[9.5] fix(outlook): retry LDAP user searches with fresh connections (#4441) - #4464
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Part of elastic/sdh-search#1898 ## Problem On large on-prem Exchange deployments the Outlook Server connector enumerates users from Active Directory via LDAP before opening each mailbox over EWS. `ExchangeUsers` kept a single cached `ldap3` connection for both the normal-user and admin-user searches. `get_user_accounts()` consumes users lazily: it yields each normal user, the sync processes that mailbox (often for hours), then continues. The admin-user LDAP search can therefore run days after the first bind. AD or intermediate network gear often drops the idle TCP session, and the next search fails with errors such as: ``` UsersFetchFailed: Something went wrong while fetching users. Error: socket sending error[Errno 104] Connection reset by peer ``` Unlike the Office365 Graph path, LDAP had no retry layer. A single transient failure aborted the entire sync. A customer on SDH #1898 hit this after indexing 4.2M+ documents over ~45 hours. ## Fix - Replace the cached LDAP connection with a fresh `Connection` per search. - Add `_ldap_search()` with the existing `@retryable` settings (`RETRIES`, `RETRY_INTERVAL`, exponential backoff) and `skipped_exceptions=[UsersFetchFailed]` so empty LDAP results are not retried. - Unbind after each search attempt. - Refactor `_fetch_normal_users` / `_fetch_admin_users` to call the shared helper. ## Checklists #### Pre-Review Checklist - [x] this PR does NOT contain credentials of any kind, such as API keys or username/passwords (double check `config.yml.example`) - [x] this PR has a meaningful title - [x] this PR links to all relevant github issues that it fixes or partially addresses - [x] if there is no GH issue, please create it. Each PR should have a link to an issue - [x] this PR has a thorough description - [x] Covered the changes with automated tests - [x] Tested the changes locally - [ ] Added a label for each target release version (example: `v7.13.2`, `v7.14.0`, `v8.0.0`) - [ ] For bugfixes: backport safely to all minor branches still receiving patch releases - [x] Considered corresponding documentation changes - [x] Contributed any configuration settings changes to the configuration reference - [x] if you added or changed Rich Configurable Fields for a Native Connector, you made a corresponding PR in [Kibana](https://github.com/elastic/kibana/blob/main/packages/kbn-search-connectors/types/native_connectors.ts) #### Changes Requiring Extra Attention - [ ] Security-related changes (encryption, TLS, SSRF, etc) - [ ] New external service dependencies added. ## Related Pull Requests * #4406 — skip accounts with non-primary SMTP addresses * #4078 — skip AD users without a valid `mail` attribute * #4094 — per-account EWS error handling and TLS hardening ## Release Note **Outlook Server connector**: LDAP user enumeration now opens a fresh Active Directory connection per search and retries transient network failures instead of aborting long syncs when the admin-user query runs on a stale connection. Made with [Cursor](https://cursor.com) --------- Co-authored-by: Cursor <cursoragent@cursor.com> Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
entsearchmachine
approved these changes
Sep 9, 2026
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Backports the following commits to 9.5: