There's a reasonably good breakdown of the primary sources, and even some of the scholarly debates over them, in Great Lives from History: The Middle Ages, Vol. 1 (2005).

The main difficulty when discussing them, I think, is that none of them are narrative--no biographies, no city chronicles, no friends telling stories about him in letters. Instead, it's all court and financial records. Scholars have pieced together a provisional, speculative biography from these individual moments. Kind of like how we form a constellation from a few scattered stars.

So, per the Great Lives article:

• We have no sources for his birth and childhood. His birth year is an estimate based on the lives of similar patrician-class artisans (this is fairly common for medievalists to do); any other information comes from what we know about his extended family.
• For the post-Mainz time in Strasbourg, when Gutenberg was presumably metalworking and experimenting with print, most of the sources are lawsuit records. In some cases, these records even get down to the level of preserving witness testimony, but only related to the specific case and not even always to Gutenberg himself.
• For the early, pre-Gutenberg Bible time in Mainz, most attention focuses on the "Helmasperger Document," which is an oath by Johann Fust that is, you guessed it, part of a lawsuit
• Extrapolations about consequences (mostly financial) of Gutenberg losing the aforementioned lawsuit and having to pay Fust a lot of money
• A lot of work can be done with the typeface, ink, and paper of books known to be printed by Gutenberg to demonstrate changing financial or work circumstances
• There are a handful of miscellaneous civic records, like Gutenberg being awarded a pension "whose privileges included an annual allowance for a suit of clothes, allotments of [grain] and wine, and exemption from taxes"

I hope this account has been helpful, even though it's disappointing not to be able to point you to some chronicle or other that was digitized in 2015.