>Keeping changesets small so that it's easier to debug when something goes wrong? Blown out of the water by deploying everything at once.

The size of your monodeploy is orthoganol to the concept of monodeploy. You can make a large change or a small change.

In fact your deploy can be smart. For a specific service in a full system monodeploy when upgrading from v2 to v3 it can do some sort of diff on the source of a specific service and if there's no difference it goes from v2 -> v3 without a new build and uses the same artifact from v2 to v3. The entire point is though that this service (or the entire system) still goes from v2 to v3 and it tagged this way. This is an optional optimization for speed.

In fact, your compiler when building artifacts ALREADY does this. It caches huge parts of the build and reuses it. A deploy can do the same.

This is the important concept of a monodeploy: The static check; The integration testing. The verification of the ENTIRE system as a whole. Your monodeploy determines what new artifacts need to be recreated, what artifacts need to be reused... verifies everything, and deploys.

>Requiring a monodeployment turns canarying or A/B testing entire classes of changes into a blocking rollout where any other feature work has to move at the pace of the slowest change.

Again orthoganol. Your complaining that a monodeploy is slow. Integration testing and unit testing are also slow and take time. The monodeploy is for safety. If you're saying speed > safety, here's an idea: throw all testing out the window as well. That's a big speed up right there.

If your monodeploy is slow, work on speeding it up. Work on it being smarter and faster. Do you throw testing out the window because it's slow or do you work on speeding it up? Make the smart choice.

>The gold standard is that each version of your service can work with each other version of your service, because in The Real World your service will spend time in those states.

And that gold standard is stupid. We can do better. We can go to a state where different versions between different services don't exist. Only one monoversion. You throw that concept of different versions out the window then you also throw the possibility of a mismatch out the window as well.

You're trying to deal with an error. I'm saying make the error not exist.

>No, because if it's still possible to mix versions in your services, then a monodeploy doesn't actually solve any issues.

It's not possible to mix versions in a monodeploy because the whole concept of it is to have ONE version of everything. Let me be clear I'm talking about a MONOREPO + MONOBUILD + MONODEPLOY. If there's only one version of everything and it's all deployed than issues are solved under this model. At this point I think you just don't like being wrong.

>I actually am a big fan of fewer services and deploying bigger artifacts, but if you have multiple services, you have to act like you have multiple services.

A monodeploy doesn't preclude multiple services. You can still act like it's different services. A monodeploy + monorepo just makes sure there's ONE version of the entire system.

You're solution here is just saying you want to be able to deploy different versions of different services in a staggered way. You want different repos so different modules of the system can move out of step with everything else. Service A is at v23, Service B is at v32.

The only way to deal with this mismatch is to have complicated "versioning" system on top of that where API contracts between services only accept "backward compatible" changes. This works but it's also extra complication and extra restriction. You can no longer radically change an API because it can break a number of systems in different repos. You're stuck. Or if you're willing to deal with the fallout you can make breaking changes and accept the risk whilst under my system the risk doesn't even exist.

You are advocating for an idea that's definitively worse. But you'll never admit it, not right now anyway because basically you've dug your heals into the ground. At this point I've never seen a human who is so unbiased they are capable of proper reasoning to flip their stance. If we continue talking, you will continue to build logical scaffolding to support YOUR point rather then to support A point and it's pointless (punintended) to keep going.

I'm ok to keep going, but I think it's completely obvious to any neutral arbiter that the conversation is over and that your perspective is rationally worse.

What functional programmers get wrong about systems