Introduction

• Supported OpenSearch versions: 1.x, 2.x

OpenSearch maintains API compatibility between versions and remains compatible primarily with Elasticsearch v7.10.2 this version compatibility is automatically retrieved from root/ping endpoint. Based on this version Jaeger uses compatible index mappings and OpenSearch REST API.

OpenSearch does not require initialization other than installing and running OpenSearch . Once it is running, pass the correct configuration values to jaeger.

OpenSearch also has the following officially supported resources available from the community:

• Docker container  for getting a single node up quickly
• Helm chart 
• Kubernetes Operator 

Configuration

Here is example configuration  for OpenSearch.

Shards and Replicas for OpenSearch indices

Shards and replicas are some configuration values to take special attention to, because this is decided upon index creation. This article  goes into more information about choosing how many shards should be chosen for optimization.

Index Rollover

OpenSearch rollover  is an index management strategy that optimizes use of resources allocated to indices. For example, indices that do not contain any data still allocate shards, and conversely, a single index might contain significantly more data than the others. Jaeger by default stores data in daily indices which might not optimally utilize resources. Rollover feature can be enabled by --es.use-aliases=true.

Rollover lets you configure when to roll over to a new index based on one or more of the following criteria:

• max_age - the maximum age of the index. It uses time units : d, h, m.
• max_docs - the maximum documents in the index.
• max_size - the maximum estimated size of primary shards (since Elasticsearch 6.x). It uses byte size units  tb, gb, mb.

Rollover index management strategy is more complex than using the default daily indices and it requires an initialization job to prepare the storage and two cron jobs to manage indices.

To learn more about rollover index management in Jaeger refer to this article .

Initialize

The following command prepares OpenSearch for rollover deployment by creating index aliases, indices, and index templates:

docker run -it --rm --net=host jaegertracing/jaeger-es-rollover:latest init http://localhost:9200 # <1>

If you need to initialize archive storage, add -e ARCHIVE=true.

After the initialization Jaeger can be deployed with --es.use-aliases=true.

Roll over

The next step is to periodically execute the rollover API which rolls the write alias to a new index based on supplied conditions. The command also adds a new index to the read alias to make new data available for search.

docker run -it --rm --net=host -e CONDITIONS='{"max_age": "2d"}' jaegertracing/jaeger-es-rollover:latest rollover  http://localhost:9200 # <1>

<1> The command rolls the alias over to a new index if the age of the current write index is older than 2 days. For more conditions see OpenSearch documentation .

The next step is to remove old indices from read aliases. It means that old data will not be available for search. This imitates the behavior of --es.max-span-age flag used in the default index-per-day deployment. This step could be optional and old indices could be simply removed by index cleaner in the next step.

docker run -it --rm --net=host -e UNIT=days -e UNIT_COUNT=7 jaegertracing/jaeger-es-rollover:latest lookback  http://localhost:9200 # <1>

<1> Removes indices older than 7 days from read alias.

Remove old data

The historical data can be removed with the jaeger-es-index-cleaner that is also used for daily indices.

docker run -it --rm --net=host -e ROLLOVER=true jaegertracing/jaeger-es-index-cleaner:latest 14 http://localhost:9200 # <1>

<1> Remove indices older than 14 days.