RediSearch module metrics collection

[nantiferov]

Describe the problem
Hi,

I recently started testing RediSearch module for redis and noticed that there is no support for its metrics collection.

So I found these info commands which shows useful information about module stats:

$ redis-cli -p 36379 info modules
# Modules
module:name=RedisCompat,ver=1,api=1,filters=0,usedby=[],using=[],options=[]
module:name=redisgears_2,ver=20020,api=1,filters=0,usedby=[],using=[],options=[]
module:name=search,ver=21005,api=1,filters=0,usedby=[],using=[ReJSON],options=[handle-io-errors]
module:name=ReJSON,ver=20803,api=1,filters=0,usedby=[search],using=[],options=[handle-io-errors]
module:name=timeseries,ver=11202,api=1,filters=0,usedby=[],using=[],options=[]
module:name=bf,ver=20802,api=1,filters=0,usedby=[],using=[],options=[]

# redisgears_2_UninitialisedBackends
redisgears_2_backend_name:js

# search_version
search_version:2.10.5
search_redis_version:7.4.0 - oss

# search_index
search_number_of_indexes:2

# search_fields_statistics
search_fields_text:Text=5,Sortable=1
search_fields_numeric:Numeric=2,Sortable=1
search_fields_tag:Tag=1

# search_memory
search_used_memory_indexes:7052
search_used_memory_indexes_human:0.006725311279296875
search_total_indexing_time:5.9800000190734863

# search_cursors
search_global_idle:0
search_global_total:0

# search_gc
search_bytes_collected:0
search_total_cycles:0
search_total_ms_run:0

# search_dialect_statistics
search_dialect_1:1
search_dialect_2:0
search_dialect_3:0
search_dialect_4:0

# search_runtime_configurations
search_enableGC:ON
search_minimal_term_prefix:2
search_minimal_stem_length:4
search_maximal_prefix_expansions:200
search_query_timeout_ms:500
search_timeout_policy:return
search_cursor_read_size:1000
search_cursor_max_idle_time:300000
search_max_doc_table_size:1000000
search_max_search_results:10000
search_max_aggregate_results:10000
search_gc_scan_size:100
search_min_phonetic_term_length:3

I'm thinking would be good to add these metrics collection:

• search_version
• search_number_of_indexes
• search_used_memory_indexes
• search_total_indexing_time
• search_global_idle
• search_global_total
• search_bytes_collected
• search_total_cycles
• search_total_ms_run

What version of redis_exporter are you running?
Please run redis_exporter --version if you're not sure what version you're running.

• 0.3x.x
• 1.x.x

Running the exporter

Not relevant, feature request.

Screenshots

Not relevant, feature request.

Additional context

I think I can implement this in a week or so by adding flag named like check-search-module, defaults disabled.

In the future, as next step, should be possible to add per index metrics collection, where FT._list shows available indexes, and FT.info <index> shows quite a lot of useful information about index stats and performance.

[oliver006]

Thanks for checking, I think that makes sense!

Happy to review a PR once you're ready.

[nantiferov]

I think PR is ready for review.
Added new docker image and tests for new feature. Looks like working fine to me.

Tested it manually too.