Light fixture
Water at a light fixture is an electrical problem until it is not.
A drip at a pot light or a flush fixture means water has already reached a box. Stay away from the switch if the plate is wet. Finding the pipe comes after people are clear of shock risk.
Leave the wet switch alone.
Do not keep flipping the light to see the drip. If the cover is wet, stay back and call. 911 belongs in the picture if anyone is at risk.
Kill power at a dry breaker if you can.
A labelled suite panel that is dry can isolate the fixture. Do not reach into a wet panel.
Then treat it as a ceiling leak.
The fixture is where water found an opening, not proof of the source. The suite above, a roof, or a pipe run may all be involved.
Questions people ask
Should I remove the fixture to see the leak?
No. Opening a live, wet box is dangerous and destroys the only evidence of how water entered.
Can the building just replace the light?
Replacing the fixture without naming the water leaves the next box to fail.