5 ms·

> Consul is a service mesh. It’s your dynamic service discovery and routing layer. How does this differ from DNS?

lmm 5y ago
Dynamic-first, better support for failover etc.. It's probably not doing anything that you couldn't build on top of DNS, but it's designed from the ground up for clustered deployments.
anilgulecha 5y ago
Really high level, it doesn't. It's an internal dynamic DNS, essentially.
- zeeZ 5y ago
  One of their primary query interfaces actually even is DNS.
foota 5y ago
I think service discovery is typically related to e.g., request routing in a way that DNS isn't. DNS could probably replace a lot of the ways service discovery is used today, but it would be a very non-typical setup, which is arguably worse than the custom things people use for it today.
withinboredom 5y ago
DNS gets cached all up and down the stack. Your OS, routers, application libraries and probably even your application code might cache it. Consul allows you to have it handle the caching, and be notified when a service goes away so it won’t return that address to your application.
xxs 5y ago
the thing can even provide dns... but it has fancy interfaces and an http endpoint. Technically you could do everything with dns just fine. Even if consul provides some sort of liveness (due to latency and concurrency it means little), I can't think of a usable case where the clients won't have retries and ability to maintain multiple open sockets, etc.
- fragmede 5y ago
  Consul's notion of a service includes port numbers, and while I'm sure you could hack something up using DNS txt records and default port numbers, it's an important distinction because it means multiple instances running on one box can easily be discovered.
nonameiguess 5y ago
I'm not familiar with Consul specifically, but service meshes I am familiar with give you a lot more than just mapping of service names to dynamic IPs. They bundle things like TLS termination, reverse proxying, network policy enforcement, automatic certificate provisioning and key rotation, firewalls potentially aware of anything from layer 3 to layer 7. Where I think companies are going about this wrong sometimes is thinking having their networks be software-defined and handled by some all-in-one product suite means they no longer need network engineers and can they just rely entirely on application developers who specialize in general programming and fall back to vendor support contracts if anything gets too confusing. Admittedly, there's some self interest speaking there, because I work as a consulting engineer for one of these vendors where we go way beyond "support" to embed full time in external product teams with a dependency on our products (though we also offer basic support for companies that think they can get away with it). But to my mind, no software suite can let you get away with not needing any kind of IT ops at all. Smaller companies may assess that the risk is worth it to focus solely on product, but as far as I can tell, Roblox is not a small company (or shouldn't be, given the traffic scale of their platform).

lmm 5y ago

Dynamic-first, better support for failover etc.. It's probably not doing anything that you couldn't build on top of DNS, but it's designed from the ground up for clustered deployments.

anilgulecha 5y ago

Really high level, it doesn't. It's an internal dynamic DNS, essentially.

zeeZ 5y ago
One of their primary query interfaces actually even is DNS.

foota 5y ago

I think service discovery is typically related to e.g., request routing in a way that DNS isn't. DNS could probably replace a lot of the ways service discovery is used today, but it would be a very non-typical setup, which is arguably worse than the custom things people use for it today.

withinboredom 5y ago

DNS gets cached all up and down the stack. Your OS, routers, application libraries and probably even your application code might cache it. Consul allows you to have it handle the caching, and be notified when a service goes away so it won’t return that address to your application.

xxs 5y ago

the thing can even provide dns... but it has fancy interfaces and an http endpoint. Technically you could do everything with dns just fine. Even if consul provides some sort of liveness (due to latency and concurrency it means little), I can't think of a usable case where the clients won't have retries and ability to maintain multiple open sockets, etc.

fragmede 5y ago
Consul's notion of a service includes port numbers, and while I'm sure you could hack something up using DNS txt records and default port numbers, it's an important distinction because it means multiple instances running on one box can easily be discovered.

nonameiguess 5y ago

I'm not familiar with Consul specifically, but service meshes I am familiar with give you a lot more than just mapping of service names to dynamic IPs. They bundle things like TLS termination, reverse proxying, network policy enforcement, automatic certificate provisioning and key rotation, firewalls potentially aware of anything from layer 3 to layer 7. Where I think companies are going about this wrong sometimes is thinking having their networks be software-defined and handled by some all-in-one product suite means they no longer need network engineers and can they just rely entirely on application developers who specialize in general programming and fall back to vendor support contracts if anything gets too confusing. Admittedly, there's some self interest speaking there, because I work as a consulting engineer for one of these vendors where we go way beyond "support" to embed full time in external product teams with a dependency on our products (though we also offer basic support for companies that think they can get away with it). But to my mind, no software suite can let you get away with not needing any kind of IT ops at all. Smaller companies may assess that the risk is worth it to focus solely on product, but as far as I can tell, Roblox is not a small company (or shouldn't be, given the traffic scale of their platform).