fix: safely handle concurrent DNS-01 challenges in Present and Cleanup#166
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fix: safely handle concurrent DNS-01 challenges in Present and Cleanup#166
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added 3 commits
February 24, 2026 13:23
… selection Added scenarios for: - Idempotency and record appending during challenges - Proper propagation of TTL configuration - Service Account vs. Auth Token authentication selection - Failure handling during RRSet creation and updates - Robustness against empty record sets
by adding checks whether the challenge key is already existing in the recordset and if not, appending it to it
- delete RRSet if challengeKey is the only record, or there are no records - remove the record if theres more records - do nothing if challengeKey is not existing in the RRSet
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Problem:
When
cert-managerprocesses multiple DNS-01 challenges concurrently for the same DNS record, the webhook was suffering from race conditions:Present()was completely overwriting existing TXT records instead of appending new challenge keys.CleanUp()was using a sledgehammer approach, deleting the entire RRSet even if other concurrent challenges were still relying on other TXT keys in that set.This caused challenges to fail or get permanently stuck in a
pendingstate.Solution:
Refactored the DNS record management to properly handle multiple TXT values as a list:
Present(): Now fetches the existing RRSet and appends the new challenge key to the array if it is not already present, preserving existing keys.CleanUp(): filters out only the specific challenge key requested bycert-managerand deletes RRSet only if empty.