Question: Since lightsabers give off a visible glow, I could see a Jedi or a Sith using their lightsaber as a lighting source. They were already used as tools (at least in Episode I) so there are some non-violent uses to a lightsaber. Has any Jedi or Sith used their lightsaber in this manner in canon works?

Answer: 
Obi-Wan does just that in the *Revenge of the Sith* novelisation, right after he is attacked by his clone troops.

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> Some undefinable time later, Obi-Wan felt his head and shoulders breach the surface of the lightless ocean. **He unclipped his lightsaber and raised it over his head. In its blue glow he could see that he had come up in a large grotto;** holding the lightsaber high, he tucked away his rebreather and sidestroked across the current to a rock outcropping that was rugged enough to offer handholds. He pulled himself out of the water.
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Rey also does it in *The Rise of Skywalker*, after falling into some sinking sands.

[![enter image description here](https://i.stack.imgur.com/cnyNkm.png)](https://i.stack.imgur.com/cnyNkm.png)
When Luke is being tested by Yoda at the tree of the Dark Side, he lights his saber as he enters the tunnel. I always assumed it was in order to see by its light.

This is supported by the official novelization as mentioned by [Valorum](https://scifi.stackexchange.com/users/20774/valorum).

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> He held his glowing sword in front of him and noticed an object on the cave floor. Pointing his lightsaber downward, Luke illuminated a black, shiny beetle the size of his hand. In an instant, the thing scurried up the slimy wall to join a cluster of its mates.
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