AC compressor leak?

[jlodge]

I've been watching a small yellow/greenish leak from the AC compressor since I bought my car in the spring. Initially the leak was very small and intermittent, but yesterday I noticed quite a bit more accumulation (see photo).

A/C still blows cold, although it occasionally makes an odd whooshing/pulsing sound when starting up. I've noticed this since purchase.

As far as I know, everything is stock, although the PO had the system recharged ~ a year ago.

Couple of questions:
- Is this usually caused by the compressor failing or are there other possible explanations?
- How urgent is it to resolve the issue? I.e. should I do something preventatively or wait until something breaks?
- Is a DIY possible or is this one to leave to the pros? Re: my skill level, I've done all my fluids, cooling system refresh, and suspension refresh but am otherwise learning as I go

Thanks in advance for any guidance and suggestions.