Akka.Discovery

[ismaelhamed]

Akka Discovery provides an interface around various ways of locating services. The built in methods are:

• Configuration
• Aggregate
• DNS

Current known limitation

Endpoints should be defined as a list of configs:

akka.discovery.config.services = {
  service1 = {
    endpoints = [
      {
        host = "cat"
        port = 1233
      },
      {
        host = "dog"
        port = 1234
      }
    ]
  }
}

But AFAIK this is not possible with current Hocon implementation, at least unless #293 is implemented. So, in the mean time I have resorted to define endpoints as a lists of strings (much like we do with seed-nodes):

akka.discovery.config.services = {
  service1 = {
    endpoints = [
        "cat:1233",
        "dog:1234"
    ]
  }
}

[ismaelhamed]

I hope this is fine for new projects.

[Aaronontheweb]

Yep, that should be fine as long as we don't use default interfaces - which aren't binary backwards compatible

[ismaelhamed]

Resolve is recursive. I think its fine, but it's open for improvements.

[Aaronontheweb]

if someone runs into an issue with it, they we can always change it later

[ismaelhamed]

I hope this is fine for new projects.

[ismaelhamed]

Missing GetConfigList, not currently supported

[Aaronontheweb]

@Arkatufus is this something we need to add to the HOCON spec?

[ismaelhamed]

I've linked an issue on the HOCON repo to this

[Aaronontheweb]

@ismaelhamed looks like you're off to a great start! I'll do a deeper review soon - but do we need to wait until the DNS discovery is available before we consider merging this? Just want to know if I should wait for that before diving in.

[ismaelhamed]

Since both Config and Aggregate options are ready, IMO you should merge this as soon as you approve it. There seems to be some work to do on the Akka.Io.Dns in order to implement the DNS API, and that's something that you guys might want to plan carefully.

Also, I understand this new module will be released as a beta package first, so having it half-backed for now shouldn't be a problem.

[Aaronontheweb]

Going to review this today

[Aaronontheweb]

Some minor changes that I documented - but none worth blocking the merge of this PR. I'll send in a separate PR to add the beta tag for Akka.Discovery so we can include this as part of Akka.NET v1.4.12

[Aaronontheweb]

File name is technically wrong here

[Aaronontheweb]

LGTM

[Aaronontheweb]

need to add a tag here to mark this as a pre-release module

[Aaronontheweb]

Should probably have an XML-DOC comment here

[Aaronontheweb]

@ismaelhamed could you open an issue describing the Akka.IO DNS changes that we need to make in order to support DNS-based service discovery? We should start planning for those.

[mchandschuh]

Was DNS discovery ever implemented, and if not, is there an expected timeline and/or an issue available to track the progress (tried searching but didn't find it). Thanks!