PMM-7424 Add dbStatsCollector

[kanakagrawal]

PMM-7424

Add dbStats collector

Here are the metrics added because of this new collector (testdb is name of database I added. Same metrics are added for all databases)

# HELP mongodb_dbstats_testdb_avgObjSize dbstats_testdb.
# TYPE mongodb_dbstats_testdb_avgObjSize untyped
mongodb_dbstats_testdb_avgObjSize{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 40
# HELP mongodb_dbstats_testdb_clusterTime_signature_keyId dbstats_testdb.$clusterTime.signature.
# TYPE mongodb_dbstats_testdb_clusterTime_signature_keyId untyped
mongodb_dbstats_testdb_clusterTime_signature_keyId{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 0
# HELP mongodb_dbstats_testdb_collections dbstats_testdb.
# TYPE mongodb_dbstats_testdb_collections untyped
mongodb_dbstats_testdb_collections{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 3
# HELP mongodb_dbstats_testdb_configServerState_opTime_t dbstats_testdb.$configServerState.opTime.
# TYPE mongodb_dbstats_testdb_configServerState_opTime_t untyped
mongodb_dbstats_testdb_configServerState_opTime_t{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 1
# HELP mongodb_dbstats_testdb_dataSize dbstats_testdb.
# TYPE mongodb_dbstats_testdb_dataSize untyped
mongodb_dbstats_testdb_dataSize{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 1200
# HELP mongodb_dbstats_testdb_fsTotalSize dbstats_testdb.
# TYPE mongodb_dbstats_testdb_fsTotalSize untyped
mongodb_dbstats_testdb_fsTotalSize{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 9.82899539968e+11
# HELP mongodb_dbstats_testdb_fsUsedSize dbstats_testdb.
# TYPE mongodb_dbstats_testdb_fsUsedSize untyped
mongodb_dbstats_testdb_fsUsedSize{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 1.31967700992e+11
# HELP mongodb_dbstats_testdb_indexSize dbstats_testdb.
# TYPE mongodb_dbstats_testdb_indexSize untyped
mongodb_dbstats_testdb_indexSize{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 49152
# HELP mongodb_dbstats_testdb_indexes dbstats_testdb.
# TYPE mongodb_dbstats_testdb_indexes untyped
mongodb_dbstats_testdb_indexes{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 3
# HELP mongodb_dbstats_testdb_numExtents dbstats_testdb.
# TYPE mongodb_dbstats_testdb_numExtents untyped
mongodb_dbstats_testdb_numExtents{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 0
# HELP mongodb_dbstats_testdb_objects dbstats_testdb.
# TYPE mongodb_dbstats_testdb_objects untyped
mongodb_dbstats_testdb_objects{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 30
# HELP mongodb_dbstats_testdb_ok dbstats_testdb.
# TYPE mongodb_dbstats_testdb_ok untyped
mongodb_dbstats_testdb_ok{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 1
# HELP mongodb_dbstats_testdb_storageSize dbstats_testdb.
# TYPE mongodb_dbstats_testdb_storageSize untyped
mongodb_dbstats_testdb_storageSize{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 49152
# HELP mongodb_dbstats_testdb_views dbstats_testdb.
# TYPE mongodb_dbstats_testdb_views untyped
mongodb_dbstats_testdb_views{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 0

---

• Tests passed.
• Fix conflicts with target branch.
• Update jira ticket description if needed.
• Attach screenshots/console output to confirm new behavior to jira ticket, if applicable.

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[it-percona-cla]

All committers have signed the CLA.

[kanakagrawal]

@percona-csalguero can you approve for running workflows on this PR?

[kanakagrawal]

Github Actions has added some linter suggestions in the code. But I've followed the coding style as used at other places in the code. It says -

exporter/dbstats_collector.go:45:3: return with no blank line before (nlreturn)
exporter/dbstats_collector.go:55:4: continue with no blank line before (nlreturn)
Function 'TestDBStatsCollector' is too long (77 > 60) (funlen)
exporter/dbstats_collector_test.go:58:8: ctx, compatibleMode are missing in dbstatsCollector (exhaustivestruct) c := &dbstatsCollector{

At many places in the current code, these scenarios already happens.

For now, I'm ignoring it. Let me know if I should address these linter suggestions.

[percona-csalguero]

Hello again.
This looks good. I ran the tests and they are passing. I just requested a small change just to make the main list more clear and we can filter out metrics.

Thanks

[percona-csalguero]

Can we make the prefix cs + db?
I am thinking about a way to group all the metrics from this collector in the main list.
Thanks,

[kanakagrawal]

I'm confused about what is cs? Do you mean to append just the string like this -

 		prefix := "cs" + db

[percona-csalguero]

some prefix to identify the collector
dbstats_ or something like that.

[kanakagrawal]

I've added the dbstats_ prefix. Here is an example metric after that (testdb is name of database)-

mongodb_dbstats_testdb_indexes{cl_id="611fa5e6165e2964515910a7",cl_role="shardsvr",rs_nm="rs1",rs_state="1"} 3

I've also updated the test case and metrics mentioned in PR description.

[percona-csalguero]

@kanakagrawal thanks for making the requested changes.
I approved the PR but we need a second approval to merge it. While other team members review and approve the PR, feel free to update the Changelog file and add yourself as a contributor.

[kanakagrawal]

@kanakagrawal thanks for making the requested changes.
I approved the PR but we need a second approval to merge it. While other team members review and approve the PR, feel free to update the Changelog file and add yourself as a contributor.

I've updated the Changelog file. I'm not sure what you meant by adding myself as a contributor? I've signed the CLA if that is what you meant.

[kanakagrawal]

@percona-csalguero there is one issue with this PR. Even after setting the d.compatibleMode to true, the old metrics are not added here

		for _, metric := range makeMetrics(prefix, dbStats, d.topologyInfo.baseLabels(), d.compatibleMode) {
			ch <- metric
		}

I see that for mongos old metrics are already added in the mongosMetrics function like this -

# HELP mongodb_mongos_db_data_size_bytes The total size in bytes of the uncompressed data held in this database
# TYPE mongodb_mongos_db_data_size_bytes gauge
mongodb_mongos_db_data_size_bytes{db="admin",shard="rs1"} 599
mongodb_mongos_db_data_size_bytes{db="admin",shard="rs2"} 221
mongodb_mongos_db_data_size_bytes{db="config",shard="rs1"} 130185
mongodb_mongos_db_data_size_bytes{db="config",shard="rs2"} 130152
mongodb_mongos_db_data_size_bytes{db="testdb",shard="rs1"} 1200
mongodb_mongos_db_data_size_bytes{db="testdb",shard="rs2"} 0
# HELP mongodb_mongos_db_index_size_bytes The total size in bytes of all indexes created on this database
# TYPE mongodb_mongos_db_index_size_bytes gauge
mongodb_mongos_db_index_size_bytes{db="admin",shard="rs1"} 36864
mongodb_mongos_db_index_size_bytes{db="admin",shard="rs2"} 16384
mongodb_mongos_db_index_size_bytes{db="config",shard="rs1"} 208896
mongodb_mongos_db_index_size_bytes{db="config",shard="rs2"} 184320
mongodb_mongos_db_index_size_bytes{db="testdb",shard="rs1"} 49152
mongodb_mongos_db_index_size_bytes{db="testdb",shard="rs2"} 0

But they are missing for mongod.

With this patch, database name is part of the metric name. So, we need to modify the metricRenameAndLabel call for these metrics. WDYT?

[denisok]

OK, we are moving it to QA and checking if everything works from QA perspective