ai-review.yml, AGENTS.md, docs/auto-update-remediation.md, docs/nova-remote-builder.md, README.md - Commits considered: 1 - Previous automated review: updated - Findings: 0 </details>

nimmo force-pushed feat/rollback-and-generation-just-recipes from 37910ccba9

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nimmo force-pushed feat/rollback-and-generation-just-recipes from de36680fe2

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