Metric/mysql innodb mem total

[naman47vyas]

Description:
This PR generated from the context to adding metrics that are not supported by otel itself. The idea being querying the server variables of mysql to create metrics, meanwhile documenting the process of adding a new metric itself.

This PR adds a metric called mysql.innodb.mem_total, indicates the total memory used by the innodb. As of the current state of the PR, the metric is added successfully and the same is reflected by the running mw-agent, however might need some insights in testing as one test (scrape-has-partial-failure) is failing.

Initial investigations reveal that this is due to the discrepancy in the number of actualMetrics(2: mysql.buffer_pool.pages and mysql.innodb.mem_total) and expectedMetrics(1:mysql.buffer_pool.pages). Currently digging in for the reasons for this mismatch.

[naman47vyas]

The commit makes the test-partial-scrape pass. Did this by adding a metric in expected_partial.yaml:

- description: Total memory used by InnoDB, as shown in the BUFFER POOL AND MEMORY section of SHOW ENGINE INNODB STATUS.
            name: mysql.innodb.mem_total
            gauge:
              dataPoints:
                - asInt: "-1"
                  startTimeUnixNano: "1000000"
                  timeUnixNano: "2000000"
            unit: By

This is done on an assumptions:
1.) You want the metric to fail in the scrape-partial test.
2.) You should get the value of mysql.innodb.mem_total as -1 when it fails.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[github-actions]

Closed as inactive. Feel free to reopen if this PR is still being worked on.