auto-index-creation will block app to start when one Mongo cluster node is offline

[yxyeip]

As title, we find an issue if we enable auto-index-creation as true, it will block app to start, if one of Mongo node offline.

The root cause is default value of commitQuorum is "votingMembers": all data-bearing voting replica set members
while one of voting member is down, so this command will never return. It block whole app to start.
We need set it as 1, look like set it as 1, it will also snyc to offline node when it come to online.

While Spring data Mongo didn't prviode function to override this option "commitQuorum".

refer: https://www.mongodb.com/docs/v5.3/reference/command/createIndexes/

[mp911de]

That is likely and blocking the application can also happen on application startup if the MongoDB server isn't available. We generally recommend not using auto-index creation because of operational aspects like these and therefore, the feature is deprecated.

[yxyeip]

Hi @mp911de thanks for your reply, do you have any suggestions for replacement if not use auto index feature?

[mp911de]

Please either use programmatic index creation or create indexes out of band by running scripts against MongoDB via e.g. the shell.

[yxyeip]

Programmatic index creation also need spring data mongodb add support to override commitQuorum option.
Currently, looks like there is no way to override it:

template.indexOps(Person.class)
.ensureIndex(new Index().on("age", Order.DESCENDING).unique()); // we need ensureIndex function has ability to pass CreateIndexOptions obj, then we can override commitQuorum on CreateIndexOptions obj

[mp911de]

We use MongoCollection.createIndex to run the command. Only the createIndexes(…) command provides access to CreateIndexOptions exposing CreateIndexCommitQuorum and maxTimeMS options.

These aren't typically the options Spring Data is working with.

[yxyeip]

DefaultIndexOperations.ensureIndex called createIndexes(keys, indexOptions), my suggestions is provide other method DefaultIndexOperations.ensureIndex will call createIndexes(indexs, createIndexOptions)