[Index Management] Add option to convert to lookup index in the manage index dropdown

[damian-polewski]

Summary

Closes #233996

This PR introduces the core logic and UI for converting an index to a lookup index in Index Management, including a custom React hook, modal enhancements, and integration of the reindex service.

Changes:

• Added an option to convert an index to a lookup index in the manage index dropdown.
• Aligned the ConvertIndexToLookupModal with latest design.
• Added a new useConvertIndexToLookup hook to handle the conversion logic.
• Integrated the reindexService with index_management plugin.
• Updated the fetchIndicesCall to return settings.index.mode of the index.

Demo

Screen.Recording.2025-09-11.at.10.56.16.mov

How to test

1. Create an index that meets requirements (less than 2 billion docs, single shard).

Note

If the index does not meet the requirements, the button will be disabled. For indices that already have a lookup mode, the button will not be visible at all.

2. Navigate to index list and select the created index
3. Select Convert to lookup index option from the Manage index dropdown
4. Change the new lookup index name if needed and press Convert
5. After conversion is done you will be navigated to the lookup index's details page

Checklist

Check the PR satisfies following conditions.

Reviewers should verify this PR satisfies this list as well.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This was checked for breaking HTTP API changes, and any breaking changes have been approved by the breaking-change committee. The release_note:breaking label should be applied in these situations.
• Flaky Test Runner was used on any tests changed
• The PR description includes the appropriate Release Notes section, and the correct release_note:* label is applied per the guidelines
• Review the backport guidelines and apply applicable backport:* labels.

Release Note

Adds an option to convert an index to a lookup index in the manage index dropdown.

[elasticmachine]

Pinging @elastic/kibana-management (Team:Kibana Management)

[damian-polewski]

Hi @elastic/docs I wanted to ask about your opinion on the copy, especially around "Convert to lookup index". I'm wondering if the current version is good from your side or if you would prefer to call this action differently.
Let me know what do you think!

[florent-leborgne]

Some small copy suggestions. Some might not work due to space constraints. Lmk what you think.

Edit: just saw your question, "Convert to lookup index" sounds good to me. I'm wondering if we should highlight somewhere what are the main differences when an index is in lookup mode.

[jovana-andjelkovic]

@damian-polewski lgtm!

[damian-polewski]

Some small copy suggestions. Some might not work due to space constraints. Lmk what you think.

Edit: just saw your question, "Convert to lookup index" sounds good to me. I'm wondering if we should highlight somewhere what are the main differences when an index is in lookup mode.

Hi @florent-leborgne, thank you for the feedback!
Regarding your question about differences when an index is in lookup mode - @jovana-andjelkovic maybe we could link some documentation somewhere so the user can read up on lookup indices?

[florent-leborgne]

Hi! Took a look at the new copy 👀

[mattkime]

Previously, the reindexing service always created a unique pattern for new indices but now anything can be provided. It should make a check using the resolve api to see if the new index name matches an existing index. We should also figure out how we wish to address this in the UI, although we might address it as a follow up task.

[mattkime]

Created this pr to catch attempts to reindex to an existing index - #236011

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 3d9a485
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Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
indexManagement	665	672	+7
upgradeAssistant	181	182	+1
total			+8

Public APIs missing comments

Total count of every public API that lacks a comment. Target amount is 0. Run node scripts/build_api_docs --plugin [yourplugin] --stats comments for more detailed information.

id	before	after	diff
@kbn/index-management-shared-types	149	150	+1
@kbn/upgrade-assistant-pkg-common	10	11	+1
indexManagement	250	253	+3
reindexService	55	54	-1
total			+4

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
indexManagement	688.6KB	695.7KB	+7.0KB
upgradeAssistant	228.7KB	228.1KB	-569.0B
total			+6.5KB

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
indexManagement	31.8KB	32.0KB	+113.0B
reindexService	3.3KB	3.1KB	-216.0B
total			-103.0B

Unknown metric groups

API count

id	before	after	diff
@kbn/index-management-shared-types	149	150	+1
@kbn/upgrade-assistant-pkg-common	10	11	+1
indexManagement	255	258	+3
reindexService	62	61	-1
total			+4

History

• 💚 Build #341969 succeeded f0dd1da
• 💔 Build #341817 failed 58fec71
• 💔 Build #341777 failed 17e7b16
• 💛 Build #341480 was flaky c557dc0
• 💔 Build #341376 failed 9d77bb8
• 💔 Build #340901 failed 52612ab

cc @damian-polewski