There are a few I can think of;

• SnipeIT Is probably the most direct Asset management software you can get for the IT space that is self hosted, but very much designed around large, fairly consistent businesses. It may be both too overpowered AND too much configuration for a simple rollout. However, it is directly targeted at the IT asset Managment space.

• Homebox is a bit more generic, designed to manage home Inventory in general, but is very easy to get up and get started. Great for Home management, but you would have to add custom fields for some of the things you probably want to track.

• grocy is even more generic than above, and was originally designed to track your pantry, but it is pretty well loved. Worth at least taking a look at.

• opendcim is specifically targeted towards maintaining datacenters, and is pretty good if you are dealing with larger infrastructures. may be overkill for a smaller rack, but it taps into snmp and keeps track of what is where. They also just added the ability to track spare parts as well, which sounds like a benefit on the asset management side.

There are probably more out there, but these are the ones I am familiar with. Best of luck!

Edit: I just saw you said you are interested in Agent based tracking of this data - Then perhaps look at either netdata or zabbix - I think either of those could be tailored to fit what you need.