Redis instrumentor doesn't correctly build span metadata for cluster pipelines in redis > 6.x

[gabrielecerami]

Describe your environment

OS: All
Python version: All
Package version: All
Redis-py version: >= 6.x

What happened?

The redis instrumentor currently builds the span metadata for pipelines starting from the command_stack attribute in the Pipeline and ClusterPipeline objects.
see here

In redis-py 6 the cluster pipeline has been refactored, and although the command_stack attribute has been maintained in the ClusterPipeline object (see here) it is not updated anymore with the commands added to the pipeline. As a result, spans for the cluster pipeline in redis > 6 will always have an empty list of commands.

The commands are now appended to the AbstractStategy class (see here and here) which is inherited by the PipelineStrategy class.

The instrumentation will probably need a different set of functions to handle the cluster pipeline.

Steps to Reproduce

1. Install redis-py > 6.x
2. Enable redis instrumentation
3. Examine traces created

Expected Result

ClusterPipeline span attribute DB_STATEMENT contains at least one command and db.redis.pipeline_length is > 0

Actual Result

For all ClusterPipelines span attribute DB_STATEMENT is empty and db.redis.pipeline_length is 0

Additional context

No response

Would you like to implement a fix?

Yes

Tip

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[rite7sh]

Thanks for the report. I looked into this locally, it seems that the Redis instrumentation builds pipeline span metadata in 'util.py' by
reading from 'command_stack'. With redis-py 6.x, 'ClusterPipeline' still has 'command_stack', but it is no longer updated, so the
instrumentation sees an empty list and produces empty spans.
It looks like the commands are now stored on the pipeline strategy,so cluster pipelines in redis-py 6.x will likely need a different way
to extract commands while keeping the current behavior for older versions.
P.S.. this is just evaluation based on @gabrielecerami 's report.