[jrockway]

You can stick a proxy in front of apps that don't have features you need like mTLS, tracing, metrics, etc. to get those. Google "service mesh" to explore that space. But to some extent, I think it's all a bit easier if your apps just do the right thing out of the box. Less moving parts. Better integration testing.

Like medicine, every piece of software you use has effects and side-effects. If the advantage of the effects outweigh the disadvantages of the side-effects, then something is a good deal. But if you can avoid the side-effects entirely, that's best.