feat: add ringctl patch revert command structure (!361) · Merge requests · GitLab.com / GitLab Infrastructure Team / ringctl

What does this MR do?

Implements ringctl patch revert command to automate patch reversion during incident response.

Implementation

Command: ringctl patch revert <patch-id> -e <environment> [--dry-run] [--priority N]

Complete revert flow:

Validates patch contains only supported operations (replace) more operations to be implemented later
Finds the commit that applied the patch using GitLab Search API
Extracts old attribute values by reading cell files at parent commit
Creates new revert patch with extracted old values
Deletes the failed patch
Both operations in a single MR with descriptive context

Components added:

cmd/patch_revert.go - Command implementation with operation validation
lib/tissue/client.go - Added FindPatchApplicationCommit(), Instance(), Project(), Git()
lib/gitlab/client_wrapper.go - Added SearchCommits() and Compare() wrappers
lib/patch/revert.go - Added ExtractOldValues(), extractValuesFromCellFile(), CreateRevertOperations()
lib/tissue/templates/patch_mr.md - Enhanced with revert-specific description
lib/tissue/gitlab_cells_storage.go - Improved URL parsing with regex
Tests: lib/patch/revert_test.go, lib/tissue/client_test.go - 9 test cases total

Key Design Decisions

Robust value extraction:

Uses GitLab Search API (single call vs pagination)
Reads actual cell files at parent commit
Parses JSON directly (not regex on diff text)
Handles complex JSON values correctly

Revert patch behavior:

Starts from failed ring (editable in generated MR)
Sets completed_after_ring to failed ring
Priority default: 1 (executes before other patches)
Origin: "revert" for tracking
Creates new unique patch ID

Error handling:

Validates only replace operations supported
Cleanup revert patch if delete fails
Comprehensive error messages with context

Testing

Unit tests (9 test cases):

go test ./lib/patch ./lib/tissue -v
# All tests pass ✓

Coverage:

CreateRevertOperations - Operation creation logic
extractValuesFromCellFile - JSON parsing and extraction
ExtractOldValues - Complete extraction flow with mocked API
FindPatchApplicationCommit - Commit search with mocked Search API

Verified with cellsdev:

ringctl patch revert 01K61PZHDYKD6WBKX7NHQPKH9V -e cellsdev --priority 2

Results:

Created MR: https://ops.gitlab.net/gitlab-com/gl-infra/cells/tissue/-/merge_requests/1151
Revert patch: 01K7P3555EZRZQQJYMN8GF9HB0 (priority 2, starts failed ring)
Deleted patch: 01K61PZHDYKD6WBKX7NHQPKH9V
MR description: "reverts patch X by deleting it and creating..."

Dry-run support:

ringctl patch revert 01K61PZHDYKD6WBKX7NHQPKH9V -e cellsdev --dry-run

Shows complete revert preview without making changes.

Reviewer Feedback Addressed

Robustness improvements:

✅ JSON parsing instead of regex for old value extraction
✅ GitLab Search API instead of commit pagination
✅ Proper parent commit handling via ParentIDs
✅ Transaction cleanup if delete fails

Code quality:

✅ Reduced cognitive complexity by extracting helper functions
✅ Configurable constants (maxPages, commit message format)
✅ Robust URL parsing with regex pattern
✅ Comprehensive error handling

Metadata correctness:

✅ Starts from failed ring (reviewers can adjust in MR if needed)
✅ Sets completed_after_ring to failed ring
✅ Dynamic URL construction using client methods
✅ Enhanced MR template for revert context

Current Scope

Supported operations: Replace operations only (covers 90%+ of patches)

Validation: Fails fast with clear error for unsupported operation types

Future enhancements (separate MRs):

Support add/remove/move/copy operations
Additional edge case handling

Why

Automates the manual reversion process documented in the patching runbook:

~~Manual deletion via ringctl patch delete~~
~~Manual git history inspection for old values~~
~~Manual revert patch creation~~
~~Manual priority calculation~~

Edited Oct 16, 2025 by Maina Ng'ang'a

feat: add ringctl patch revert command structure