Boundary will indeed give you a bearer token after authentication to present to take further actions in its API. So you'd authenticate to Boundary, get a bearer token, and use that to make one or more requests to connect to infrastructure or services. That bit is pretty much in line with most clouds, platforms, services, etc.
As for complexity, while Boundary overall is by no means a couple hundred lines, I will simply say that the vast majority of code (nearly the entire API) is related to user and resource management...how users are defined and authenticated, how infrastructure and services are described for access, RBAC, etc. The actual networking code performing the secure proxying is quite minimal because at least for the TCP tunnel it's more or less specifying the acceptable TLS parameters for that session and from there you're mostly in `io.Copy` land... it probably works out to a couple hundred lines :-D
What you're doing in Fly looks super cool and the stuff you're doing on gVisor (including the user-mode Wireguard stuff) is super cool too! Thanks for writing it up. And it sounds like the two solutions are more complementary than competing, so maybe at some point in the future you'll find that Boundary has a niche to fill in your setup as well!
However, once authorized, the actual session uses a TLS stack generated for that individual session to establish a secure tunnel. It's explained at https://www.boundaryproject.io/docs/concepts/security/connec... if you're interested.
As for complexity, while Boundary overall is by no means a couple hundred lines, I will simply say that the vast majority of code (nearly the entire API) is related to user and resource management...how users are defined and authenticated, how infrastructure and services are described for access, RBAC, etc. The actual networking code performing the secure proxying is quite minimal because at least for the TCP tunnel it's more or less specifying the acceptable TLS parameters for that session and from there you're mostly in `io.Copy` land... it probably works out to a couple hundred lines :-D
What you're doing in Fly looks super cool and the stuff you're doing on gVisor (including the user-mode Wireguard stuff) is super cool too! Thanks for writing it up. And it sounds like the two solutions are more complementary than competing, so maybe at some point in the future you'll find that Boundary has a niche to fill in your setup as well!