在生产中运行Lagom

Question

I am working on setting up a Lagom application in production. I have tried contacting Lightbend for ConductR license but haven't heard back in ages. So, now I am looking for an alternative approach. I have multiple questions.

Since the scale of the application is pretty small right now, I think using a static service locator works for me right now (open to other alternatives). Also, I am using MySQL as my event store instead of the default configuration of Cassandra (Reasons not relevant to this thread).

To suppress Cassandra and Lagom's Service Locator, I have added the following lines to my build.sbt:

lagomCassandraEnabled in ThisBuild := false

I have also added the following piece to my application.conf with service1-impl module.

lagom.services {
    service1 = "http://0.0.0.0:8080"
}

For the dev environment, I have been able to successfully run my application using sbt runAll in a tmux session. With this configuration, there is no service locator running on the default 8000 port but I can individually hit service1 on 8080 port. (Not sure if this is the expected behaviour. Comments?)

I ran sbt dist to create a zip file and then unzipped it and ran the executable in there. Interestingly, the zip was created within the service1-impl folder. So, if I have multiple modules (services?), will sbt dist create individual zip files for each of the service?

When I run the executable created via sbt dist , it tries to connect to Cassandra and also launches a service locator and ignores the static service locator configuration that I added. Basically, looks like it ignores the lines I added to build.sbt. Anyone who can explain this?

Lastly, if I were to have 2 services, service1 and service2, and 2 nodes in the cluster with node 1 running service1 and node 2 running both the services, how would my static service locator look like in the application.conf and since each of the service would have its own application.conf, would I have to copy the same configuration wrt static service locator in all the application.confs?

Would it be something like this?

lagom.services {
    service1 = "http://0.0.0.0:8080"
    service1 = "http://1.2.3.4:8080"
    service2 = "http://1.2.3.4:8081"
}

Since each specific actor would be spawned on one of the nodes, how would it work with this service locator configuration?

Also, I don't want to run this in a tmux session in production. What would be the best way to finally run this code in production?

Answer 1

You can get started with ConductR in dev mode immediately, for free, without contacting sales. Instructions are at: https://www.lightbend.com/product/conductr/developer You do need to register (read: provide a valid email) and accept TnC to access that page. The sandbox is free to use for dev mode today so you can see if ConductR is right for you quickly and easily.

For production, I'm thrilled to say that soon you'll be able to deploy up to 3 nodes in production if you register w/Lightbend.com (same as above) and generate a 'free tier' license key.

Lagom is opinionated about microservices. There's always Akka and Play if those opinions aren't shared by a project. Part of that opinion is that deployment should be easy. Good tools feel 'right' in the hand. You are of course free to deploy the app as you like, but be prepared to produce more polyfill the further from the marked trails you go.

Regarding service lookup, ConductR provides redirection for HTTP service lookups for use with 'withFollowRedirects' on Play WS [1] Regarding sbt dist , each sub-project service will be a package. You can see this in the Chirper example [2] on which sbt dist generates chirp-impl.zip, friend-impl.zip, activity-stream-impl, etc as seen in the Chirper top level build.sbt file. As that ConductR is the clean and lighted path, you can reference how it does things in order to better understand how to replace Lagom's deployment poly w/ your own. That's the interface Lagom knows best. Much of ConductR except the core is already OSS so can try github if the docs don't cover something.

Disclosure: I am a ConductR-ing Lightbender.

1. http://conductr.lightbend.com/docs/1.1.x/ResolvingServices

2. git@github.com:lagom/activator-lagom-java-chirper.git