Jaeger with ES: would modifying the shards/replica impact the new indices?

[aujjwal-smarsh]

Hi folks,

I am using Jaeger v2 with Elasticsearch as the storage backend.
This is how I have configured the storage:

      jaeger_storage:
        backends:
          some_storage:
            elasticsearch:
              server_urls:
                - http://elasticsearch:9200
              indices:
                spans:
                  shards: 3
                  replicas: 1
                services:
                  shards: 3
                  replicas: 1
              create_mappings: true     # Create index templates and mappings for Jaeger indices
              log_level: debug
              use_aliases: true
              use_ilm: true

As mentioned here, the shards and replicas are configured at startup. Also, the create_mappings generates the mappings on the index templates.

My doubt was: If I change the shards count to 5 and the replicas count to 2 and restart the Jaeger deployment, would the Jaeger collector make the changes on the index template? Or it would still remain the count set during the first time.

[dosubot[bot]]

If you change the shards and replicas in your Jaeger Elasticsearch config and restart Jaeger, the new settings will only affect new indices created after the change—existing indices will keep their original shard/replica counts. However, since you have both create_mappings: true and use_ilm: true, be aware that Jaeger expects index templates to be managed by the ILM initializer, not by Jaeger itself. In this setup, you should update the index template via the ILM initializer (the es-rollover app) for your new shard/replica settings to take effect on future indices. If both options are enabled, Jaeger will actually return an error and not update the templates itself. See the relevant documentation and code for more details:
Jaeger Elasticsearch storage docs
Jaeger ES config code

To reply, just mention @dosu.

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[aujjwal-smarsh]

@dosu as per the documentation mentioned here

After the initialization, deploy Jaeger with use_ilm: true and use_aliases: true.

It is suggested to enable both the flags for ILM.

[dosubot[bot]]

That's correct—the docs recommend enabling both use_ilm: true and use_aliases: true for ILM. When you do this, Jaeger delegates all index template management (including shard/replica settings) to the ILM initializer (the es-rollover app), not to Jaeger itself. If you want to change the number of shards or replicas, you need to update the es-rollover app's config and re-run its initialization process. Jaeger will not update these settings on its own when use_ilm is enabled, and it will error if you try to enable both use_ilm and create_mappings at the same time—this separation is enforced in the code to avoid conflicts. See the relevant code logic here and here.

To reply, just mention @dosu.

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