The dgraph_active_mutations_total monitoring metric disappears

[gooohgb]

Describe the bug

In certain environments, the dgraph_active_mutations_total monitoring metric disappears. During local debugging, I observed that this key only exists after a write request is triggered. This behavior might be unexpected as the metric disappears suddenly in production without any restarts.

To Reproduce

Steps to reproduce the behavior:

Deploy Dgraph version v24.0.2 in the local environment.
Monitor the dgraph_active_mutations_total metric.
By default, this key does not exist; it appears after a write request.

Expected behavior

The dgraph_active_mutations_total metric always exists.

Screenshots

Environment

• Version [e.g. v24.0.2]