A native Scala client for interacting with Consul. There is currently one supported client, which uses http4s to make HTTP calls to Consul. Alternative implementations could be added with relative ease by providing an additional free interpreter for the ConsulOp algebra.

Add the following to your build.sbt:

libraryDependencies += "io.verizon.helm" %% "http4s" % "1.3.+"

The Helm binaries are located on maven central, so no additional resolvers are needed.

Consul operations are specified by the ConsulOp algebra. Two examples are get and set:

import helm._

val s: ConsulOpF[Unit] = : ConsulOp.set("key", "value")

val g: ConsulOpF[Option[String]] = : ConsulOp.get("key")

These are however just descriptions of what operations the program might perform in the future, just creating these operations does not actually execute the operations. In order to perform the gets and sets, we need to use the http4s interpreter.

First we create an interpreter, which requires an http4s client and a base url for consul:

import helm.http4s._
import org.http4s.Uri.uri
import org.http4s.client.blaze.PooledHttp1Client

val client = PooledHttp1Client()
val baseUrl = uri("http://127.0.0.1:8500")

val interpreter = new Http4sConsulClient(baseUrl, client)

Now we can apply commands to our http4s client to get back Tasks which actually interact with consul.

import scalaz.concurrent.Task

val s: Task[Unit] = helm.run(ConsulOp.set("testkey", "testvalue"))(interpreter)

val g: Task[String] = helm.run(ConsulOp.get("testkey"))(interpreter)

// actually execute the calls
s.run
g.run

Typically, the Helm algebra would be a part of a Coproduct with other algebras in a larger program, so running the Task immediately after helm.run is not typical.

Contributions are welcome; particularly to expand the algebra with additional operations that are supported by Consul but not yet supported by Helm.