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: 
Yes. In the new Disney canon novel "Heir to the Jedi", Luke uses his lightsaber in a tunnel as a light source after some creature ate Luke's lamp.

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> “Stay back!” I warned Drusil as I heard the creature choke and spit up the lamp. It wasn’t working anymore—maybe it was simply in the off position rather than broken, but I wasn’t about to search in the dark for it in the bottom of a sewer with something hungry nearby. **We needed to see, so I pulled my lightsaber from my belt and hoped it would give off enough ambient light to spot the creature before it attacked again**. Holding it in front of me in a defensive stance, I turned it on as I heard the creature snarl and thrash in the filth. The blue plasma blade bloomed up and my eyes, dilated in the darkness, saw the thing open its mouth and bunch its powerful back legs for a spring at my throat.
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In *The Clone Wars: [Weapons Factory](http://starwars.wikia.com/wiki/Weapons_Factory)* (S02E06), Barriss Offee and Ashoka Tano use their sabers to provide light when they are trapped beneath some rubble.

![Barriss & Ashoka](https://i.stack.imgur.com/XYTq8.jpg)

In the following episode, *[Legacy of Terror](http://starwars.wikia.com/wiki/Legacy_of_Terror)* (S02E07), Obi-Wan and Anakin use theirs to provide light as they descend into a temple. 

![Obi-Wan & Anakin](https://i.stack.imgur.com/cffqH.jpg)

![Obi-Wan & Anakin](https://i.stack.imgur.com/8u7Tc.jpg)